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## Meet the editors

Dr. Rao is a Professor Emeritus in the Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Ontario, Canada. He is an expert in diet and health and his research has focused on the role of oxidative stress and antioxidant phytochemicals in the causation and prevention of chronic diseases, with emphasis on the role of carotenoids and polyphenols. His research interests also include the role of prebiotics and pro-

biotics in human health. He has 100 publications in scientific journals and several books and book chapters to his credit. Dr. Rao has had a distinguished academic career spanning more than 45 years. He is popularly sought after by the international media for his opinions about nutrition and health.

Dr. Leticia Rao is a Professor Emeritus at the University of Toronto, Ontario, Canada, and former director of the Calcium Research Laboratory at the same university. She is also a former staff scientist at St. Michael's Hospital, Toronto, Ontario. Her expertise is in bone cell biology with a focus on preventing osteoporosis. She studies bone cells in the laboratory and carries out basic and clinical studies of drugs, nutritional supplements, and

phytonutrients including carotenoids and polyphenols in postmenopausal women. Her research has been presented at national and international conferences and symposia and she has published extensively in peer-reviewed scientific journals. She has co-authored one book and edited eight others on nutrition and health. Dr. Rao has frequently presented her work at international organisations.

### Contents


Preface

Dietary supplements, also referred to as phytonutrients, nutraceuticals, and functional ingredients, contain not only essential vitamins and minerals but also beneficial compounds present in the diet. Recently, there has been a great deal of interest from consumers, health professionals, and regulatory agencies in the use, benefits, safety, and regulatory guidelines of dietary supplements. Unlike vitamins and minerals, phytonutrients do not have recommended levels of daily intake; rather, consumers are advised to consume foods that are good sources of these phytonutrients as part of a healthy diet. Manufacturers of health supplements have taken advantage of the surging interest in these products, claiming that they play an important role in the management of health. The overall interest in supplements has also prompted health professionals to undertake extensive research and develop guidelines for their consumption and safety. Regulatory agencies are also working to make sure that

In recognition of the new information on the composition of dietary supplements, the health issues they are claimed to be beneficial for, their mechanisms of action, and safe levels of consumption, *Dietary Supplements - Challenges and Future Research* provides readers with information to better understand the positive and negative outcomes of consuming supplements. This book contains chapters written by international researchers that address some important aspects of dietary supplements. It is organized into

Section 1, "An Overview of the Role of Dietary Supplements in Human Health," includes one chapter. Chapter 1 by Rao and Rao called " Introductory Chapter: Dietary Supplements, Definitions, Role in Human Health and Regulatory Issues" is an introduction to the need for and the role of dietary supplements in the management of health and prevention of diseases. It defines dietary supplements, presents recent research findings, and discusses regulatory guideline issues. It concludes by identifying the challenges facing these products and the need for further research

for a better understanding of the role supplements play in human health.

Section 2 "Dietary Supplements in Health Management" includes three chapters. Chapter 2, "Supplements and Down Syndrome" by Maja Ergović Ravančić and Valentina Obradović, Chapter 3 "Impact of Glycine Supplementation to Dietary Crude Protein Reduction in Broiler Chickens," by Paschal Chukwudi Aguihe et al., and Chapter 4, "DHA (Docosahexaenoic Acid): A Biomolecule with Diverse Roles and Health Benefits" by Abdul Hei and Laishram Sanahanbi. Together, these three chapters address the role of dietary supplements in disease and health management

Section 3 "Dietary Sources" includes one chapter. Chapter 5, "The Role of Micronutrients and Micronutrient Supplements in Vegetarian and Vegan Diets" by Elizabeth Eveleigh,

supplements are safe and meet manufacturers' health claims.

three sections.

using human and animal studies.

## Preface

Dietary supplements, also referred to as phytonutrients, nutraceuticals, and functional ingredients, contain not only essential vitamins and minerals but also beneficial compounds present in the diet. Recently, there has been a great deal of interest from consumers, health professionals, and regulatory agencies in the use, benefits, safety, and regulatory guidelines of dietary supplements. Unlike vitamins and minerals, phytonutrients do not have recommended levels of daily intake; rather, consumers are advised to consume foods that are good sources of these phytonutrients as part of a healthy diet. Manufacturers of health supplements have taken advantage of the surging interest in these products, claiming that they play an important role in the management of health. The overall interest in supplements has also prompted health professionals to undertake extensive research and develop guidelines for their consumption and safety. Regulatory agencies are also working to make sure that supplements are safe and meet manufacturers' health claims.

In recognition of the new information on the composition of dietary supplements, the health issues they are claimed to be beneficial for, their mechanisms of action, and safe levels of consumption, *Dietary Supplements - Challenges and Future Research* provides readers with information to better understand the positive and negative outcomes of consuming supplements. This book contains chapters written by international researchers that address some important aspects of dietary supplements. It is organized into three sections.

Section 1, "An Overview of the Role of Dietary Supplements in Human Health," includes one chapter. Chapter 1 by Rao and Rao called " Introductory Chapter: Dietary Supplements, Definitions, Role in Human Health and Regulatory Issues" is an introduction to the need for and the role of dietary supplements in the management of health and prevention of diseases. It defines dietary supplements, presents recent research findings, and discusses regulatory guideline issues. It concludes by identifying the challenges facing these products and the need for further research for a better understanding of the role supplements play in human health.

Section 2 "Dietary Supplements in Health Management" includes three chapters. Chapter 2, "Supplements and Down Syndrome" by Maja Ergović Ravančić and Valentina Obradović, Chapter 3 "Impact of Glycine Supplementation to Dietary Crude Protein Reduction in Broiler Chickens," by Paschal Chukwudi Aguihe et al., and Chapter 4, "DHA (Docosahexaenoic Acid): A Biomolecule with Diverse Roles and Health Benefits" by Abdul Hei and Laishram Sanahanbi. Together, these three chapters address the role of dietary supplements in disease and health management using human and animal studies.

Section 3 "Dietary Sources" includes one chapter. Chapter 5, "The Role of Micronutrients and Micronutrient Supplements in Vegetarian and Vegan Diets" by Elizabeth Eveleigh,

Lisa Coneyworth and Simon Welham presents information on the presence of micronutrients in vegetarian and vegan diets and discusses the significance of these diets in meeting the recommended levels of nutrients.

Overall, this book provides important information to consumers, health professionals, researchers, and regulatory agencies that are helpful for understanding various aspects of dietary supplements as well as the challenges faced in human health. It also provides a guide to future research in the field.

#### **A. Venketeshwer Rao**

Professor Emeritus, Faculty of Medicine, Department of Nutritional Sciences, University of Toronto, Ontario, Canada

> **Leticia Rao** Professor Emeritus, University of Toronto, Toronto, Canada

> > **1**

Section 1

An Overview of the Role

of Dietary Supplements

in Human Health

Section 1

## An Overview of the Role of Dietary Supplements in Human Health

### **Chapter 1**

## Introductory Chapter: Dietary Supplements, Definitions, Role in Human Health and Regulatory Issues

*A. Venketeshwer Rao and Leticia Rao*

### **1. Introduction**

National dietary guidelines are the ideal way to meet all the nutritional requirements for a healthy life. However for genetic, health or lifestyle-related activities, not everyone can follow these dietary guidelines. Not following the dietary guidelines can result in individuals not being able to meet their nutritional requirements leading to health-related issues. In the belief that they may not be meeting the required levels of nutrients, either justified or not, they take 'supplements' as insurance towards nutrient adequacy and good health. A common understanding of dietary supplements is presented in **Table 1**. **Figure 1** shows a typical dietary supplement fact of a commercial product [1]. Traditionally, the focus of dietary supplements is essential vitamins and minerals. However, in recent years, other biologically active components of foods have also been identified as playing an important role in human health [2, 3]. Although technically they are not 'nutrients', they are referred to as 'phytonutrients', 'nutraceuticals', functional ingredients' and 'bioactive beneficial compounds. They include compounds such as carotenoids, polyphenols, dietary fibre and many more from plant and animal kingdoms. Nutritionists and other health professionals now believe that consuming these phytonutrients as part of a


<sup>•</sup> A dietary supplement is a product that is manufactured with the aim of supplementing one's regular diet. They are not intended to treat, diagnose, prevent or cure diseases*.*


#### **Figure 1.**

*Typical dietary supplement facts of a commercial product [1].*

daily diet is beneficial to maintain good health and avoiding diseases. However, being a new area of research, in most cases, there are no recommended levels of their intake except to advise consumers to include foods that are good sources of these phytonutrients as part of their healthy diet. This concept of taking supplements has gained popularity in recent years. Recognising the potential for a business opportunity, business sectors around the globe are now offering a wide range of dietary and nutritional supplements. This increase in the intake and sales of supplements has raised serious concerns among health professionals and government regulatory agencies. Questions are now being raised regarding the validity of the scientific evidence in support of supplements and possible misuse leading to adverse effects. In view of the importance of the issue of dietary supplements, several review articles have been published over the years [4–8], and it was felt that there was a need for a book on this topic to provide current knowledge on the research that is being conducted and provide science-based opinions relating to the use of supplements.

#### **2. Challenges and future research**

Undoubtedly, nutrient deficiencies such as vitamin A, iron, folic acid and vitamin D, to name a few, have been documented to affect the health of infants, children and childbearing women in the developing parts of the world. However, they are not restricted only to developing countries but also to industrialised countries. The reasons could include genetic factors, insufficient access to proper food, insufficient knowledge of nutrient requirements and their sources, and lifestyle factors. Dietary supplements, therefore, have a rightful place in providing the needed nutrients and other beneficial bioactive compounds to at-risk needy consumers. As a result, sales of these supplements have increased globally, indicating the awareness of the need for these compounds to maintain good health. However, there are still many challenges that the scientific community, consumers, manufacturers and regulatory agencies face in ensuring that the supplements being marketed and consumed are safe and indeed provide the healthy benefits claimed on the label [5].

As more and more new information is available relating to dietary supplements, one of the first challenges facing consumers and regulatory agencies is to define and understand what a dietary supplement is and differentiate them from medicines. Two important aspects of being considered are the intended use of the product and the claim(s) the product is associated with [6, 8]. In countries like the USA, Canada and

#### *Introductory Chapter: Dietary Supplements, Definitions, Role in Human Health and Regulatory… DOI: http://dx.doi.org/10.5772/intechopen.110644*

Australia, dietary supplements are considered as being self-selecting with limited claims in support of overall health and wellness and not requiring a prescription from a medical practitioner [5]. However, these guidelines are not always universally applied and vary from country to country. As mentioned in their article by Dwyer et al. [5], melatonin is regulated in the USA as a dietary supplement, in Canada as a Natural Health Product (NHP), and in Australia as a prescription medicine. As more and more marketing of dietary supplements is becoming a global issue, a clear and well-defined definition is essential to minimise confusion.

Another challenge is to have good science-based evidence in support of the claims that are often associated with dietary supplements. The two considerations that are important relate to the compound itself that is being evaluated and the design of the study being used. With respect to the compound itself, its source, purity and scientifically valid analytical procedures for its evaluation are important. With regard to the study design, if is absolutely essential that it is in accordance with scientifically accepted procedures of being double-blind with appropriate controls. If it is a clinical trial, the nature of the subjects participating, their health status, gender and age, length of administration of the compound being administered, procedures used to evaluate end results, and statistical procedures used in arriving at the results. In other words, the results derived from the study followed all the scientifically accepted procedures.

In addition to the challenges mentioned above, one of the most important challenges is faced by the regulatory agencies [5]. Unfortunately, no one regulatory model is used globally based on their regional priorities and needs. However, one common consideration of the different regulatory models used globally is to assure the consumers that the dietary supplements are safe and meet the claims made by the manufacturers. We have come a long way in developing a regulatory framework to achieve the goals of safety and applicability. However, as more and more new compounds are now being identified as beneficial for good health and marketing, much more work needs to be done in the future.

This introductory chapter aims to provide readers with a better understanding of the need for dietary supplements, what they are and the challenges faced by the industry, consumers, scientists and regulatory agencies. The common goal of all these stakeholders is safety and good health.

