Dietary Sources of Carotenoids and Their Bioavailability

#### **Chapter 5**

## Carotenoids: Sources, Bioavailability and Their Role in Human Nutrition

*Indu Sharma, Neeraj Khare and Archana Rai*

#### **Abstract**

Carotenoids are a group of pigments that are widely distributed in the plant kingdom. They are important dietary components with potential health benefits, including antioxidant and anti-inflammatory properties and have been linked to the prevention of chronic diseases such as cancer, cardiovascular disease, and age-related degeneration. It provides a global perspective on the role of carotenoids in human nutrition and health, including their sources, bioavailability, metabolism, and physiological effects. Carotenoids are a group of compounds, including beta-carotene, lycopene, lutein, zeaxanthin, and others, that differ in their chemical structures and biological activities. They are found in a wide range of foods, including fruits, vegetables, grains, and animal products, and their bioavailability is influenced by a variety of factors. It explains the challenges and opportunities for increasing carotenoid consumption through dietary interventions and supplementation. However, the efficacy of these interventions depends on a variety of factors, including cultural norms, food availability and consumer preferences. Overall, this chapter provides a comprehensive overview of carotenoids and their role in human nutrition and health, highlighting the importance of these compounds for disease prevention and management. It also underscores the need for continued research to further understand the mechanisms by which carotenoids exert their health benefits, and to develop effective strategies for increasing their consumption in populations around the world.

**Keywords:** carotenoids, bioactive compounds, sources, chronic diseases, phytonutrients, human health

#### **1. Introduction**

Carotenoids are a diverse group of natural pigments that play essential roles in the vibrant colors of fruits, vegetables and various organisms in the natural world. These organic compounds are synthesized by plants, algae, fungi and some bacteria, these are responsible for the yellow, orange and red hues seen in many of these organisms [1].

Carotenoids not only contribute to the visual appeal of these colorful entities but also serve crucial functions in their growth, development and overall health. With over 700 known carotenoids identified to date, these pigments display remarkable

structural diversity. They consist of isoprene units linked together to form a long hydrocarbon chain, often with conjugated double bonds. This conjugation gives rise to their characteristic color and also makes them efficient in absorbing light energy.

They serve as antioxidants, protecting cells from damage caused by harmful free radicals. Carotenoids are also involved in light-harvesting and photoprotection in photosynthetic organisms, playing a crucial role in capturing and transferring light energy during photosynthesis. In plants, carotenoids are essential for photosynthesis and photoprotection [2].

The biological activities and health benefits associated with carotenoids have garnered significant interest from researchers and health professionals alike. Furthermore, carotenoids are important precursors for the synthesis of vitamin A, a vital nutrient for human health that is essential for vision, immune function and cell growth. Studies have suggested that carotenoids may have protective effects against chronic diseases such as cancer, cardiovascular diseases, and age-related macular degeneration. Their potential as dietary supplements and nutraceuticals has also gained attention in recent years.

This book chapter aims to explore the fascinating world of carotenoids, delving into their diverse structures, functions, sources and potential health benefits. By examining the latest scientific research and understanding their roles in nature and human health, we can gain a deeper appreciation for the significance of these remarkable pigments. Carotenoids are a diverse group of natural pigments that are widely distributed in nature and have captivated scientists, nutritionists and food enthusiasts alike. From the vivid red of ripe tomatoes to the vibrant orange of carrots and the golden yellow of sunflowers, carotenoids are responsible for the striking colors we often associate with fruits, vegetables, and flowers. However, their significance extends far beyond mere esthetics.

Chemically, carotenoids are tetraterpenoids, meaning they are composed of long chains of isoprene units. The presence of conjugated double bonds along these chains gives carotenoids their characteristic color and makes them highly efficient at absorbing light energy across a broad range of wavelengths. In fact, carotenoids are among nature's most efficient light-harvesting pigments, allowing plants and photosynthetic organisms to harness energy from sunlight for photosynthesis [2].

Beyond their role in photosynthesis, carotenoids serve as vital components of the biological machinery in various organisms. In plants, they act as antioxidants, protecting cells from oxidative damage caused by harmful free radicals generated during metabolic processes or in response to environmental stresses. Carotenoids also play a role in signaling and communication between cells, influencing processes such as development, reproduction, and defense against pathogens [3, 4].

Humans and animals cannot synthesize carotenoids and must obtain them through their diet. Once ingested, these pigments serve multiple functions within the body. Some carotenoids, like beta-carotene, can be converted into vitamin A, an essential nutrient that is crucial for vision, growth, immune function and maintaining healthy skin. Other carotenoids, such as lycopene and lutein, exhibit potent antioxidant properties and have been linked to a range of health benefits, including reducing the risk of chronic diseases like cancer, cardiovascular diseases, and agerelated macular degeneration [5].

Given their importance, carotenoids have attracted considerable scientific interest. Researchers have focused on understanding their biosynthesis, chemical properties and physiological roles, as well as exploring their potential applications in areas such

as medicine, nutrition, and cosmetics. Moreover, the discovery of new carotenoids with unique properties and functions continues to expand our knowledge and opens up possibilities for novel applications.

This chapter will provide a comprehensive overview of carotenoids, exploring their chemical structures, sources in nature, functions, and the latest research on their potential health benefits. By delving into the captivating world of carotenoids, we can gain a deeper appreciation for these pigments and their multifaceted roles in the natural world and human well-being.

#### **2. Carotenoids**

Their definition, chemistry, types, dietary sources, properties and mechanisms of action.

#### **2.1 Definition of carotenoids**

Carotenoids are a class of pigments found in plants, algae and some microorganisms. They are responsible for the vibrant colors seen in various fruits, vegetables and flowers. Chemically, carotenoids are tetraterpenoid compounds composed of carbon and hydrogen atoms, with some also containing oxygen. They are categorized into two main groups: carotenes, which are hydrocarbons and xanthophylls, which contain oxygen atoms [6].

#### **2.2 Chemistry of carotenoids**

Carotenoids are a group of pigments, mostly of plant origin, responsible for the yellow, orange and red colors in fruits and vegetables. All have antioxidant activity, and some are precursors of vitamin A. Additionally, carotenoids have a role in intercellular communication, immune system activation and disease prevention and promote human health [7, 8].

Carotenoids belong to the category of tetraterpenoids (i.e. they contain 40 carbon atoms, being built from four terpene units each containing 10 carbon atoms). Structurally, carotenoids take the form of a polyene hydrocarbon chain which is sometimes terminated by rings, and may or may not have additional oxygen atoms attached.

Carotenoids comprise eight repetitive units of isoprene, with cyclic or linear structures at both ends of the carbon chains, resulting in multiple cis and trans isomers, with the latter being more abundant in nature [9, 10]. Carotenoids are a class of natural compounds composed of isoprene units, with their structures characterized by a long polyene chain containing conjugated double bonds. The presence and arrangement of these double bonds determine the color and properties of individual carotenoids. Beta-carotene, for example, has a chain of 11 conjugated double bonds, while lycopene has 13 conjugated double bonds.

Carotenoids are classified into carotenes and xanthophylls. Carotenes, such as α-carotene, β-carotene, γ-carotene and lycopene, are highly soluble in organic solvents and insoluble in polar solvents. In contrast, xanthophylls are soluble in polar solvents (e.g., alcohols) and organic solvents (e.g., ether and hexane). They are oxygenated derivatives of carotenes, forming alcohols, aldehydes, ketones and

#### **Figure 1.**

*Structure of the most common natural carotenoids [11].*

acids. Examples of xanthophylls are fucoxanthin, lutein and violaxanthin [9, 10] (**Figure 1**).

**Figure 1** shows the chemical structures of several carotenes and xanthophylls. Carotenoids are stored in plant tissues (plastids), such as chromoplasts (colored plastids), amyloplasts (starch storage plastids) and elaioplasts (lipid storage plastids). *Carotenoids: Sources, Bioavailability and Their Role in Human Nutrition DOI: http://dx.doi.org/10.5772/intechopen.113012*

In fruits, flowers and roots, carotenoids are located in the chromoplast, whereas in grains and oilseeds they are located in amyloplasts and elaioplasts, respectively [11, 12]. Xanthophylls are freely found in green plant tissues, whereas in fruits and flowers they are found as esters of fatty acids [13].

The biosynthesis of carotenoids takes place in the chloroplasts. Two molecules of geranylgeranyl diphosphate (GGPP) are produced from isopentenyl pyrophosphate (IPP) and dimethylallyl diphosphate (DMAPP), catalyzed by geranylgeranyl pyrophosphate synthase (GGPS). After this, two molecules of GGPP are condensed into phytoene by phytoene synthase (PSY). Subsequently, phytoene is desaturated into lycopene by ε carotene desaturase (ZDS) and phytoene desaturase (PDS). Lycopene is cyclized into α-carotene (α pathway) and β-carotene (β pathway), in reactions catalyzed by lycopene-ε (LYC-ε) and β-cyclase (LYC-β), respectively. Xanthophylls are synthesized from carotenes; lutein is formed by the action α-carotene ring-ε hydroxylase (CHY-ε) via the α pathway; β-carotene is converted into β-cryptoxanthin via the β pathway, in a reaction catalyzed by β-carotene hydroxylase (CHY-β), which also catalyzes its conversion into zeaxanthin. In turn, zeaxanthin can be converted into violaxanthin by zeaxanthin epoxidase (ZEP); conversely, violaxanthin can be converted into zeaxanthin by violaxanthin deepoxidase (VDE). Finally, violaxanthin is converted into neoxanthin by neoxanthin synthase (NXS) [14] (**Figure 2**).