#### **Author details**

A. Venketeshwer Rao\* and Leticia Rao University of Toronto, Toronto, Ontario, Canada

\*Address all correspondence to: venket.rao18@gmail.com

© 2023 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

#### **References**

[1] Available from: https://www. mouseprint.org/2014/09/01/someonline-stores-make-shoppers-buyvitamins-blindly/

[2] Rao V. Phytochemicals. A Global Perspective of their Role in Nutrition and Health. London, UK: IntechOpen; 2012

[3] Rao AV, Manns D, Rao L, editors. Phytochemical in Human Health. London, UK: IntechOpen; 2020

[4] Abubakar AA et al. A review on dietary supplements: Health benefits, market trends, and challenges. 2020. International Journal of Scientific Development and Research. 2020;**5**:26-34

[5] Dwyer JT, Coates PM, Smith MJ. Dietary supplements: Regulatory challenges and research resources. Nutrients. 2018;**10**:41-64

[6] Coates PM, Betz JM, Blackman MR, Crogg GM, Levine M, Moss J, et al., editors. Encyclopedia of Nutritional Supplements. 2nd ed. Boca Raton: CRC Press; 2010

[7] Journal of Dietary supplements. Taylor and Francis. Available from: https://www.tandforline.com/journals/ ijds20

[8] US Food & Drug Administration. What's New in Dietary Supplements. Washington DC: US Food & Drug Administration; 2022

Section 2

## Dietary Supplements in Health Management

#### **Chapter 2**

## Supplements and Down Syndrome

*Maja Ergović Ravančić and Valentina Obradović*

#### **Abstract**

Down syndrome (DS) is one of the most common genetic disorders associated with a number of difficulties that are visible through the motor and cognitive development. Some theories claim that intake of supplements in very high doses could upgrade the physical and intellectual status of individuals with DS. Numerous papers have been published to support these theories, but at the same time, a great number of papers have warned of the risks of uncontrolled, excessive use of dietary supplements and asked for the proof of such claims by independent scientific studies. In this chapter, we will provide a review of the most commonly used supplements and major findings on this matter. Open access to information about the positive and negative sides of such supplementation is primarily important for guardians of people with DS in order to make the decision whether to use such preparations. It could also be an incentive for scientists to focus on the development of beneficial and safe therapies.

**Keywords:** Down syndrome, trisomy 21, oxidative stress, supplements, genes

#### **1. Introduction**

The aim of this chapter is to provide the reader with scientifically based information about the possibilities and dangers of using nutritional supplements for individuals with Down syndrome (DS). DS or trisomy 21, first described by Dr. John Langdon Down in 1866, is one of the most common genetic disorders that impact fetal development. It is a chromosomal disorder where an individual has an additional copy of chromosome 21, which may be full or partial [1]. The prevalence of children with DS worldwide is between 1:319 and 1:1000, and depends on the age of the mother (1/2000 in teenage girls to 1/40 in 42-year-old women) sociocultural, religious variables, and the possibility of terminating a pregnancy [2–4]. Every child with DS has unique phenotypic characteristics on which their overall physical and cognitive development depends, so the medical conditions associated with DS are not the same for every child (**Figure 1**). Considering the high cure rate of various comorbidities from which a DS child can suffer before and after birth, the mortality rate fell from 14.2% to 2.3% [5]. The life expectancy of people with DS has increased significantly over the last century, up to 60 years [6]. The use of nutritional supplements for children with DS is a topic that is extremely important for parents and caregivers as they want to improve their child's cognitive functions and health. However, the danger to the child can arise when the use of dietary supplements is uncontrolled, in large doses, and without a prior nutritional status of the organism. The program of early intervention with dietary supplements has been increasingly mentioned in connection with DS,

**Figure 1.** *A three-year-old child with Down syndrome. (source: author).*

however, research on the benefits of their use is still very unsupported by concrete evidence that would give doctors guidance for their recommendation.

### **2. Down syndrome**

Since the discovery that DS is a result of trisomy 21, the main interest of the studies has been the identification of human chromosome 21 genes (Hsa21), and the impact of their overexpression on the DS phenotype [7]. To explain the similarities and differences in the phenotypic characteristics associated with DS, a gene dose imbalance theory has been hypothesized stating that patients with DS have an increased dose or number of gene copies on Hsa21, which may lead to increased gene expression. This includes the possibility that specific genes or subsets of genes can control specific phenotypes of DS, but also that a nonspecific dose of a number of trisomic genes leads to a genetic imbalance that has a major impact on the expression and regulation of many other genes throughout the genome. Phenotypic analyzes found that only one or a few small chromosomal regions, termed "critical regions of Down syndrome," (DSCR) a region of 3.8–6.5 Mb at 21q21.22, with approximately 30 genes are responsible for most DS phenotypes [8, 9]. There are numerous physical features and congenital conditions specific to DS, resulting from overexpression of genes caused by the extra chromosome presented in **Table 1**. Every child is unique and features and conditions are not equally expressed and represented.

#### *Supplements and Down Syndrome DOI: http://dx.doi.org/10.5772/intechopen.106655*


#### **Table 1.**

*Possible physical features and congenital conditions associated with Down syndrome [9].*

Promoting the health of people with DS is extremely important because it creates a prerequisite for improving their quality of life. Dietary composition, macronutrient and micronutrient intake, eating habits, and lifestyle can be fundamental for maintaining good health. Proper nutrition can have a major impact on preventing or delaying the onset of certain diseases in people with DS. However, very often nutrients from food are not enough to fulfill the daily needs for basic nutrients due to difficulties with swallowing and chewing, excessive sensory sensitivity, and numerous health problems, such as celiac disease. Cardiopathy in infants can impair food tolerance and adverse conditions may increase the frequency of aspiration [10].

In order to compensate for the lack of key nutrients necessary for the proper functioning of the body and fill the gap between diet and health in children with DS, dietary supplements can be used, but their usage should be controlled and in accordance with the identified deficiencies in the body.

#### **3. History of nutritional supplementation for DS**

Based on the assumption that an extra chromosome causes a metabolic imbalance that can be affected by various dietary supplements, Dr. Henry Turkel developed

the first formulation composed of 48 different substances called "U-series" in the 1940s. The Food and Drug Administration (FDA) rejected his request for a new drug because it could not serve as a cure. A modified supplement formula was developed by Dr. Jack Warner during the 1980s as high-performance capsules (HAP Caps), which contained high doses of dietary antioxidants, such as vitamins A, E, and C, digestive enzymes, minerals zinc (Zn), copper (Cu), manganese (Mn), and selenium (Se), in order to correct metabolic disorders. HAP caps were formulated in the FDA laboratory and had approval from 1986 until his death in 2004 [11, 12]. During this period, Dixie Lawrence Tafoya, combining elements of both treatments with the addition of new ingredients, developed a combination of targeted nutritional intervention (TNI) supplements that included amino acids and smart drugs (Piracetam) in addition to various micronutrients. These supplements were promoted under the name Nutrivene. In Canada, under the leadership of Kent Macleod, Nutrichem Laboratories has launched a supplement called "MSB Plus" in accordance with the standards of good manufacturing practice at the licensed Health Canada Site. Despite the fact that various supplements have been applied to children with DS since the 1950s, repeated studies have shown that there are no nutritional deficiencies that would apply to all children with DS. Furthermore, there is no objective study that has confirmed the need for any of these supplements, with the possible exception of the minerals Zn and Se [12, 13].

Sacks & Buckley [12] pointed out the lack of well-designed scientific studies and warned of the danger of overdose in the case of supplement introduction in addition to a balanced diet. Many studies that support supplementation involved a small number of subjects, a wide range of age participants, short duration, and very few randomized controlled and blind studies [14, 15].

The popularity of supplements was confirmed by a survey among 1,200 respondents in the US, Brazil, and the EU that found that almost half of pediatric patients with DS have used or are currently using dietary supplements. 20% of surveyed parents who gave their child supplements haven't informed the pediatrician about it. Above all, supplements given to children with DS often exceeded the recommended daily doses [16]. Nevertheless, dietary supplements for DS still receive a lot of attention from parents, which leads to efforts of scientists to define the possible benefits of dietary supplements for people with DS-based on scientifically based knowledge.

#### **4. DS issues targeted by nutritional supplementation**

#### **4.1 Oxidative stress**

The theory of oxidative stress involves the occurrence of oxygen radicals, called reactive oxygen species (ROS) during oxidative metabolism. ROS include superoxides (O2 •<sup>−</sup>) and hydroxyl (OH •) free radicals and other molecules, such as hydrogen peroxide (H2O2) and peroxynitrite which have the ability to become very harmful to cells. To defend against ROS, cells developed various mechanisms to eliminate them: antioxidant enzymes (superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT)) along with antioxidants, such as vitamins C, E, or glutathione. If an imbalance between oxidants and antioxidants happens in cells, oxidative stress occurs [17, 18]. Numerous studies point to oxidative stress as a possible explanation for a number of DS-related problems, such as intellectual disability, accelerated aging, and cognitive and neuronal dysfunction [14, 19–21].

*Supplements and Down Syndrome DOI: http://dx.doi.org/10.5772/intechopen.106655*

**Figure 2.** *Oxidative stress in Down syndrome.*

The 21st chromosome contains SOD1 gene, which encodes the enzyme Cu-Zn superoxide dismutase (Cu-Zn SOD), responsible for the conversion of O2 <sup>−</sup> to H2O2 in the cytosol. Increased SOD1 activity results in the creation of elevated levels of H2O2 that should be effectively removed by other enzymes, such as CAT, GPx, and thioredoxin peroxidase. Excess of chromosomes leads to overexpression of the SOD1 gene, and to elevated H2O2 levels that cannot be completely eliminated by CAT and GPx, so overproduction of ROS occurs (**Figure 2**) [22–25]. SOD1 was found to be 50% higher than normal in various cells and tissues of people with DS, so the SOD1/GPx activity ratio was consequently altered [19, 22, 26–29].

Strydom et al. [30] in his study on 32 adults with DS could not confirm the hypothesis that an increased SOD1/GPx ratio leads to low cognitive results. Surprisingly, they found that a low SOD1/GPx ratio leads to bad memory ability. They also pointed out that other possible factors could also affect SOD1 and GPx activity, such as regular exercise, Se, and homocysteine levels.

#### **4.2 Cognitive development**

Research has shown that the maturation of certain areas of the brain during childhood is associated with the development of specific cognitive functions, such as language, reading, and memory [31, 32]. Rapid brain growth occurs during the first 2 years of life (at age 2, the brain reaches 80% of an adult's weight), so this period of life may be particularly sensitive to nutritional deficiencies [33].

Nutrition, as the link between nutrients and health, should provide the building blocks needed to build and maintain the structure and function of the central nervous system. The intellectual disorder occurs when a child fails to fully develop the intellectual ability to think, reason, learn and understand. Children with intellectual disabilities also have problems in learning adaptive behavior, which encompasses the social and practical skills needed for everyday life. Intellectual impairment varies among children with Down syndrome. It ranges from a severe intellectual impairment that makes people completely dependent on caregivers, to mild effects that allow people to think and learn at levels that allow them to continue their higher education, keep their jobs, and live independently.

It is thought that nutrition may play a key role in brain development, and, thus intellectual functioning. The brain, similar to the rest of the body, needs proteins, fats, carbohydrates, vitamins, and minerals to grow and function, which are ingested through food or supplementation if food intake is difficult. As the brain develops faster than the rest of the body, it is obvious to consider that a lack of nutrition at

a critical stage of development can lead to permanent changes in the structure and functioning of the brain. In addition, the brain is the most metabolically active organ in the body, but it has very limited energy reserves, so it relies on a diet for a continuous supply of glucose. Similarly, minute-by-minute brain function requires an adequate supply of micronutrients that act as coenzymes or form structural parts of enzymes required for optimal metabolic activity [34, 35].

#### **4.3 Neurodegenerative diseases**

Since individuals with DS are prone to elevated levels of oxidative stress at an early age and consequent accumulation of ROS, which are cytotoxic byproducts of normal mitochondrial metabolism, there is an insufficient defense of endogenous antioxidants. In this case, oxidative molecules can disrupt cellular functions by affecting synaptic plasticity, ultimately leading to neuronal injury and apoptosis. Individuals with DS over the age of 35 have a higher frequency of short-term memory impairment and an increase in the rate of dementia, aphasia, and agnosia, while executive function impairments are evident as early as adolescence. One of the most important genes associated with DS is amyloid precursor protein (APP), a gene encoded on chromosome 21. Increased APP production may contribute in part to oxidative stress associated with neurodegenerative diseases and inflammation. Accumulation of amyloid-beta monomers can directly disrupt mitochondrial function resulting in reduced energy and accumulation of amyloid plaques leading to activation of inflammatory cascades [36, 37].