#### **2.3 Types of carotenoids**

Carotenoids are a group of pigments and food micronutrients widely distributed in nature that play essential roles in various biological processes. They are responsible for the vibrant colors seen in fruits, vegetables and flowers. Carotenoids are not only visually appealing but also possess significant health benefits, as many of them act as antioxidants and are associated with reduced risks of chronic diseases. This article aims to explore the classification and types of carotenoids found in nature.

Carotenoids can be classified into two main groups based on their chemical structure: carotenes and xanthophylls. Carotenes are hydrocarbons, while xanthophylls are oxygenated derivatives of carotenes (**Figures 1** and **3**).

Carotenoids are organic compounds synthesized by plants, algae and some bacteria. They can be divided into two primary categories: carotenes and xanthophylls. Carotenes, such as beta-carotene, lycopene and alpha-carotene, provide red, orange and yellow hues. Xanthophylls, including lutein, zeaxanthin and astaxanthin, contribute to yellow, orange, and red colors in foods. Each carotenoid has unique properties and potential health benefits [15].

#### *2.3.1 Carotenes*

Carotenes are the simplest form of carotenoids and are composed of carbon and hydrogen atoms only. They are insoluble in water but soluble in lipids, making them ideal for their function in photosynthetic systems. Some common carotenes include: β-carotene, β-cryptoxanthin, α-carotene, lycopene, lutein and zeaxanthin [16, 17].

*Alpha-carotene*: Alpha-carotene is commonly found in carrots, pumpkin, and winter squash. It has antioxidant properties and is converted to vitamin A in the body. Studies suggest that higher intake of alpha-carotene is associated with a reduced risk of various chronic diseases.

#### **Figure 2.**

*Carotenoid biosynthesis pathway in plants. Geranyl-geranyl pyrophosphate synthase (GGPS), phytoene synthase (PSY), ζ-carotene desaturase (ZDS), phytoene desaturase (PDS), lycopene ε-cyclase (LYC-ε), lycopene β-cyclase (LYC-β), α-carotene ring-ε hydroxylase (CHY-ε), β-carotene hydroxylase (CHY-β), zeaxanthin epoxidase (ZEP), violaxanthin de-epoxidase (VDE), and neoxanthin synthase (NXS) [14].*

*Beta-carotene*: Beta-carotene is the most well-known carotene and is abundant in fruits and vegetables such as carrots, sweet potatoes, and spinach. It is a provitamin A compound, meaning it can be converted into vitamin A in the body, which is crucial for vision, immune function, and cell growth.

*Lycopene*: Lycopene is a red pigment found in tomatoes, watermelon, and pink grapefruit. It is a potent antioxidant and has been associated with a reduced risk of certain cancers, particularly prostate cancer.

*Carotenoids: Sources, Bioavailability and Their Role in Human Nutrition DOI: http://dx.doi.org/10.5772/intechopen.113012*

**Figure 3.**

*Carotenoids sources, bioavailability and their role in human nutrition.*

#### *2.3.2 Xanthophylls*

Xanthophylls are carotenoids that contain oxygen in addition to carbon and hydrogen. They are typically yellow or orange pigments. Some prominent xanthophylls include:

*Lutein*: Lutein is present in high amounts in leafy green vegetables such as kale, spinach, and broccoli. It is known for its role in promoting healthy vision and reducing the risk of age-related macular degeneration (AMD), a leading cause of blindness in older adults.

*Zeaxanthin*: Zeaxanthin is another important carotenoid found in green leafy vegetables and brightly colored fruits. It is concentrated in the retina of the eye and works together with lutein to protect against AMD and promote optimal vision.

*Astaxanthin*: Astaxanthin is a red pigment found in seafood, particularly in salmon, shrimp, and lobster. It is a potent antioxidant and has been associated with numerous health benefits, including reducing inflammation, enhancing skin health, and supporting heart health.

*Cryptoxanthin*: Cryptoxanthin is found in oranges, peaches, and papayas. It can be converted to vitamin A in the body and has antioxidant properties. Research suggests that cryptoxanthin intake may be associated with a reduced risk of lung and cervical cancers.

These are just a few examples of carotenoids among the hundreds identified in nature. Each carotenoid offers unique health benefits and contributes to the vibrant colors we see in fruits and vegetables.

Beta-carotene, lycopene, lutein, zeaxanthin, and other carotenoids are a diverse group of pigments widely found in nature. These compounds are responsible for the vibrant colors seen in various fruits, vegetables and plants. Carotenoids play crucial roles in both the plant kingdom and the animal kingdom, offering numerous health benefits and protecting against certain diseases. In this article, we will explore the chemical structures, biological activities, and dietary sources of these important carotenoids.

These carotenoids serve as antioxidants in the body, protecting cells and tissues from damage caused by harmful free radicals. These compounds have been linked to a variety of health benefits, including a reduced risk of chronic diseases such as cancer, cardiovascular disease, and age-related macular degeneration.

Beta-carotene, in particular, is a precursor to vitamin A and plays a crucial role in vision, immune function, and cellular growth. It is found in abundance in orangecolored fruits and vegetables such as carrots, sweet potatoes, and apricots.

Lycopene is a red pigment primarily found in tomatoes and watermelons. It is known for its potent antioxidant properties and has been associated with a lower risk of prostate cancer. Lycopene's ability to quench singlet oxygen, a highly reactive form of oxygen, contributes to its protective effects against oxidative stress.

Lutein and zeaxanthin are two carotenoids that are heavily concentrated in the macula of the eye. They play a critical role in maintaining healthy vision and reducing the risk of age-related macular degeneration, a leading cause of blindness in older adults. Leafy green vegetables such as spinach and kale are excellent dietary sources of lutein and zeaxanthin [18].

Aside from these well-known carotenoids, there are numerous other carotenoids with unique structures and biological activities. For example, astaxanthin, found in microalgae, salmon, and shrimp, is a powerful antioxidant known for its anti-inflammatory properties. It has been studied for its potential benefits in cardiovascular health and exercise performance.

Another notable carotenoid is lycopene-β-cyclase, which can be converted to betacryptoxanthin, a carotenoid that may have anti-inflammatory and immune-boosting effects. Beta-cryptoxanthin is found in citrus fruits, such as oranges and tangerines, as well as in papaya and mango.

Incorporating a wide variety of carotenoids into our diets is essential to reap their health benefits. Consuming a diverse range of colorful fruits and vegetables ensures a good intake of these important compounds. It is important to note that the absorption and utilization of carotenoids can be enhanced by consuming them with dietary fats. For instance, adding a healthy fat source, such as olive oil, avocado, or nuts, to a salad containing lutein and zeaxanthin-rich vegetables can optimize their absorption by the body.

Beta-carotene, lycopene, lutein, zeaxanthin, and other carotenoids are valuable compounds with diverse chemical structures and biological activities. These pigments contribute to the vibrant colors of fruits and vegetables and offer numerous health benefits, including antioxidant protection and disease prevention. By incorporating a variety of carotenoids into our diets, we can promote optimal health and well-being. Here are some additional carotenoids and their dietary sources:

*Carotenoids: Sources, Bioavailability and Their Role in Human Nutrition DOI: http://dx.doi.org/10.5772/intechopen.113012*

*Alpha-carotene*: This carotenoid is closely related to beta-carotene and shares similar health benefits. It is found in carrots, pumpkins, winter squash, and green leafy vegetables like spinach and kale.

*Cryptoxanthin*: It is a provitamin A carotenoid that can be converted into vitamin A in the body. Good dietary sources include citrus fruits such as oranges, tangerines, and grapefruits, as well as papaya, peaches, and mangoes.

*Canthaxanthin*: It is a red-orange pigment found in crustaceans like shrimp, lobster, and crab. It is also used as a food coloring agent.

*Zeinoxanthin*: This carotenoid is present in sweetcorn, oranges, and orange peppers. It has been studied for its potential protective effects against ultraviolet (UV) radiation.

*Antheraxanthin*: It is a carotenoid found in green leafy vegetables, green peppers, and parsley.

*Violaxanthin*: It is found in yellow and green vegetables, as well as in flowers like pansies and violas.

*Neoxanthin*: This carotenoid is abundant in green leafy vegetables, broccoli, peas, and green beans.

Each carotenoid offers unique benefits to human health. For instance, some carotenoids possess anti-inflammatory properties, while others may support cardiovascular health or boost the immune system. These compounds also act as natural photoprotectants, shielding the skin from UV-induced damage and reducing the risk of sunburn.

In addition to their health benefits, carotenoids contribute to the visual appeal of food, making meals more enticing and enjoyable. Incorporating a colorful assortment of fruits and vegetables into our diets not only ensures an array of carotenoids but also provides a wide range of essential vitamins, minerals, and fiber.

While carotenoids are predominantly found in plant-based foods, it is worth noting that the bioavailability of these compounds can vary. Factors such as food processing, cooking methods, and the presence of dietary fats can influence their absorption and utilization by the body. To maximize the benefits, it is advisable to consume a combination of raw and cooked vegetables, and to include healthy fats when appropriate.

In conclusion, carotenoids such as beta-carotene, lycopene, lutein, zeaxanthin, and their lesser-known counterparts, offer a multitude of health benefits and are abundant in various fruits, vegetables, and other natural sources. By incorporating a diverse range of colorful plant-based foods into our diets, we can ensure a rich intake of these valuable compounds and support our overall health and well-being.