Alzheimer disease (AD) is a form of dementia that can most commonly develop in people with DS, as in the general population. Unfortunately, effective drugs have not yet been developed to be available to treat dementia in DS. Prevention is crucial to alleviate the symptoms of neurodegenerative diseases, but also to delay them. Detection of biomarkers and the development of sensitive cognitive screening tools will be essential for earlier diagnosis and better therapeutic management [38]. There are numerous studies on how to reduce or slow down the course of neurodegenerative diseases, such as AD, in people with DS. The causes of AD in people with DS is associated with overexpression of genes and lack of nutrients due to poor diet can be influenced by regulation of endogenous antioxidants, intake of vitamins, minerals, polyunsaturated fatty acids, and polyphenols [39–42].

#### **5. Commonly used nutritional supplements for individuals with Down syndrome**

#### **5.1 Vitamins**

As explained in the previous chapter, increased oxidative stress in individuals with DS is present from early life, leading to lipid peroxidation and DNA damage [43]. For that reason, antioxidant vitamins have been the focus of many research (**Table 2**). Vitamin E, especially its form known as α-tocopherol, is a strong antioxidant, important for the prevention of oxidation of unsaturated fatty acids in cell membranes [49, 50]. Some studies involved trisomy 16 mouse models in order to get a basis before clinical trials on DS humans because these mice have increased oxidative stress and cerebral pathology similar to DS [51–54].

#### *Supplements and Down Syndrome DOI: http://dx.doi.org/10.5772/intechopen.106655*


#### **Table 2.**

*Examples of vitamin supplementation research for DS individuals.*

Lockrow et al. [43] suggested that transgenic mice could be used in order to get insight into the molecular pathways of the disease and to test the efficiency of drugs. They also warned that mice do not manifest all the features as humans do. Still, they proved a correlation between high oxidative stress in transgenic mice and low working memory. The introduction of vitamin E to the diet of mice gave positive results on oxidative stress and neuronal markers. They also suggested that this could be a good starting point for the treatment of neurodegenerative diseases, such as DS and AD, in humans. Lott [55] pointed out that clinical studies on humans still did not provide satisfactory results, although animal studies in oxidative stress are promising.

As presented in **Table 2**, studies on humans had very different experimental groups in the number of participants, age, and dosage of supplements. The conclusions they

obtained were also very different. Lockrow et al. [43] and Lott [55] suggested that vitamin E supplementation could exhibit better results if implemented at younger age as preventive therapy for dementia, but it requires additional clinical trials. Tanabe et al. [56] could not find a correlation between elevated Cu-Zn SOD activity and cellular vitamin E status in DS.

It can be seen that a combination of vitamins E and C have been commonly used. Vitamin C helps to maintain a stable concentration of vitamin E in plasma by protecting it from damaging oxidation and keeping it in the active state [49, 57, 58]. The link between cognitive decline in AD and vitamin C intake has been studied by Harrison [18]. He included many studies involving vitamin C or a combination of vitamin C and E in his review article. Contradictory results regarding the usefulness of high doses of vitamin C for the cognitive decline have been provided, but a high connection between the low consummation rate of fruits and vegetables and bad cognitive function has been undoubtfully proved. So, prevention of deficiency by quality nutrition should be the first line of defense against cognitive decline instead of supplementation.

It is very important to remember that high doses of supplements can lead to organ damage, harmful interactions, and toxicity [59]. Besides, reactive oxygen species are necessary for obtaining normal cell functioning, so implementation of high doses of antioxidant supplementation would remove too much ROS disrupting cell signaling pathways [60, 61]. The dietary institute for medicine recommends 22 IU RDA for vitamin E and 75 to 90 mg for vitamin C, which is much lower than the doses usually present in supplements (up to 1000 IU of vitamin E and up to 1000 mg of vitamin C) or which have been used in previously mentioned studies [62].

The deficiency of B12 vitamin is mainly associated with a vegetarian and vegan diet, since it mainly originates from animal products. B12 deficiency in infants can lead to various clinical symptoms, such as hypotonic muscles, involuntary muscle movements, apathy, cerebral atrophy, and demyelination of nerve cells [63, 64]. It has an important role in brain function and development through methylation reactions in the central nervous system. Vitamin B12 is also a cofactor in numerous catalytic reactions in the human body, which are required for neurotransmitter synthesis and functioning. Vitamin B12 deficiency can also result in neuropathy through degeneration of nerve fibers and irreversible brain damage [65]. Folates are also B group, water-soluble vitamins, which serve as coenzymes in a variety of reactions. Numerous enzymes involved in folate transport and metabolism are encoded by genes located on chromosome 21 and represent a potential mechanistic basis for folate dysregulation in children with DS. Potential genetic causes of metabolic folate dysregulation in children with DS, non-genetic factors, such as diet, gender, and age, must be considered because they must fully satisfy their folate needs through their diet since they lack the enzymatic machinery necessary to synthesize their own. There are two possible mechanisms for the influence of folate and vitamin B12 deficiency on the brain: by disrupting myelination or influencing the inflammatory process [66, 67].

Individuals with DS have higher plasma homocysteine concentration than healthy people. There are several possible reasons for changes in its metabolism. The deficiency of vitamin B6, B12, and folic acid is one of the theories explaining the accumulation of homocysteine because those vitamins are important cofactors for its metabolism. High plasma concentration is a result of a high cytotoxic intracellular homocysteine. It is assumed that this is a repercussion of gene overexpression on chromosome 21 [68, 69]. Studies [14, 70–73] proved that intake of high doses of B group vitamins reduced homocysteine levels and reduced the rate of brain atrophy in

#### *Supplements and Down Syndrome DOI: http://dx.doi.org/10.5772/intechopen.106655*

individuals with mild cognitive deterioration. On the other hand, Fillon-Emery et al. [48] presented results, which showed that the plasma homocysteine concentration of individuals with DS who did not take supplemental vitamins was not significantly different from that of controls. Moretti et al. [74, 75] also warned that research on vitamin B supplementation gives contradictory results without scientific evidence for cognitive improvement.

#### **5.2 ω-3 fatty acids**

There are numerous roles of dietary lipids essential for the proper function of cells. They are building material for cellular membranes and bioactive molecules, serve as a source of energy, take part in cell signaling pathways and participate in the regulation of gene expression. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are essential polyunsaturated fatty acids with an omega-3 desaturation that cannot be synthesized in the human body [76].

In total, 60% of the dry weight of the human brain are lipids, of which 20% are DHA and arachidonic acid (AA; an omega-6 fatty acid) the two core fatty acids found in gray matter. For that reason, there is a high interest in the influence of unsaturated fatty acids, especially essential ones, for cognitive brain development [77].

Adequate intake of omega-3-fatty acids is crucial for the normal functioning of brain tissue. As already mentioned, as parts of cell membranes, they influence membrane fluidity and modulate ion channels. They are also important in inflammation and immune reactions, as well as for signal processing and neural transmission [77–79].

#### **5.3 Minerals**

Due to the fact that SOD and GPx, important enzymes involved in oxidative homeostasis of the cells, contain Se and Zn, these minerals are considered as crucial antioxidant vitamins [80, 81]. Some of the studies about the influence of mentioned minerals on DS individuals are presented in **Table 3**. Besides its role in antioxidative enzymes and metabolism, Se influences serum concentrations of IgG2 and IgG4 in children with DS. DS children are very sensitive to respiratory bacterial infections, and it has been proved that Se concentration decreases after severe bacterial infection. In that light, intake of Se could be beneficial for children with DS as a part of the immune response to bacterial antigens [89]. Se is also important for the production of thyroid hormones. The thyroid gland tissue contains a high concentration of Se [90]. In the case of Se deficiency, H2O2 gets accumulated and oxidative stress increases that lead to cell apoptosis [91]. Adequate Se intake is necessary for proper intracellular GPx functioning and protection of thyrocytes from peroxides [26]. Hypothyroidism is common in people with DS, so Se supplementation could be useful in that case [92]. The same as already mentioned for vitamins, adequate intake of Se by proper diet should be considered first. The bioavailability of Se originating from proteinaceous food (meat, fish, shellfish, eggs, and cereals) varies from 20% to 80% (the best is from cereals and yeast). It is mainly in the form of selenomethionine. In supplements, the inorganic form of Se, sodium selenite, is mainly used and has excellent bioavailability [91, 93, 94].

Zinc deficiency slows growth because it is involved in the activity of more than 200 enzymes, especially those associated with the synthesis of RNA and DNA. It is important for the function of numerous enzymes and transcription factors [95].

Experimental and clinical studies have found that zinc metabolism is altered in individuals with Down syndrome (**Table 3**). Lima et al. [85], reported that adequate


#### **Table 3.**

*Examples of research on mineral status in DS individuals.*

#### *Supplements and Down Syndrome DOI: http://dx.doi.org/10.5772/intechopen.106655*

zinc intake was observed in 40% of children with DS and in 67% of the control group and zinc concentrations were significantly lower in plasma and urine and higher in erythrocytes of children with DS. There are several possible reasons for that: low plasma Zn concentration could be a result of a redistribution of a mineral in an organism, and not an inhibition of its absorption. A high level of erythrocytes Zn may be a consequence of increased Cu-Zn SOD activity. If DS children are iron deficient (which occurs quite often), Zn binds to the protoporphyrin instead of the iron [85]. Many symptoms of children and adults with DS are a consequence of excessive synthesis of multiple gene products, including an increase in the intracellular activity of Cu-Zn SOD due to overexpression of genes present on chromosome 21. Zinc stabilizes the 3D structure of SOD, and, thus reduces the imbalance [85]. It also participates in the formation of thyroid hormones, leucocytes, and antibodies [49, 96, 97].

#### **5.4 Polyphenols**

Mitochondria are the primary site for the creation of free radicals due to the production of adenosine triphosphate (ATP) through oxidative phosphorylation (OXPHOS), so elevated oxidative stress in individuals with DS primarily affects these organelles. DS individuals have decreased efficiency in producing ATP and reduced respiratory capacity. Mitochondria dysfunction primarily influence brain functioning because of its high susceptibility to energy deficit [98].

Epigallocatechin gallate (EGCG) originating from green tea has been studied in mouse and cell models, and it has been found that it is effective as a ROS scavenging agent, mitochondrial apoptosis protector, mitochondrial bioenergetics activator, and respiratory chain promotor [98, 99]. On the other hand, *in vivo* tests found that EGCG bioavailability is low, due to poor absorption and metabolic modification. It is still unknown whether metabolites reach the brain and influence cell metabolism [99]. Torre and Dierssen [75] warned that many clinical trials in DS patients have limitations, such as poor design, a reduced number of participants, a lack of methods for the neuropsychological evaluation of patients, and the dependence on the IQ of individuals.

It is considered that concentrations of polyphenols normally present in foods are too low to exhibit a beneficial effect on metabolic pathways, so supplementation should be implemented in the daily routine of individuals with DS [100]. This opens an important question about the dosage. Namely, EGCG in high doses acts as a prooxidant with harmful effects on skeletal DS phenotypes, liver, kidney, thymus, spleen, and pancreas [101, 102]. 10 mg/kg/day of EGCG has been found as safe, and effective on mitochondrial and behavioral dysfunction by a case study on a 10-year-old DS child. Although studies on mouse models targeted doses of 10/mg/kg/day–50 mg/kg/day as harmful without positive effect [100]. Long et al. [102] in his survey found that commercially available preparations ranged from 351 mg/day to 2000 mg/day. Some respondents included in this survey reported improvement in speech, memory, learning, and energy, while the others quit supplementation due to the lack of improvements.

Research provided by Xicota et al. [103] tried to determine the influence of EGCG supplementation (9 mg/kg) on body weight. It is considered that EGCG decreases the absorption of lipids and glucose. The survey followed the DS group during 12 months of supplementation and additional 6 months after quitting the treatment. Male subjects exhibited less body weight gain, unlike female subjects, but the authors did not provide an explanation for such results and further research should be done in order to confirm these findings.

Resveratrol originating from different berries, grapes, red wine, and peanuts is another polyphenol used as a therapy for the improvement of mitochondrial functions and diminishing some of the DS clinical features [100]. The same as already mentioned for EGCG, bioavailability is low and its original form quickly changes into metabolites [104]. Studies on the experimental rats determined doses of 700 mg/ kg/day as safe [104]. Considering the fact that it is not the resveratrol that reaches targeted tissues but its metabolites, those molecules should be the focus of research in future as a treatment for DS.