#### *2.3.3 Some additional types of carotenoids*

*Canthaxanthin*: Canthaxanthin is a carotenoid found in mushrooms, crustaceans, and fish. It is used as a food coloring agent and is also commonly used as a pigment in cosmetics. Canthaxanthin has antioxidant properties and has been studied for its potential role in eye health.

*Beta-cryptoxanthin*: Beta-cryptoxanthin is found in citrus fruits such as oranges, tangerines, and mandarins. It is a provitamin A carotenoid and is converted to vitamin A in the body. Beta-cryptoxanthin has been associated with a reduced risk of inflammatory conditions such as rheumatoid arthritis.

*Fucoxanthin*: Fucoxanthin is a carotenoid predominantly found in brown seaweed, such as kombu and wakame. It is responsible for the brown color of these seaweeds. Fucoxanthin has gained attention for its potential anti-obesity effects, as it has been shown to promote fat burning and inhibit fat cell formation in animal studies.

*Zeinoxanthin*: Zeinoxanthin is a carotenoid found in corn, leafy greens, and egg yolks. It is closely related to zeaxanthin and has similar antioxidant properties. Zeinoxanthin may contribute to eye health and protect against oxidative stress.

*Neoxanthin*: Neoxanthin is found in green leafy vegetables, algae, and some fruits. It is involved in light-harvesting processes in plants and is essential for photosynthesis. Neoxanthin has antioxidant activity and may contribute to the overall health benefits of plant-based diets.

*Violaxanthin*: Violaxanthin is a carotenoid found in yellow and orange fruits such as oranges, apricots, and peaches. It plays a role in protecting plants from excess light and oxidative stress. Violaxanthin may also possess anti-inflammatory properties and contribute to the health benefits of consuming fruits.

*Rubixanthin*: Rubixanthin is a carotenoid found in red and purple fruits and vegetables, including raspberries, cranberries, and purple sweet potatoes. It is responsible for their vibrant red and purple hues. Rubixanthin exhibits antioxidant properties and may have potential health benefits.

It's important to note that carotenoids are not produced by the human body, so it's crucial to obtain them through varied and balanced diet rich in fruits, vegetables, and other plant-based foods. By incorporating a wide range of carotenoid-rich foods into your meals, you can reap the benefits of these natural pigments and support your overall health and well-being (**Figure 3**).

#### **2.4 Properties of carotenoids**

*Antioxidant properties*: Carotenoids act as powerful antioxidants, helping to protect cells and tissues from oxidative damage caused by harmful free radicals. This oxidative stress can lead to various chronic diseases, including cardiovascular disorders and certain types of cancer. Carotenoids help neutralize these free radicals, reducing the risk of cellular damage.

*Antioxidant power*: Carotenoids act as powerful antioxidants in the body, helping to protect cells from damage caused by harmful free radicals. Free radicals are unstable molecules that can lead to oxidative stress, which is associated with various chronic diseases, including heart disease, cancer, and neurodegenerative disorders. By neutralizing free radicals, carotenoids help maintain cellular health and reduce the risk of oxidative damage.

*Provitamin A activity*: Certain carotenoids, such as beta-carotene, can be converted into vitamin A within the body. Vitamin A is essential for maintaining healthy skin, promoting proper immune function, and supporting good vision. Carotenoids serve as a valuable dietary source of vitamin A, particularly in individuals with limited access to animal-based foods.

*Anti-inflammatory properties*: Some carotenoids exhibit anti-inflammatory properties by inhibiting the production of pro-inflammatory molecules in the body. Chronic inflammation is linked to numerous health conditions, including cardiovascular diseases, diabetes, and certain cancers. By reducing inflammation, carotenoids may help lower the risk of these inflammatory diseases.

#### *Carotenoids: Sources, Bioavailability and Their Role in Human Nutrition DOI: http://dx.doi.org/10.5772/intechopen.113012*

*Immune function*: Carotenoids have been shown to have immunomodulatory effects, meaning they can regulate immune responses. They help enhance the activity of immune cells, such as lymphocytes and natural killer cells, which are crucial for fighting off infections and diseases. By supporting a robust immune system, carotenoids contribute to overall health and well-being.

*Coloration and attractiveness*: Carotenoids are responsible for the vibrant colors seen in many fruits, vegetables, and flowers. These colors play a role in attracting pollinators and seed dispersers, contributing to the reproductive success of plants. Additionally, carotenoid-rich fruits and vegetables are often associated with higher nutritional value, making them visually appealing and enticing for consumption.

Overall, carotenoids have diverse physiological functions and are considered essential components of a healthy diet. Incorporating a variety of carotenoid-rich foods, such as carrots, tomatoes, spinach, and peppers, can provide numerous health benefits and support overall well-being (**Figure 1**).