#### **5.5 Choline and CoQ10 supplementation**

Choline is an essential nutrient that has to be derived from the diet. Although it can be synthesized in the body, this is not sufficient to support bodily needs [105, 106]. Choline supply is critical for brain development because it is a precursor of acetylcholine—a key neurotransmitter for regulating neuronal proliferation, maturation, plasticity, survival, and synapse formation. Besides this, choline is the precursor of phosphatidylcholine and sphingomyelin—principal components of neuronal and other cellular membranes. It is also a primary dietary source of methyl groups in humans [107]. It acts as a methyl donor through the betaine–methionine pathway. Alterations in the dietary levels of choline during early development can produce life-long effects on gene expression through DNA methylation [108].

Disturbances in the cholinergic system are likely due to alterations in acetylcholine metabolism with a significant relationship to AD-like symptoms in DS adults since an impaired acetylcholine metabolism has been reported in the brains of individuals with AD. A reduction in the cholinergic neurotransmitter choline acetyltransferase has also been reported in cortical and sub-cortical regions of DS adult brain tissues [53]. Cholinergic deficits in the brain are a hallmark in humans with DS and Ts16 mice. Brains of DS individuals exhibit a significant reduction in choline acetyltransferase activity in the cerebral cortex, which is consistent with the impaired development of the basal forebrain cholinergic system exhibited by Ts16 mice [109].

So far, there is no evidence that choline supplementation possibly improves cognitive functioning when given to young or adult individuals with DS [110]. On the other hand, several studies proved that perinatal choline supplementation in Ts65Dn mice has beneficial effects on Ts65Dn offspring, including improvements in attention, emotion regulation, spatial memory, and the protection of cholinergic neurons in the medial septal nucleus (MSN) [107, 108, 111]. Specific molecular mechanisms by which supplementing the maternal diet with additional choline exerts life-long effects on offspring functioning are not clear yet, and further studies are necessary [112]. It is believed that it enhances the target-derived neuroprotection of Ts65Dn basal forebrain cholinergic neurons (BFCNs), which typically begin to atrophy at six months of age due to the impaired retrograde transport of nerve growth factor (NGF) [108]. Although Ts65Dn mice do not show all the genetic and phenotypic features of DS, these findings suggest the interesting possibility that increased maternal choline intake during pregnancy may represent a safe and beneficial intervention at the earliest stages [107]. Nevertheless, results obtained in mice tests suggest that current dietary guidelines for choline (425 mg/day for women and450 mg/day for pregnant women) [106], which are necessary to prevent liver damage, may not be sufficient for brain development and higher levels should be taken during pregnancy [110].

Coenzyme Q10 (CoQ10) is lyophilic quinone that can be synthesized by an organism or introduced by the diet. His cell functions include antioxidant activity, carrying


#### **Table 4.**

*Examples of CoQ10 supplementation research for DS individuals.*

electrons in mitochondria, and serving as a cofactor to some enzymes [113]. There is a theory that CoQ10 could diminish oxidative DNA damage and serve as a therapy for issues related to DS. Research examples presented in **Table 4** show that an additional survey should be conducted in order to confirm this theory.

#### **6. Conclusions**

Education and encouragement of caregivers of people with DS to pay attention to the quality of nutrition should be the focus of professionals included in DS rehabilitation. Prevention of nutrient deficiency is certainly cheaper and more effective than dealing with supplementation. Since the metabolic pathways of people with DS are altered, they are more sensitive to nutrient deficiencies than the rest of the population. So, nutrient status should be a part of routine health screening and supplementation should be introduced only after deficiencies of certain nutrients have been identified. Supplementation should be introduced only as directed by a physician. Many research has shown promising results about the improvement of health status and intellectual development of individuals with DS, but the safety of doses and their efficiency have not been proved by independent scientific studies, especially in relation to the diet and nutrient status of DS individuals prior to supplementation.

### **Conflict of interest**

The authors declare no conflict of interest.

*Dietary Supplements - Challenges and Future Research*

#### **Author details**

Maja Ergović Ravančić and Valentina Obradović\* Polytechic in Požega, Vukovarska, Pozega, Croatia

\*Address all correspondence to: vobradovic@vup.hr

© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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#### **Chapter 3**

### Impact of Glycine Supplementation to Dietary Crude Protein Reduction in Broiler Chickens

*Paschal Chukwudi Aguihe, Ibinabo Imuetinyan Ilaboya and Deji Abiodun Joshua*

#### **Abstract**

A 21-day experiment was conducted to evaluate the effect of dietary reduction of crude protein (CP) concentrations with graded levels of supplemental glycine (Gly) on growth performance of broiler chickens. Day-old chicks (n = 250) were randomly divided into five treatment groups which were divided into five replicates of ten chicks each in a completely randomized design. The treatments were as follows: T1 comprised of the control group with a standard CP diet (SCPD; 3100 kcal ME/kg and 22% CP) while T2, T3, T4 and T5 comprised of groups fed reduced CP diets (RCPD; 3100 kcal ME/kg and 19% CP) with supplemental Gly at 0.2, 0.4, 0.6 and 0.8% graded levels, respectively. Weight gain (WG), feed intake (FI) and feed conversion ratio (FCR) data was collected on a weekly basis. Final body weight and weight gain of birds fed control and 0.8% Gly diets were similar and higher (P < 0.05) than those fed other treatment diets. A similar FCR was recorded among birds fed control, 0.6% and 0.8% Gly diets but lower (P < 0.05) than other treatment groups. Therefore, a minimum level of 0.6% Gly supplementation is necessary to optimized performance of broilers (21-d old) fed RCPD.

**Keywords:** broiler, low protein diet, glycine, performance, glycine supplementation

#### **1. Introduction**

The mounting demand of animal proteins for an expanding global population in the face of limited natural resources shall be guided by the responsibility to increase productivity while minimizing environmental impact. Leaving conventional animal feeding methods in the past and shifting to well establish modern dietary strategies could play a substantial role in securing a smaller ecological footprint from animal production. This means lowering dietary crude protein (CP) while supplementing essential amino acids (AA) to cover the nutritional requirements of the broilers. Growing emphasis on environmental regulation requires global animal production to adopt strategies like feeding low CP diets to minimize nitrogen (N) excretion. Furthermore, N excretion declines by approximately 14% providing strong environmental incentives to successfully reducing CP in broiler

feeds by greater than 30 g/kg [1–3]. The formulation of these diets is typically based on decreases in soybean meal and increases in feed grain (maize or wheat) contents coupled with elevated inclusions of non-bound (crystalline and synthetic) amino acids to meet requirements. Real benefits for sustainable chicken-meat production using less resources will stem from the successful development of such diets. There is a genuine quest to develop effective, reduced crude protein (CP)-diets for broiler chickens because their acceptance would generate several material advantages. These advantages range from reduced nitrogen and ammonia emissions, improved litter quality and enhanced bird welfare to less undigested protein passing into the hind gut to fuel the proliferation of potential pathogens [4, 5]. Furthermore, a reduction in dietary CP may improve flock health by reducing the risk of necrotic enteritis (NE) caused by the proliferation of *Clostridium perfringens* in the hind gut [6, 7]. The economic benefits of reducing dietary CP stem from reductions in energy expenditure on excreting excess N as uric acid and sparing of matrix space in feed formulation for inclusion of less energy dense ingredients, potentially reducing feed costs [8]. Besides, reducing dietary CP has a particular advantage for producers in tropical and subtropical regions especially sub-sahara Africa; where heat stress is a common problem in poultry production, and causes major economic losses annually [9, 10]. Given the fact that heat increment of CP is the highest, compared to fat and carbohydrates [11], it has been proposed that the adverse effects of heat stress on poultry performance can be alleviated by reducing CP [12, 13].

However, in some of the animal feeding studies, lowering dietary CP beyond a certain level showed undesirable effects on growth performance and carcass quality of broilers [14–17]. Whilst greater reductions of dietary CP (40 to 50 g/kg) invariably compromise broiler performance and increase lipid deposition, a limited number of studies have investigated both aspects [16, 18, 19]. Thus, inferior FCR and increased fat deposition epitomize the challenges to successfully reducing dietary CP using substantial levels of non-bound amino acids. Such findings imply that there is a threshold to CP reductions that can be accommodated by broiler chickens. If the factors contributing to this threshold were to be identified it should be possible to put corrective strategies in place so that tangibly reduced-CP diets, with their attendant advantages, will meet acceptance.

A number of explanatory approaches or reasons have been advanced or debated as the possible consequences of tangibly lowering dietary CP on broiler performance [20]. The difference in the optimal ratio of essential AA between experimental diets [21], specific non-essential AA [22] and utilization of free AA compared to peptide bound AA [16] are among the approaches mostly discussed. Considering the sum of nonessential amino acids probably is not sufficient because specific metabolic processes can become limiting [23]. This leads to the implication that single nonessential amino acids are important to avoid unfavorable effects of low crude protein feed on the growth of broiler chickens [24, 25]. Single nonessential amino acids have been supplemented to low crude protein feed in several studies. Supplementing free glutamic acid, aspartic acid, proline, and alanine consistently did not prevent from reduced growth caused by feeding low crude protein feed [26, 27]. However, growthincreasing effects were determined when free glycine was supplemented. Two studies showed that supplementing feed with a crude protein concentration of 16% with free glycine to the level of about 22% crude protein control feed prevented reduction of growth compared to the control feed [27–29].

However, the concentration of glycine in nutrition of broiler chickens cannot be considered alone because studies revealed that serine in the feed has the same effect *Impact of Glycine Supplementation to Dietary Crude Protein Reduction in Broiler Chickens DOI: http://dx.doi.org/10.5772/intechopen.106786*

on the growth as glycine [30]. Animals can convert glycine into serine and vice versa. On a molar basis, serine is considered to be as effective as Gly for various functions in poultry due to the inter-conversion between the two amino acids [30]. Owing to their assumed unlimited metabolic inter-conversion, Gly and Ser are usually assessed simultaneously when determining the physiological value of diets. Most studies use the sum of both Gly and Ser concentrations, usually termed 'Gly + Ser' to capture the analogous effect of these AAs. Therefore, this study was carried out to evaluate the impact of reducing crude protein concentration with feed-grade glycine supplementation in corn-soybean based diet of broiler chicken on growth performance during the period of 1–21 days of age.

#### **2. Materials and method**

#### **2.1 Husbandry and treatments**

A total of 250 day old mixed-sex broilers (Arbor acre) with comparable initial body weights were raised at 10 chicks/replicate in a deep litter pens under standard environmental and hygienic practices from day 1 to 35. They were acquired from a reputable commercial hatchery and immunized at the hatchery following a vaccination regime for Arbor acre strain. Birds had free access to mash feed and freshwater during the course of the trial. Feeds (**Table 1**) based on corn and soybean for starter (1–21 days) phase were prepared according to the recent NRC broiler chicken's nutritional requirements except for CP. The experiment was performed as a completely randomized design with five dietary treatments arranged in five replications of 10 chicks each. The treatments were as follows: T1 comprised of the control group with a standard CP diet (SCPD) while T2, T3, T4 and T5 comprised of groups fed reduced CP diets (RCPD) with supplemental Gly at 0.2, 0.4, 0.6 and 0.8% graded levels respectively. Diets (mash) and water were provided ad libitum throughout the experiment. All experimental diets were made isocaloric to contain 3100 kcal ME/kg; whereas, SCPD was formulated to contain 22% CP and the RCPD were isonitrogenous to contain 19% CP for T2 – T5. The feed formulation and nutritional composition of the starter (1–21 days of age) diets are shown in **Table 1**. Dietary treatment groups were set up in an alternating pen pattern within the facility. All birds were housed in the Poultry Research Facility of the Department of Animal Production and Health Technology at the Federal College of Wildlife Management, New Bussa, Niger state, Nigeria. All animals were maintained according to the guidelines specified by the Research Committee Council on Animal Care, and protocols were approved by the Federal College of Wildlife Management Animal Care and Use Committee.

#### **2.2 Sampling and measurements**

Body weight (BW) was measured weekly for each pen. Feed intake was determined as the difference between the amount of feed offered and the amount unconsumed in starter and grower phase. The daily feed intake (DFI) was calculated by dividing each pen's consumed feed on starter and grower phase by actual total number of birds. The feed conversion ratio (FCR: g feed/g body weight gain) was calculated by dividing daily feed intake by daily body weight gain. On day 35, two birds per replicate with a BW close to the pen average weight were chosen, and the blood for biochemical analyses was taken from the jugular vein and centrifuged at 3000 rpm for


*a Vitamin/Mineral Premix supplied per kg of the diet: Vit A: 10,000iu; Vit D: 28000iu; Vit E: 35,000iu; Vit K: 1900 mg; Vit B12: 19 mg; Riboflavin: 7000 mg; Pyridoxine: 3800 mg; Thiamine: 2200 mg; Pantothenic acid: 11000 mg; Nicotinic acid: 45,000 mg; Folic acid: 1400 mg; Biotin: 113 mg; Cu: 8000 mg; Mn: 64000 mg; Zn: 40, 000 mg; Fe: 32000 mg; Se: 160 mg; Iodine: 800 mg; Cobalt: 400 mg; Choline: 475000 mg.*

*b SCPD: Standard crude protein diet.*

*c RCPD: Reduced crude protein diet.*

*d ME: Metabolizable energy.*

#### **Table 1.**

*Ingredients composition and nutrient levels of experimental diets (% as fed).*

*Impact of Glycine Supplementation to Dietary Crude Protein Reduction in Broiler Chickens DOI: http://dx.doi.org/10.5772/intechopen.106786*

10 min to separate serum that was stored at -80°C. The serum concentrations of total protein, albumin, glucose, triglyceride, and creatinine were determined by utilizing enzymatic colorimetric kits as specified by the manufacturer. Serum globulin was estimated accordingly by subtracting albumin from total protein.

#### **2.3 Statistical analysis**

The statistical processing of the results was done using general linear model (GLM) of SPSS, version 20.0 (SPSS Inc., Chicago, IL, USA). When comparing treatments means, post hoc Tukey's multiple range test was carried out to assess any significant differences for the measured parameters. Differences were considered significant at p < .05. Replicate-pen was used as the experimental units for the analysis.

#### **3. Result and discussion**

Growth performance of the broiler chicks fed RCPD containing graded levels of supplemental glycine are shown in **Table 2**. At day 21, the results of the present study showed that glycine supplementation did not affect (P > 0.05) the initial body weight and feed intake, however, significant differences (P < 0.05) were observed on final body weight, weight gain and FCR of the broiler chicks. Chicks fed control diet had higher (p < 0.05) final body weight and weight gain than the chicks fed RCPD with 0.2, 0.4 and 0.6% supplemental glycine levels. Similar (p > 0.05) final body weight and weight gain were observed among chicks fed control diet and 0.8% Gly supplemented RCPD. Birds fed control, 0.6 and 0.8% Gly diets have similar (p > 0.05) feed conversion ratio, and were lower (p < 0.05) than those on RCPD with 0.2 and


*a Means within column with no common superscripts differ significantly (p < 0.05).*

*b Means within column with no common superscripts differ significantly (p < 0.05).*

*c Means within column with no common superscripts differ significantly (p < 0.05).*

*d Means within column with no common superscripts differ significantly (p < 0.05).*

*T1: Standard crude protein diet (Control).*

*T2: Reduced crude protein diet +0.2% glycine.*

*T3: Reduced crude protein diet +0.4% glycine.*

*T4: Reduced crude protein diet +0.6% glycine.*

*T5: Reduced crude protein diet +0.8% glycine.*

*SEM: Standard Error Mean.*

#### **Table 2.**

*Growth performance of broiler chicken (1–21 d old) fed reduced crude protein diets with graded levels of supplemental glycine.*

0.4% Gly diet. The present study showed that increasing levels of supplemental Gly increased weight gain and decreased feed conversion ratio among the experimental birds. Gly addition at 0.2 and 0.4% levels which provided 1.98 and 2.18% total Gly + Ser, respectively in the diets failed to completely overcome the adverse impact of dietary reduction of CP by 3% on the performance of the broiler chickens at 21 d old. This observation corroborates with the findings of Awad et al. [30] who concluded that the provision of 2.02–2.22% dietary Gly + Ser during starter period failed to support optimal growth performance in broiler chickens raised under tropical climate. However, providing 2.36 and 2.56% total Gly + Ser concentration in the RCPD through increased supplementation of Gly at 0.6 and 0.8% levels were observed to restored the FCR to equal those group fed control diet.

This present finding is in agreement with the reports of previous researchers [18, 27, 31, 32] who confirmed that maintaining a minimum level of 2.32% in diets via Gly supplementation allowed to decreased dietary CP concentration up to 3% or more without compromising the accumulative growth performance of broiler chickens (1–21 d old). Also, our result is in accordance with previous reports which suggested that maintenance of optimal amino acid ratios for essential amino acids and sufficient total Gly + Ser levels appear most important considerations in formulating broiler diets with reduced CP concentrations [2, 25, 33–35]. According to Kamely et al. [35], feeding low protein diets formulated to provide higher Gly + Ser and meet digestible amino acid requirements could be an efficient way to reduce nitrogen excretion to the environment and decrease feed cost without impacting growth performance. Also, the current result concur with the report of Siegert et al. [22], who conducted a meta-analysis of 10 studies and concluded that sufficient supply of dietary Gly + Ser had significant positive effects on weight gain and feed conversion efficiency of birds fed low CP diets. Understanding the active roles play by Gly in several number of non-protein pathways can further account for the reasons why it can potentially improve the performance of broiler chickens supplied with RCPD [36, 37]. Gly plays significant function for methionine recycling and cysteine biosynthesis, threonine catabolism, uric acid and creatine synthesis [38]. Moreover, Gly represents the main part of the gut mucin glycoproteins [39]. In essence, Gly can promote the metabolic and nutritional efficiency of EAA as well as gut functionality and consequently growth performance [13, 40, 41]. In view of these key metabolic roles of Gly, although it is notionally a non-essential amino acid; Gly may become conditionally limiting in reduced CP diets formulated based on vegetable ingredients [41–43]. Provision of higher dietary level of Gly + Ser via increased Gly supplementation may be essential to achieve greater CP reduction without compromising the growth performance of growing broiler chickens [13, 32, 40].

#### **4. Conclusion and recommendation**

In the present study, increasing dietary levels of glycine supplementation resulted in an increased body weight gain and improved feed conversion ratio of broiler chicks fed diets containing reduced crude protein concentration. Maintaining a minimum of 0.6% supplemental Gly that provided 2.36% Gly + Ser level has shown to support the reduction of crude protein concentration from 22 to 19% in diet of broiler chickens at 21 days of age, without undermining their accumulative growth performance and concomitantly minimizing the impact of broiler production on the environment. Therefore, higher Gly supplementation (0.6–0.8% inclusion) can be recommended

#### *Impact of Glycine Supplementation to Dietary Crude Protein Reduction in Broiler Chickens DOI: http://dx.doi.org/10.5772/intechopen.106786*

for the initial stages of growth of broiler chickens up to 21 d of age, based on weight gain and feed conversion responses raised under tropical environment.

As Gly have the potential to limit growth performance of broiler chickens, this amino acid, ideally on a digestible basis, should appear in recommendations suitable for facilitating low CP diets, because such diets are expected to become more important in the future. Growing evidence in the present study shows that a sufficient provision of supplemental glycine is necessary for the optimal growth of chickens. Thus, ideal protein diets for poultry must supply all physiologically and nutritionally amino acids to maximize their growth performance and productivity. This nutritional strategy is expected to facilitate the formulation of low-protein diets and precision nutrition through the addition of low-cost supplemental amino acids or their alternative sources of animal proteins. In regions where free crystalline glycine is prohibited or not approved, an adequate dietary Gly + Ser supply can only be achieved by inclusion of feedstuffs of animal origin which represent good source of glycine, to prepare balanced low protein diets for chickens and help sustain the global animal agriculture for increased food productivity. Thus, in our study, dietary crude protein was reduced with supplemental glycine fortification up to 3% without any adverse effects on broiler performance. So, in future, when amino acid industry expanded and all nutritional amino acids distributed as feed grade supplements for animal use, it could be possible reduce crude protein up to 6% which will be more economic. If progress in these directions can be actualized, then the prospects of reduced protein diets contributing to sustainable chicken-meat production are promising and becomes increasingly real.

#### **Acknowledgements**

The authors wish to acknowledge the support of the management of Federal College of Wildlife Management, New Bussa, Nigeria, towards the success of this research project.

#### **Conflict of interest**

The authors declare that they have no conflicts of interest associated with this manuscripts.

#### **Author details**

Paschal Chukwudi Aguihe1 \*, Ibinabo Imuetinyan Ilaboya2 and Deji Abiodun Joshua3

1 Department of Animal Production Technology, Federal College of Wildlife Management, New Bussa, Nigeria

2 Department of Animal Science, Benson Idahosa University, Benin, Nigeria

3 Department of Basic Science, Federal College of Wildlife Management, New Bussa, Nigeria

\*Address all correspondence to: aguihepc@gmail.com

© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Impact of Glycine Supplementation to Dietary Crude Protein Reduction in Broiler Chickens DOI: http://dx.doi.org/10.5772/intechopen.106786*

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[16] Macelline SP, Chrystal PV, Liu SY, Selle PH. Implications of elevated threonine plasma concentrations in the development of reduced-crude protein diets for broiler chickens. Animal Production Science. 2021;**61**:1442-1448

[17] Wang WW, Wang J, Wu SG, Zhang HJ, Qi GH. Response of broilers to gradual dietary protein reduction with or without an adequate glycine plus serine level. Italian Journal of Animal Science. 2020;**19**(1):127-136

[18] Hilliar M, Hargreave G, Girish CK, Barekatain R, Wu SB, Swick RA. Using crystalline amino acids to supplement broiler chicken requirements in reduced protein diets. Poultry Science. 2020;**99**:1551-1563. DOI: 10.1016/j. psj.2019.12.005

[19] Aftab U, Ashraf M, Jiang Z. Low protein diets for broilers. World's Poultry Science Journal. 2006;**62**:688-701

[20] Kobayashi H, Nakashima K, Ishida A, Ashihara A, Katsumata M. Effects of low protein diet and low protein diet supplemented with synthetic essential amino acids on meat quality of broiler chickens. Animal Science Journal. 2013;**84**(6):489-495. DOI: 10.1111/ asj.12021

[21] Corzo A, Kidd MT, Burnham DJ, Kerr BJ. Dietary glycine needs of broiler chicks. Poultry Science. 2004;**83**:1382-1384

[22] Siegert W, Ahmadi H, Rodehutscord M. Meta-analysis of the influence of dietary glycine and serine, with consideration of methionine

and cysteine, on growth and feed conversion of broilers. Poultry Science. 2015;**94**(1853):e63

[23] Waldroup PW. Do crude protein levels really matter? In: Proc. 15th Annual ASAIM Southeast Asian Feed Technology and Nutrition Workshop. Conrad Bali Resort, Indonesia; 2007. pp. 1-5

[24] Chrystal PV, Moss AF, Yin D, Khoddami A, Naranjo VD, Selle PH, et al. Glycine equivalent and threonine inclusions in reduced-crude protein, maize-based diets impact on growth performance, fat deposition, starchprotein digestive dynamics and amino acid metabolism in broiler chickens. Animal Feed Science and Technology. 2020;**261**(114837):1e14

[25] Saleh AA, Amber KA, Soliman MM, Soliman MY, Morsy WA, Shukry M, et al. Effect of low protein diets with amino acids supplementation on growth performance, carcass traits, blood parameters and muscle amino acids profile in broiler chickens under high ambient temperature. Agriculture. 2021;**11**:185-197

[26] Dean DW, Bidner TD, Southern LL. Glycine supplementation to low protein, amino acid supplemented diets supports optimal performance of broiler chicks. Poultry Science. 2006;**85**(288):e96

[27] Awad EA, Zulkifli I, Soleimani AF, Loh TC. Individual non-essential amino acids fortification of a low-protein diet for broilers under the hot and humid tropical climate. Poultry Science. 2015;**94**:2772-2777

[28] Baghban-Kanani P, Azimi-Youvalari S. Interactive effects of glycine and threonine in low protein broiler diets on performance, blood ammonia level, intestinal mucosa development

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and nutrient digestibility. Acta Scientific Veterinary Sciences. 2022;**4**(1):1-2

[29] Sugahara M, Kandatsu M. Glycine serine inter-conversion in the rooster. Agricultural and Biological Chemistry. 1976;**40**:833-837

[30] Awad EA, Zulkifli I, Soleimani AF, Aljuobori A. Effects of feeding male and female broiler chickens on low-protein diets fortified with different dietary glycine levels under the hot and humid tropical climate. Italian Journal of Animal Science. 2017;**16**:453-461