*Overview of carotenoid-rich foods*: Carotenoids are a group of pigments found in various fruits, vegetables, and other plant-based foods. They are responsible for the vibrant colors we see in many natural foods, ranging from the deep red of tomatoes to the bright orange of carrots. Beyond their visual appeal, carotenoids also offer a multitude of health benefits due to their antioxidant properties and potential role in supporting overall well-being. In this article, we will explore the world of carotenoidrich foods and their impact on human health [18, 19].

#### **2.5 Dietary sources of carotenoids**

Carotenoids are a group of pigments found in various fruits, vegetables, and other plant-based foods. These natural compounds are known for their vibrant colors, ranging from red and orange to yellow and green. Apart from adding visual appeal to our meals, carotenoids also offer numerous health benefits. They act as potent antioxidants, supporting our immune system, promoting eye health, and reducing the risk of chronic diseases. Let us explore some common dietary sources of carotenoids and discover how we can incorporate them into our daily diet (**Figure 1**; **Table 1**).

Remember that cooking methods can affect the carotenoid content of foods. While some carotenoids are heat-stable, others may degrade with prolonged cooking or high temperatures. To retain the maximum amount of carotenoids, consider lightly steaming or sautéing vegetables instead of boiling them. Pair carotenoid-rich foods with a source of healthy fats, as carotenoids are fat-soluble and their absorption is enhanced in the presence of fats. Incorporating a variety of these carotenoid-rich foods into your diet can provide numerous health benefits and add vibrancy to your meals. So, enjoy the colors of the rainbow on your plate and reap the rewards of these nutrientpacked foods.

#### *2.5.1 Carotenoids content in fruits and vegetables and in grains and animal products*

When it comes to maintaining a healthy diet, consuming a variety of fruits, vegetables, grains and animal products is essential. Besides their delicious flavors and nutritional profiles, these foods also provide a rich source of pigments called carotenoids. Carotenoids are natural compounds that give fruits, vegetables, grains, and even certain animal products their vibrant colors. In this article, we will delve into the



*Carotenoids: Sources, Bioavailability and Their Role in Human Nutrition DOI: http://dx.doi.org/10.5772/intechopen.113012*


 *Dietary sources of carotenoids and its health benefits.* fascinating world of carotenoids, exploring their content in fruits and vegetables as well as their presence in grains and animal products.

#### *2.5.2 Carotenoid content in fruits and vegetables*

Fruits and vegetables are known for their abundant carotenoid content, making them valuable components of a well-balanced diet. Carotenoids are responsible for the vibrant red, orange, and yellow hues seen in tomatoes, carrots, peppers, sweet potatoes, and mangoes, among others. The most common carotenoids found in fruits and vegetables include beta-carotene, lycopene, lutein, and zeaxanthin. Beta-carotene is commonly found in orange and yellow fruits and vegetables, such as apricots, cantaloupes, and carrots. Once consumed, it is converted by the body into vitamin A, which plays a crucial role in vision, immune function, and skin health. Lycopene, a powerful antioxidant, is abundant in tomatoes, watermelons, and pink grapefruits, and is believed to have potential health benefits, particularly in reducing the risk of certain cancers. Lutein and zeaxanthin, found in leafy greens like spinach and kale, are known for their role in promoting eye health and protecting against age-related macular degeneration.

#### *2.5.3 Carotenoids in grains and animal products*

While fruits and vegetables are prominent sources of carotenoids, these compounds can also be found in other food groups. Grains, such as corn and wheat, contain carotenoids like lutein and zeaxanthin, contributing to their yellow color. However, the carotenoid content in grains is relatively lower compared to that in fruits and vegetables. Certain animal products also contain carotenoids due to the animals' diets. For instance, eggs are a notable source of lutein and zeaxanthin, as chickens are fed a diet rich in these carotenoids. Similarly, farmed salmon, trout, and shrimp acquire their pinkish color from consuming carotenoid-rich algae or krill. These carotenoids, when consumed by humans through these animal products, can provide additional health benefits.

#### *2.5.4 Food sources of carotenoids*

To incorporate carotenoids into your diet, include a variety of colorful fruits and vegetables. Some excellent sources of carotenoids include carrots, sweet potatoes, tomatoes, spinach, kale, red bell peppers, apricots, mangoes, papayas, and oranges. Consuming these foods raw or lightly cooked can help preserve their carotenoid content. Additionally, pairing them with a source of fat, such as olive oil or avocado, may enhance carotenoid absorption [20] (**Table 1**).

#### *2.5.5 Absorption and bioavailability*

While carotenoids are abundant in many foods, their bioavailability can vary. The presence of dietary fat, cooking methods, and food processing can influence the absorption of carotenoids. Combining carotenoid-rich foods with healthy fats, like olive oil or nuts, can improve their absorption. Moreover, some studies suggest that lightly cooking or puréeing certain vegetables, such as tomatoes, can enhance the release of carotenoids from the plant cells, making them more bioavailable for our bodies to absorb.