[31] Aguihe PC, Ospina-Rojas IC, Sakamoto MI, Pozza PC, Iyayi EA, Murakami AE. Dietary glycine equivalent and standardized ileal digestible methionine + cysteine levels for male broiler chickens fed low-crude-protein diets. Canadian Journal of Animal Science. 2022;**102**(1):19-29. DOI: 10.1139/ CJAS-2021-0009

[32] Lemme A, Hiller P, Klahsen M, Taube V, Stegemann J, Simon I. Reduction of dietary proteinin broiler diets not only reduces n-emissions but is also accompanied by several further benefits. Journal of Applied Poultry Research. 2019;**28**:867-880. DOI: 10.3382/japr/ pfz045

[33] Hofmann P, Siegert W, Kenéz Á, Naranjo VD, Rodehutscord M. Very low crude protein and varying glycine concentrations in the diet affect growth performance, characteristics of nitrogen excretion, and the blood metabolome of broiler chickens. Journal of Nutrition. 2019;**149**:1122-1132. DOI: 10.1093/jn/ nxz022

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[39] Ospina-Rojas IC, Murakami AE, Eyng C, Nunes RV, Duarte CRA, Vargas MD. Commercially available amino acid supplementation of lowprotein diets for broiler chickens with different ratios of digestible glycine+serine: Lysine. Poultry Science. 2012;**91**:3148-3155. DOI: 10.3382/ ps.2012-02470

[40] Ospina-Rojas IC, Murakami AE, Moreira I, Picoli KP, Rodrigueiro RJB, Furlan AC. Dietary glycine+serine responses of male broilers given low-protein diets with different concentrations of threonine. British Poultry Science. 2013;**54**:486-493

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#### **Chapter 4**

### DHA (Docosahexaenoic Acid): A Biomolecule with Diverse Roles and Health Benefits

*Abdul Hei and Laishram Sanahanbi*

#### **Abstract**

With the increasing interest in health and nutrition for longevity of life and more performance ability, the idea of health foods and nutrients has attracted more research and studies. Omega-3 fatty acid docosahexaenoic acid (DHA) is a nutrient molecule with various diverse roles and health benefits in the human body. Though DHA originally comes from microalgae and sea plants, the main source of DHA is fish, shellfish, and fish oils. DHA is a key nutrient with a structural and functional role in the cell membrane and cell organelles, and abundant in brain and eye. It is good for the heart, and protective against heart diseases. It is rather a very ancient molecule with more modern concepts. Really, DHA has been proven to be a key nutrient that is required in the processes of physical and mental development and health, and prevention of diseases throughout the life span. Driven by the values of physical and mental health, the demand for DHA in the international market is expected to grow. This review is an attempt to update the research findings about DHA and its health benefits in an easy and lucid way.

**Keywords:** DHA, fish oils, diseases prevention, health, more ability

#### **1. Introduction**

Everybody on this planet would like to lead a beautiful, happy, and meaningful life. However, we are what we eat. A sound body and a sound mind come from what we are made up of. So, a perfect knowledge of what we intake daily in our diet and especially in the stages of pregnancy, infancy, and childhood is very important. Interest in omega-3 fatty acids has increased in recent years because of their various roles in health promotion and disease risk reduction [1]. With increasing interest in health consciousness and our well-being, the essential omega-3 fatty acids have been the most studied biomolecules during the last few decades. These omega-3 fatty acids have strong implications in medicine as they have been linked to various health conditions, such as inflammation, cancer, heart diseases, and neurological disorders. Docosahexaenoic acid DHA is the key component of all cell membranes of the body and the most important fatty acid, which is concentrated in the brain and central nervous system and is referred to as "brain food." On account of its diverse amazing roles and health benefit, it has become the star nutrient molecule nowadays [2]. Bradburry call the DHA molecule an ancient molecule for the modern human brain [3].

An optimum level of the omega-3 fatty acid DHA in the body is required for efficient body functions. Omega-3 fatty acids have been linked to healthy aging throughout life [4]. As these PUFA are essential, normal infant/neonatal brain, intellectual growth, and development cannot be accomplished if they are deficient during pregnancy and lactation. Sustaining normal adult brain function also requires PUFA.

Studies suggest that the evolution of large human brain occurred depending on the rich source of preformed long-chain PUFA at the interface of land and water. The human diet has changed to a large extent during the last 100 years. One of the striking changes is the enormous increase in dietary fat. In terms of quality, we have increased our intakes of saturated fatty acids (SFA), alpha-linoleic acid (LA) and *trans* fatty acids, concomitant with reduced intakes of (n-3) fatty acids. The latter comprises reduced intake of 3-linolenic acid (ALA) rich foods, and less consumption of long-chain PUFA of the (n-3) series [LC(n-3)P], that is, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids notably from fish [1]. These dietary and other environmental changes are deemed to be among the major causes of the rapid expansion of diet-related chronic disease [2], including cardiovascular disease (CVD) in the past century [5].

The question is: Are we getting enough of the DHA in our daily diet? DHA is found mainly in seafood, such as fish, shellfish, and fish oils. It is also found in some types of algae [6]. So, the objective of the chapter is to review and discuss the diverse amazing health benefits and roles and to make sure if we are getting enough DHA in our diet.

#### **2. Defining DHA: one biomolecule diverse functions**

DHA (docosahexaenoic acid) is an important omega -3 polyunsaturated fatty acid (PUFA) consisting of a long chain of 22 carbon atoms and 6 double bonds. DHA is mainly found in fish and fish oil with EPA. It is remarkable that one simple molecule has been reported to affect so many apparently unrelated biological processes.

DHA molecule is an integral part of all cell membranes and critical to membrane fluidity [7]. Aptly referring to "DHA as brain food," docosahexaenoic acid (DHA) is the predominant omega-3 (n-3) polyunsaturated fatty (PUFA) found in the brain and can do neurological function through signal transduction, pathway, neurotransmission, neurogenesis, membrane receptor function, synaptic plasticity, healthy inflammation balance, membrane organization, and membrane integrity [8].

Important functions of DHA include antioxidant activity, memory formation, neurogenesis, acting as a signaling molecule. Researchers conclude that it is fairly astonishing how DHA, a single molecule, plays so many roles. The present-day diet typically lacks appreciable amounts of DHA. Therefore, in modern population maintaining optimal levels of DHA in the brain throughout the lifespan likely requires obtaining preformed DHA *via* dietary supplemental sources. Most omega-3 supplements contain both DHA and EPA but there are many high-quality DHA supplements also available when more of this precious nutrient is desirable.

#### **3. Sources of DHA**

Important omega-3 fatty acids are DHA, EPA, and ALA. Polyunsaturated fatty acids, particularly n-3 PUFA, DHA, and EPA are the prominent compounds found in fish [9]. ALA is present in different plant seeds and grains that convert a small amount into EPA and DHA after human consumption. Flaxseed oil is a major

*DHA (Docosahexaenoic Acid): A Biomolecule with Diverse Roles and Health Benefits DOI: http://dx.doi.org/10.5772/intechopen.109677*

plant source of ALA [10]. In the human diet, the main contributors of DHA and EPA are marine ecosystems (fish, shellfish, and other sea foods) [11]. Fish liver contains a large number of omega-3 fatty acids that have been proven by different studies to lower blood triglycerides and cholesterol levels. Actually, fatty predatory fish like sharks have a lot of omega-3 fatty acids in their tissues that possess a lot of health benefits, particularly in terms of reducing inflammation, improving mental health, and serving as an antioxidant [11]. Fatty fishes, such as *Salmo salar* (salmon *Gadus morhua* (cod), *Thunnus thynnus* (tuna),) *Tenualosa ilisha, Sardinella longiceps, Schizothorax richardsonii*, and *Neolisochilus hexaganolepis,* have numerous roles as main sources of DHA and other polyunsaturated fatty acids [12]. Micro- and macroalgae are original sources of DHA [13]. Another study stated that egg yolk contains ALA (0.8%), DHA (0.7%), and EPA (0.1%). Additionally, egg yolk, lean red meat, chicken, and human milk are also good sources of ALA [14].

#### **4. Reason for intake of DHA in our diet**

Human body cannot synthesize enough amount of DHA from α-linolenic acid (ALA), under the actions of fatty acid elongases and desaturases, the bioconversion rate in the human body is extremely low, generally at 2–10%), and sometimes, it was reported even at a lower rate of 0.01%. Therefore, DHA-rich or fortified foods and DHA supplements are the two main exogenous sources to obtain additional DHA needed for the biological functions of human body [15].

Important roles of DHA are found in **Figure 1.**

1. Eyes, 2. Brain, 3. Heart, 4. Developing infants and children, 5. Bones, 6. Joints, 7. Skin, and 8. Spermatozoa (**Figure 1)**.

Docosahexaenoic acid (DHA) is essential for the growth and functional development of the brain in infants. DHA is also needed for the maintenance of normal brain function in adults. The inclusion of plentiful DHA in the diet boosts learning ability,

#### **Figure 1.**

*Picture showing important benefits of DHA.*

whereas deficiencies of DHA are associated with deficits in learning. DHA deficiencies are also associated with fetal alcohol syndrome, attention deficit hyperactivity disorder, cystic fibrosis, phenylketonuria, unipolar depression, aggressive hostility, and adrenoleukodystrophy [16]. Decreases in DHA in the brain are correlated with cognitive decline during aging and with the onset of sporadic Alzheimer's disease.

Several researchers have shown that ω-3 PUFAs play a major role in altering blood lipid profiles and membrane lipid composition and affect eicosanoid biosynthesis, cell signaling cascades, and gene expression, thereby influencing health [17, 18]. In addition, the beneficial effect of ω-3 PUFAs in patients with myriad health conditions and diseases, such as cardiovascular disease (atrial fibrillation, atherosclerosis, thrombosis, inflammation, and sudden cardiac death, among others), diabetes, cancer, depression and various mental illnesses, age-related cognitive decline, periodontal disease, and rheumatoid arthritis, has been investigated [19, 20].

#### **5. Brain development during pregnancy and early life**

Controlling and shaping a child's destiny should start from the stage of pregnancy. Nutrition in pregnancy, during lactation, childhood, and later stages has an important influence on overall development. DHA is a bioactive omega-3 polyunsaturated fatty acid that influences membrane structure and function, cell signaling and communication mechanisms, gene expression, and lipid mediator production. DHA is found in high concentrations in the human brain and eye, where it is linked to better development and function. Maintenance of DHA concentration is important throughout the life course, but pregnancy, lactation, and infancy are vulnerable periods, whereas insufficient DHA supply can impact mental and visual development and performance [21].

Docosahexaenoic acid, 22:6n-3 (DHA), is crucially necessary for the structure and development of the growing fetal brain in utero. DHA is the dominant n-3 long-chain polyunsaturated fatty acid in brain gray matter representing about 15% of all fatty acids in the human frontal cortex. DHA has roles in neurogenesis, neurotransmitter, synaptic plasticity and transmission, and signal transduction in the brain. Data from human and animal studies indicate that adequate levels of DHA in neural membranes are required for the maturation of cortical astrocyte, neurovascular coupling, and glucose uptake and metabolism. Besides, some metabolites of DHA are protective against oxidative tissue injury and stress in the brain. A low DHA level in the brain produces behavioral changes and is associated well with learning difficulties and dementia. In humans, the third trimester-placental supply of maternal DHA to the growing fetus is crucially important as the growing brain obligatorily needs DHA during this window period. Moreover, DHA takes part in the early placentation process, essential for placental development [22].

Docosahexaenoic acid has a rapid accumulation in the brain from week 30 of pregnancy to 2 years postpartum. About 67 mg of DHA is accrued by the fetus per day, thereby increasing its brain weight and making it important for the mother to have adequate DHA intake during this time. The DHA accretion during lactation is 70–80 mg/day, and this huge demand for DHA during lactation depletes maternal stores and may take months to recover even partially [14]. The increasing concentration of DHA takes place nearly 30-fold during the growth spurts of the brain, which corresponds to the beginning of the third trimester of pregnancy to 18 months after birth [23]. During these early growth spurts, the brain is critically vulnerable to nutritional deficiencies. Preterm infants much miss out on the chance of DHA accretion

#### *DHA (Docosahexaenoic Acid): A Biomolecule with Diverse Roles and Health Benefits DOI: http://dx.doi.org/10.5772/intechopen.109677*

during the last trimester and thus would benefit from external supplementation [24]. Arachidonic acid begins accretion in the brain during the last trimester of pregnancy and continues to accumulate until 2 years of postnatal age. Accretion of about 95 mg/ day of ARA takes place during the last 5 weeks of gestation; this is nearly twice the amount of DHA accrued during the same period. A larger amount of the ARA is accumulated in the adipose tissue and skeletal muscles, with relatively lesser amounts accumulated in the brain [25].