#### *2.5.6 Dietary considerations*

While carotenoids offer numerous health benefits, it's important to remember that they work synergistically with other nutrients and compounds present in whole foods. Rather than relying solely on carotenoid supplements, it is best to obtain these pigments through a varied and balanced diet. Aim to consume a wide range of fruits, vegetables, and whole grains to ensure a diverse intake of carotenoids and other essential nutrients.

#### *2.5.7 Individual variations*

It's worth noting that individual variations in carotenoid absorption and metabolism exist. Factors such as age, genetics, gut health, and overall dietary patterns can influence how effectively our bodies utilize carotenoids. Additionally, the presence of certain medical conditions or the use of medications may impact carotenoid absorption or utilization. Consulting with a healthcare professional or registered dietitian can provide personalized guidance on incorporating carotenoidrich foods into your diet.

Carotenoid-rich foods not only add vibrancy to our plates but also contribute to our overall health and well-being. The diverse range of carotenoids present in fruits and vegetables offer antioxidant protection, support eye health, promote cardiovascular wellness, and may even help reduce the risk of certain cancers. By incorporating a variety of colorful plant-based foods into our diets, we can harness the benefits of carotenoids and enhance our overall nutritional intake. So, embrace the rainbow of colors on your plate and enjoy the abundance of carotenoid-rich foods nature has to offer.

#### **2.6 Mechanisms of action of carotenoids**

#### *2.6.1 Exploring cellular and molecular effects*

Carotenoids are a group of naturally occurring pigments widely found in fruits, vegetables, and other plant-based foods. These compounds have gained significant attention due to their potential health benefits, including their role as antioxidants and their association with a reduced risk of chronic diseases. Understanding the mechanisms of action of carotenoids at the cellular and molecular levels is crucial for unraveling their beneficial effects. In this article, we delve into the intricate mechanisms by which carotenoids exert their influence, focusing on their impact on gene expression and interactions with other bioactive compounds.

#### *2.6.2 Cellular and molecular mechanisms*

*Antioxidant activity*: One of the primary mechanisms through which carotenoids exert their effects is by acting as antioxidants. Carotenoids, such as beta-carotene and lycopene, possess the ability to neutralize reactive oxygen species (ROS) and prevent oxidative damage to cells and tissues. By scavenging free radicals, carotenoids help maintain cellular integrity and protect against oxidative stress-related diseases.

*Anti-inflammatory effects*: Carotenoids have been shown to exhibit anti-inflammatory properties by modulating various signaling pathways involved in inflammation. They can inhibit the production of pro-inflammatory molecules, such as cytokines and chemokines, thereby reducing inflammation and its associated damage.

*Carotenoids: Sources, Bioavailability and Their Role in Human Nutrition DOI: http://dx.doi.org/10.5772/intechopen.113012*

Additionally, carotenoids can suppress the activation of transcription factors that regulate inflammatory gene expression.

*Role of carotenoids in gene expression*: Carotenoids have been found to influence gene expression through multiple mechanisms. Here are a few key ways in which carotenoids impact gene regulation:

*Activation of nuclear receptors*: Carotenoids can bind to specific nuclear receptors, such as the retinoic acid receptor (RAR) and retinoid X receptor (RXR). This binding activates these receptors, which in turn regulate the expression of target genes involved in various cellular processes, including growth, differentiation, and immune response.

*Modulation of transcription factors*: Carotenoids can interact with transcription factors, such as nuclear factor-kappa B (NF-κB) and activator protein-1 (AP-1), which play crucial roles in controlling gene expression related to inflammation and immune response. By interfering with these transcription factors, carotenoids can alter the expression of downstream genes involved in these pathways.

#### **3. Biological significance of carotenoids in human health**

#### **3.1 Importance of carotenoids in human health**

In the pursuit of maintaining good health and well-being, our diet plays a vital role. Among the various nutrients and compounds that contribute to our overall health, carotenoids hold a special place. Carotenoids are a group of pigments found in plants, algae and certain bacteria. They are responsible for the vibrant colors seen in fruits, vegetables and flowers. Beyond their esthetic appeal, carotenoids offer a range of health benefits, making them an essential component of a balanced diet. This article explores the significance of carotenoids in human health and the reasons why we should incorporate them into our daily lives.

#### **3.2 Cardiovascular health**

Numerous studies suggest that carotenoids, especially lycopene, beta-carotene, and lutein, may promote cardiovascular health. These compounds have been associated with a lower risk of heart disease and stroke, possibly due to their antioxidant and antiinflammatory effects. Carotenoids may help reduce oxidative stress, improve blood flow, and prevent the oxidation of LDL cholesterol, a major risk factor for heart disease [21].

#### **3.3 Cancer prevention**

Certain carotenoids have demonstrated potential in reducing the risk of various types of cancer. Lycopene, found in tomatoes and watermelon, has been associated with a lower risk of prostate cancer. Beta-carotene, abundant in carrots and sweet potatoes, may help protect against lung and other cancers. However, it's important to note that the protective effects of carotenoids may vary depending on individual factors and the overall diet [22].