A supply of DHA is very important early in life, especially during the fetal and early infant periods when the eye and central nervous system are developing. During pregnancy, transfer of DHA including EPA is done through the placenta from mother to the fetus [26]. The level of omega-3 fatty acid in the fetus is correlated with the amount ingested by the mother, so it is essential that the mother has adequate nutrition [4]. The function of DHA in the brain is to support the transmission of messages through nerve cells and to protect the brain against the loss of scaffolding proteins and oxidative degradation of lipids, thus helping maintain the plasticity of the brain [27]. DHA also plays a functional role in gene expression, myelination, and growth and differentiation of neurons [28]. DHA is also a basic membrane component of the photoreceptor cells of the eye, and proper functioning of the photoreceptor cells is essential for vision [29, 30]. Arachidonic acid is an omega-6 (n-6) fatty acid that plays important roles in brain functioning, including neuronal firing, signal transmission, and long-term potentiation. Besides, ARA preserves hippocampal neuron membrane plasticity, protects the brain against oxidative stress, and aids in the synthesis of new proteins in brain tissues [31].

EPA and DHA supplementation during pregnancy has been found with multiple benefits for the infant. Numerous studies confirmed the benefit of omega-3 supplementation during pregnancy in terms of proper development of the brain and retina. Of the two most important long-chain omega-3 fatty acids, EPA and DHA, DHA is the more crucial for proper cell membrane function and is vital to the development of the fetal brain and retina [32].

#### **6. DHA supplementation after birth**

The need for adequate DHA intake for women does not stop after the birth of a healthy baby. DHA goes on rapidly to accumulate in the brains of infants and young children through at least the second year of life [33]. However, human infants can only synthesize DHA in very limited amount, making them dependent on dietary sources, such as breast milk, formula, or DHA supplements [34].

It has long been known that breastfed infants have higher IQs and more advanced cognition than bottle-fed babies [35, 36]. It is now clearly known that one reason for this difference may be that breast milk normally contains DHA. Like the placenta, the milk-producing apparatus in the human breast routinely pulls DHA and other brainnourishing fatty acids from the mother's blood in preference to other fats, delivering the highest possible amounts to the breastfed infant. Again, this result can come at the expense of the mother's own DHA supplies if steady intake is not assured. The DHA content of the maternal diet is the most important factor determining how much DHA is found in breast milk. Some experts have raised concerns that the consumption of otherwise healthy low-fat diets by women of reproductive age could reduce the amount of DHA available to them during pregnancy and lactation [37]. Given the known low levels of DHA in most women's diets, this observation strongly suggests that DHA supplementation in nursing mothers is critical to optimizing brain development in their infants. DHA supplementation by nursing mothers increases the DHA content in their milk and in infant red blood cells, which is associated with enhanced visual acuity at 4 months [38, 39] and early language development in breastfed infants [33]. High maternal DHA intake is also associated with improved long-term growth in breastfed children [40–42]. Longer duration of breastfeeding and higher ratios of DHA to arachidonic acid (a precursor to DHA) was associated with higher total IQ scores in these school-aged children. The DHA that gets stored in the brain during infancy is an essential building block for children's cognitive, social, emotional, and behavioral development. Higher levels of DHA in infants are connected to stronger development of language, cognition, social, and motor skills as they move out of infancy and into young childhood [32].

#### **7. DHA and inflammation**

The role of omega-3 (EPA + DHA) in promoting the resolution of inflammation is an exciting development. Immunity, inflammation, and metabolic health are interrelated. Inflammation drives poor metabolic health. Inflammation leads to morbidity and mortality. Specific nutritional strategies can target inflammation to improve metabolic health. These same strategies target immunity—P.C. Calder.

Inflammation is a key component of normal host defense mechanisms initiating the immune response and later playing a role in tissue repair. Inappropriate, excessive, or uncontrolled inflammation contributes to human diseases and is believed to play a central role in many of the chronic diseases that characterize modern society [43–45].

Fatty acids can give influence on inflammation through a variety of mechanisms, including acting *via* cell surface and intracellular receptors/sensors that control inflammatory cell signaling and gene expression patterns. Some effects of fatty acids on inflammatory cells seem to be mediated by, or at least are associated with, changes in the fatty acid composition of cell membranes. Alterations in these compositions can modify membrane fluidity, lipid raft formation, cell signaling leading to altered gene expression, and the pattern of lipid and peptide mediator production [43, 45]. Cells within the inflammatory response are typically rich in the n-6 fatty acid arachidonic acid, but the contents of arachidonic acid and of the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can be altered through oral administration of EPA and DHA. Eicosanoids produced from arachidonic acid have inflammatory roles [45, 46]. EPA also produces eicosanoids and these may have differing properties from those of arachidonic acid-derived eicosanoids. EPA and DHA produce resolvins that are anti-inflammatory and inflammation-resolving. Thus, fatty acid exposure and the fatty acid composition of human inflammatory cells have an impact on their function. As a result of their anti-inflammatory actions, marine n-3 fatty acids have healing roles in rheumatoid arthritis, although benefits in other inflammatory diseases and conditions have not been unequivocally demonstrated [45, 46]. The anti-inflammatory effects of marine n-3 fatty acids may contribute to their protective roles toward atherosclerosis, plaque rupture, and cardiovascular mortality. The role of resolvins and related compounds may be very important because the resolution of inflammation is important in shutting off the ongoing inflammatory process and in limiting tissue damage [44]. Human trials show the benefits of oral n-3 fatty acids in rheumatoid arthritis and in stabilizing advanced atherosclerotic plaques. Intravenous n-3 fatty acids may be useful in critically ill patients through reduced inflammation. The anti-inflammatory and inflammation-resolving actions of EPA, DHA, and their derivatives are of clinical relevance [47].

*DHA (Docosahexaenoic Acid): A Biomolecule with Diverse Roles and Health Benefits DOI: http://dx.doi.org/10.5772/intechopen.109677*

Evidence suggests that, in addition to the amount of fat, the types of fats consumed can have a differential impact on human health. Their results on the risk of cardiovascular disease have dominated the rationale for these recommendations for the past 50 years [48]. There is increasing recognition by leaders in the nutrition and health field that dietary fats can affect host inflammatory responses [15].

#### **8. DHA and cardiovascular disease**

CVD is the leading cause of mortality in the world. For example, the prevalence of CVD in China is still rising [49] and India has a much higher rate of 272 per 10,000 higher than that of the global average of 235 [50]. AHA 2022 reports that CVD is the leading cause of death in America [7]. Some researchers have shown that n-3 fatty acids play a role in the protection against cardiovascular heart disease [51], sudden coronary death [52, 53], and peripheral arterial disease [54]. In addition, n- 3 omega-3 fatty acids have multiple beneficial effects on reducing cardio-metabolic risk factors, including dyslipidemia [55], increased blood pressure [56], arterial compliance [55], inflammation [57, 58] and vascular reactivity [59]. A recent meta-analysis showed that there were 9% and 13% risk reductions in coronary heart disease (CHD) events and myocardial infarction, respectively, with 1 g/day DHA supplements, and the effects were dose-dependent [60].

Earlier studies were done on the benefits of n- 3 LCPUFA in preventing CVD using a combination of EPA and DHA. In recent years, the separate effects of EPA and DHA on the risk factors of CVD have been shown in order to have a better understanding of their mechanisms. Asztalos et al. [60] recruited 121 healthy, normolipidemic subjects, where subjects were randomly assigned into four treatment groups: two doses of EPA (1800 and 600 mg/day), one dose of DHA (600 mg/day), and olive oil without EPA and DHA (control). After 6 weeks of intervention, the DHA group showed a significant decrease in the postprandial TG concentration compared with the control group although the fasting TG remained unchanged. However, interestingly, the DHA group also displays a significant increase in the low-density lipoprotein cholesterol (LDL) level. Although the EPA groups did not show the same results, there was a significant decrease in the lipoproteinassociated phospholipase A2 concentration, which is an inflammatory marker, at the dose of 1800 mg EPA/day. It seems that both EPA and DHA can decrease the CVD risk factors, and DHA may be more effective in reducing the lipid risk factors than EPA [61].

#### **9. Cancers**

Cancer is one of the most frequently diagnosed diseases worldwide, cancer is one of the leading causes of death in the Western world, and omega-3 fatty acids have long been claimed to reduce the risk of certain cancers. Interestingly, studies indicate that people who take the most omega-3s have up to a 55% lower risk of colon cancer [62, 63]. Additionally, omega-3 consumption is linked to a reduced risk of prostate cancer in men and breast cancer in women. However, not all studies show the same results [64–66].

#### **10. Vision and eye health**

Age-related macular degeneration is a major cause of blindness worldwide. With aging populations in many countries, more than 20% might have the disorder. DHA, a type of omega-3, is a key structural component of the retina of your eye [67]. When enough DHA is not present in the body, vision problems may arise [68, 69]. Interestingly having enough omega-3 is linked to a reduced risk of macular degeneration, one of the world's leading causes of permanent eye damage and blindness [69, 70].

#### **11. Inflammatory bowel disease**

The anti-inflammatory effects of omega-3 fats may assist in managing inflammatory bowel disease (IBD) and other gastrointestinal diseases causing inflammation, but the available evidence is weak [71, 72]. In one study, 4.2 g of fish oil daily for 8 months reduced the symptoms of active mild-to-moderate ulcerative colitis [73]. However, a review of three clinical trials and 138 ulcerative colitis patients found no significant benefits of fish oil supplementation**.** The authors suggested further trials with improved fish oil formulation (enteric-coated capsules) [74].

#### **12. Depression and anxiety**

Symptoms of depression include sadness, lethargy, and a general loss of interest in life [75]. Anxiety is also a common disorder and is characterized by constant worry and nervousness [76]. It is one of the most common mental disorders in the world. Interestingly, studies indicate that people who eat omega-3 s regularly are less likely to be depressed [77, 78]. What's more, when people with depression or anxiety start consuming omega-3 supplements, their symptoms improve [79, 80]. ALA, EPA, and DHA are the three types of omega-3 fatty acids. Of the three, EPA seems to be the best at fighting depression [81].

#### **13. Improving ADHD**

Attention deficit hyperactivity disorder (ADHD)—characterized by impulsive behaviors and difficulty concentrating—generally starts in childhood but often continues into adulthood [82]. As the main omega-3 fat in your brain, DHA helps boost blood flow during mental tasks. Research has demonstrated that children and adults with ADHD commonly have lower blood levels of DHA [82–84]. In a recent review, seven of nine studies that tested the effects of DHA supplements in children with ADHD give some improvement—such as with regard to attention or behavior [85]. For example, in a large 16-week study in 362 children, those taking 600 mg of DHA daily had an 8% decrease in impulsive behaviors as rated by their parents, which was twice the decrease observed in the placebo group [86]. In another 16-week study in 40 boys with ADHD, 650 mg each of DHA and EPA daily alongside the children's usual ADHD medication resulted in a 15% decrease in attention problems [87].

#### **14. Metabolic syndrome**

A metabolic syndrome is a group of conditions. It consists of central obesity also known as belly fat—as well as high blood pressure, insulin resistance, high

triglycerides, and low "good" HDL cholesterol levels. It is a major public health issue because it increases your risk of many other illnesses, including heart disease and diabetes [88]. Omega-3 fatty acids can help insulin resistance, inflammation, and heart disease risk factors in people with metabolic syndrome [80, 89, 90].

#### **15. Skin health**

DHA is a structural component of our skin. It is responsible for the health of cell membranes, which are up to a large part of your skin. A healthy cell membrane shows soft, moist, supple, and wrinkle-free skin. EPA also benefits the skin in several ways, including managing oil production, and skin hydration, and preventing hyperkeratinization of hair follicles, which appears as the little red bumps often seen on upper arms, reducing premature aging of your skin, reducing the risk of acne [91, 92]. Omega-3s can also save your skin from sun damage. EPA aids in blocking the release of substances that eat away at the collagen in your skin after sun exposure [91, 93].

#### **16. Early preterm births**

Delivering a baby before 34 weeks of pregnancy is known as early preterm birth and increases the baby's risk of health problems [94, 95]. An analysis of two large studies shows that women consuming 600–800 mg of DHA daily during pregnancy decreased their risk of early preterm birth by more than 40% in the US and 64% in Australia, compared to those taking a placebo [96]. Therefore, it is especially critical to make sure that you are getting sufficient amounts of DHA when you are pregnant—either through diet, supplements or both.

#### **17. Age-related cognitive decline (ARCD) and Alzheimer's disease**

Docosahexaenoic acid (DHA) has an important role in neural function. Decreases in plasma DHA are related to cognitive decline in healthy elderly adults and in patients with Alzheimer's disease. A higher DHA level is inversely correlated with a relative risk of Alzheimer's disease. Twenty-four-week supplementation with 900 mg/d DHA is reported to improve learning and memory function in ARCD and is a beneficial supplement that supports cognitive health with aging [97].

#### **18. Kidney disorders**

Researchers at the Mayo Clinic report that patients with IgA nephropathy have an abnormal EFA profile and that this abnormality can be corrected by supplementation with fish oil. The researchers conclude that fish oil supplementation retards the progression of IgA nephropathy [98]. Kidney transplant patients also benefit from fish oils [99].

#### **19. Neuropathic pain**

Pain is an electrical signal interpreted by one's brain. Neuropathic pain or nerve pain is a chronic pain state that usually (but not always) is caused by some sort of tissue trauma. In neuropathic pain, the nerve fibers themselves get often damaged, dysfunctional, or injured. These damaged nerve fibers transmit incorrect electrical signals to the brain's pain centers. The first-ever reported case series suggests that omega-3 fatty acids may be of benefit in the management of patients with neuropathic pain [100]. Longchain omega-3 fatty acids supplementation accelerates nerve regeneration and prevents neuropathic pain behavior in mice [101]. Treatment with omega-3 PUFA could represent a promising therapeutic approach in the management of neurological injury [102].

#### **20. Benefits for the aging brain**

Brain volume shrinks with age [103], with a parallel decrease in DHA composition [104]. DHA is critical for healthy brain aging. With aging, your brain goes through natural changes, characterized by increased oxidative stress, altered energy metabolism, and DNA damage [105], while many of these changes are also seen when DHA levels decrease. These include altered membrane properties, enzyme activity, memory function, and neuron function [106]. Importantly, n-3 PUFA intake is positively correlated with gray matter volume in adults [107] and in brain regions responsible for cognition in normal, elderly adults [108]. Taking a supplement may help, as DHA supplements have been linked to significant improvements in memory, learning, and verbal fluency in those with mild memory complaints [108]. Environmental factors, such as diet, exercise, and DHA consumption, can positively affect the normal aging process and overall mental health and performance [109].

#### **21. Benefits of asthma in children**

Asthma is a chronic lung disease, which has symptoms like coughing, shortness of breath, and wheezing. Severe asthma attacks can have very dangerous attacks. They are characterized by inflammation and swelling in the airways of your lungs. Specialized pro-resolving mediators (SPM: protectins, resolvins, and maresins) are released from omega-3 fatty acids, such as EPA and DHA, *via* several enzymatic reactions. These mediators counter-regulate airway eosinophilic inflammation and promote the resolution of inflammation *in vivo* [110, 111]. Several studies link omega-3 consumption with a lower risk of asthma in children and young adults [112, 113].

#### **22. Fat reduction in liver**

Nonalcoholic fatty liver disease (NAFLD) is more common than you think. It has increased with the obesity epidemic to become the most common cause of chronic liver disease in the Western world [114]. However, supplementing with omega-3 fatty acids effectively decreases liver fat and inflammation in people with NAFLD [115].

#### **23. Psychosis**

In a study of 81 young patients with mild psychosis, low-dose omega-3 supplementation (1.2 g/day) significantly reduced the incidence of psychotic disorders [94]. Further trials should investigate this potential benefit of omega-3/fish oil.

*DHA (Docosahexaenoic Acid): A Biomolecule with Diverse Roles and Health Benefits DOI: http://dx.doi.org/10.5772/intechopen.109677*

#### **24. Cachexia**

Taking mega-doses (7.5–8.1 g daily) of fish oil slightly slowed down weight loss in 67 patients with cancer-related cachexia (severe weakness and wasting) [116, 117]. Lower doses (3 g daily) do not seem to have beneficial effects [118].

#### **25. Aggression**

DHA significantly reduced aggression due to mental stress in a study of 41 students. The same group of authors failed to confirm this benefit in non-stressful situations [119, 120]. In a 6-month study on 200 school children aged 8–16 years old, omega-3 supplementation caused a significant reduction in several measures of aggression [121].

#### **26. Rheumatoid arthritis**

Resolvins found in EPA and DHA appear to prevent certain inflammatory cytokines, such as TNF-α from inducing pain [122]. Long-term supplementation with fish oils benefits rheumatoid arthritis patients significantly and may lessen their need for NSAIDs and other RA medications [123]. Dietary fish oil supplements should now be regarded as part of standard therapy for rheumatoid arthritis [124, 125].

#### **27. Osteoporosis and bone health**

Osteoporosis and arthritis are two common disorders that affect your skeletal system. Studies show that omega-3 s can improve bone strength by boosting the amount of calcium in your bones, which should lead to a reduced risk of osteoporosis [126, 127]. Omega-3 s may also cure arthritis. Patients taking omega-3 supplements have been reported to have reduced joint pain and increased grip strength [128, 129].

#### **28. Omega-3s and menstrual pain**

Menstrual pain occurs in your lower abdomen and pelvis and often radiates to your lower back and thighs. It can significantly affect the quality of female life. However, studies repeatedly prove that women who consume the most omega-3s have milder menstrual pain [129, 130]. One study even determined that an omega-3 supplement was more effective than ibuprofen in treating severe pain during menstruation [131].

#### **29. Good sleep**

Good sleep is one foundation for good health. Low levels of omega-3 fatty acids are associated with sleep problems in children and obstructive sleep apnea in adults [131, 132]. Low levels of DHA are also linked to lower levels of the hormone melatonin,

which helps you fall asleep [133]. Studies in both children and adults reveal that supplementing with omega-3 increases the length and quality of sleep [132, 133].

#### **30. Blood pressure reduction and circulation help**

DHA boosts good blood flow, or circulation, and may help endothelial function the ability of your blood vessels to dilate [134]. A review of 20 studies found that DHA and EPA may also help in lowering blood pressure, though each specific fat may affect different aspects. DHA decreases diastolic blood pressure (the bottom number of a reading) by an average of 3.1 mmHg, while EPA helps lower systolic blood pressure (the top number of a reading) by an average of 3.8 mmHg [135].

#### **31. DHA in sport nutrition**

DHA may influence sports performance by improving aerobic processes and using fat as an energy substrate [136]. The applications of omega-3 supplementation for sports performance seem to be relevant for athletes involved in strength, endurance, and team-based activities. However, determining exactly how they work and how much omega-3s may benefit strength, endurance, and recovery is not confirmed. This is accomplished by enhancing the delivery of oxygen and nutrients and removing waste products from tissues. Postexercise recovery time may decrease due to reduced inflammation and increased release of growth hormones [137].

Walser et al. [137], reported that stroke volume and cardiac output increased during exercise when DHA + EPA were administered to subjects. This finding suggests that DHA + EPA may increase oxygen delivery during exercise [138]. Other researchers have shown that DHA + EPA supplementation improves circulatory function through. DHA supplementation improves minute heart rate recovery after exercise. Both of these DHA-related effects may contribute to better athletic performance and exercise recovery. DHA supplementation during exercise positively affects cognition and the strength of the connection between synapses in the brain [139].

#### **32. DHA and skeletal muscle**

Skeletal muscle disuse results in a reduction in fed and fasted rates of skeletal muscle protein synthesis, leading to the loss of skeletal muscle mass. Recent evidence has shown that supplementation with ω-3 fatty acids during a period of skeletal muscle disuse increases the ω-3 fatty acid composition of skeletal muscle membranes, heightens rates of skeletal muscle protein synthesis, and protects against skeletal muscle loss. Omega-3 fatty acid ingestion is a potential preventive therapy to combat skeletal muscle-disuse atrophy but additional, appropriately powered randomized controlled trials are now needed in a range of populations before firm conclusions can be made [140]. Following n3-PUFA supplementation, mixed muscle, mitochondrial, and sarcoplasmic protein synthesis rates were moved up higher in older adults before exercise. n3-PUFA boosts postexercise mitochondrial and myofibrillar protein synthesis in older adults. These results have shown that n3-PUFA reduces mitochondrial oxidant emissions, increases postabsorptive muscle protein synthesis, and enhances anabolic responses to exercise in older adults [141]. Enrichment of EPA and DHA in

these membrane phospholipids is linked to enhanced rates of muscle protein synthesis, decreased expression of factors that regulate muscle protein breakdown, and improved mitochondrial respiration kinetics [141].

#### **33. Men's reproductive and sexual health**

As wellness professionals would agree, fish oil does help with sexual performance and more. They would recommend filling up with the omega-3 in fish oil every day to be empowered sexually with maximum energy and drive. Neurons, photoreceptor cells, and spermatozoa are three cell types that show high DHA content. The structural integrity of the spermatozoa cell membrane plays a pivotal role in successful fertilization. This is because both the acrosome reaction and sperm-oocyte fusion is associated with the membrane's fatty acid profile [142].

The majority of researchers have demonstrated that DHA (22:6n-3) is a major PUFA in human spermatozoa. Its deficiency is a typical sign in spermatozoa of subfertile or infertile men [143]. DHA comprises up to 30% of esterified fatty acids in phospholipids and 73% of all PUFAs and it gives proper fluidity to fertile sperm [142]. The percentage of DHA in sperm membrane phospholipids was higher than that of DHA in other cells. Hence, PUFA metabolism was more active in the testes during spermatogenesis and epididymal sperm maturation than these PUFA metabolism in other cells [144]. Interestingly, Zalata et al. have indicated that DHA in human spermatozoa may have specific functions unrelated to fluidity, which is similar to the functions of DHA in the brain and retina. More recently, it has been suggested that lipid concentrations may affect semen parameters, and this effect is more pronounced in sperm head morphology [145] Inadequate DHA concentration is the main cause of low-quality spermatozoa. Getting adequate DHA supports both the vitality and motility of sperm and improves sperm quality and function, which impacts fertility [142].

For erectile dysfunction**,** consuming a fish oil concentrate improves blood flow to the pelvis, reduces inflammation, and cuts the risk of tiny blood clots that impede erections. Highly absorbable omega-3 fats in a concentrate also stabilize hormone and neurotransmitter balance, for stronger erections that are sustained longer [146]. A healthy heart is a good sign of a functioning penis.

"Many of our male patients over the years are receiving enduring improvements in erectile dysfunction, taking a potent fish oil concentrate for at least 6 months."—Dr. Rachelle Herdman.

#### **34. Benefits for healthy hair growth**

Fatty acids promote hair growth, as well as add sheen and luster to hair. A proper amount of omega-3 in your diet prevents dry, itchy, flaky scalp, and is beneficial in reversing hair loss [147].

#### **35. Help in stem cells**

Omega-3 fatty acids support stem cells [148]. The available evidence shows that n-6 and n-3 PUFA and their metabolites can act through multiple mechanisms to promote the proliferation and differentiation of various stem cell types [149].

#### **36. Conclusion**

In summary, the health benefits of DHA start from the baby's formation in the mother's womb and continue to the adolescent and adult stages up to aging for men and women, including sexual health. Higher DHA levels in body are associated with better mental, physical health, and performance enhancement while low level of DHA has been linked to physical and mental diseases that may cost huge financial burdens. So, DHA is a critical component for a happy life. There have been negative results in a few human trials of the effectiveness of omega-3 fatty acids starting from even CVD. However, the substantial literature of positive results outweighs the negative results. It will be wiser for us to keep the optimum level of DHA in our bodies throughout life. Indeed, it needs more research to verify them more.

#### **Acknowledgements**

Authors acknowledge gratefully the initiation of IntechOpen .com team for the book and the typist for his help.

#### **Author details**

Abdul Hei\* and Laishram Sanahanbi Lilong Haoreibi College, Lilong, Manipur, India

\*Address all correspondence to: ahei541@gmail.com

© 2023 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*DHA (Docosahexaenoic Acid): A Biomolecule with Diverse Roles and Health Benefits DOI: http://dx.doi.org/10.5772/intechopen.109677*

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