#### **3.4 Powerful antioxidant properties**

Carotenoids act as potent antioxidants in the human body. They help neutralize harmful free radicals, which are unstable molecules that can cause damage to cells and DNA. By scavenging these free radicals, carotenoids play a crucial role in reducing oxidative stress and combating inflammation. This, in turn, contributes to the prevention of chronic diseases such as cardiovascular ailments, certain types of cancer, and age-related macular degeneration [23].

#### **3.5 Vision and eye health**

Lutein and zeaxanthin, two prominent carotenoids, are particularly beneficial for eye health. They accumulate in the macula of the eye, where they help filter harmful high-energy blue light and protect against oxidative damage. Regular consumption of carotenoid-rich foods has been linked to a reduced risk of age-related macular degeneration (AMD), cataracts, and other vision-related conditions [24].

Some carotenoids, such as lutein and zeaxanthin, are concentrated in the macula of the eye. They play a crucial role in maintaining healthy vision by filtering harmful blue light and protecting the retina from oxidative damage. These carotenoids are associated with a reduced risk of age-related macular degeneration, a leading cause of blindness in the elderly.

One specific carotenoid, namely lutein and zeaxanthin, is especially important for maintaining optimal vision and eye health. These carotenoids accumulate in the macula of the eye and act as a natural filter for harmful ultraviolet (UV) light and high-energy blue light. They help protect the retina from oxidative damage caused by these rays, reducing the risk of cataracts and age-related macular degeneration (AMD). Regular intake of foods rich in lutein and zeaxanthin, such as spinach, kale, and broccoli, can promote long-term eye health [11].

#### **3.6 Boosting immunity**

A robust immune system is vital for fighting off infections and diseases. Carotenoids play a crucial role in supporting the immune system by enhancing its functioning. They help regulate immune cell activity, promote the production of antibodies, and strengthen the body's defense mechanisms. Beta-carotene, found in foods like carrots, sweet potatoes, and bell peppers, is particularly renowned for its immune-boosting properties [25].

#### **3.7 Skin health and sun protection**

Carotenoids contribute to maintaining healthy skin from within. They help protect the skin against damage caused by exposure to harmful UV rays. While carotenoids themselves do not act as sunscreens, studies have suggested that they possess photoprotective properties and can help reduce the risk of sunburn. Consuming carotenoid-rich foods alongside using sunscreen and adopting other sun-safe practices can provide added protection for the skin [26, 27].

#### **3.8 Potential cancer prevention**

Several studies have indicated that carotenoids may have a role in cancer prevention. Their antioxidant and anti-inflammatory properties help combat cellular damage and reduce the risk of various types of cancer, including lung, breast, prostate, and colorectal cancer. Although more research is needed to fully understand the

#### *Carotenoids: Sources, Bioavailability and Their Role in Human Nutrition DOI: http://dx.doi.org/10.5772/intechopen.113012*

mechanisms involved, incorporating a variety of carotenoid-rich foods into the diet may contribute to a lower cancer risk.

Carotenoids are not only responsible for the beautiful hues of fruits and vegetables but also offer an array of health benefits. Their antioxidant properties, ability to support vision and eye health, immune-boosting effects, skin protection, and potential cancer-preventive properties make them essential for overall well-being. To maximize the intake of carotenoids, it is advisable to consume a diverse range of colorful fruits and vegetables, aiming for a balanced and nutritious diet. By incorporating these vibrant plant pigments into our daily lives, we can enhance our health and protect ourselves against various diseases, paving the way for a healthier and happier future [28].

#### **4. Factors effecting carotenoid levels in foods**

Carotenoids are a group of pigments responsible for the vibrant colors seen in many fruits, vegetables, and other plant-based foods. Beyond their visual appeal, carotenoids play a crucial role in human health as potent antioxidants and precursors of vitamin A. These compounds have been associated with numerous health benefits, including reducing the risk of chronic diseases such as cancer and cardiovascular diseases, as well as supporting eye health and immune function. However, the levels of carotenoids in food can vary significantly due to various factors. Understanding these factors is essential for optimizing carotenoid intake and promoting overall well-being.

#### **4.1 Plant varieties and species**

The type and variety of plant species play a fundamental role in determining carotenoid levels in food. Different plant species contain varying types and concentrations of carotenoids. For example, fruits like tomatoes and watermelons are rich in lycopene, while leafy greens such as spinach and kale are abundant in lutein and zeaxanthin. Additionally, within a particular species, variations in carotenoid content may exist due to genetic factors or breeding practices [29–31].

#### *4.1.1 Ripeness and maturity*

The ripeness and maturity of fruits and vegetables are critical factors affecting carotenoid levels. Carotenoid concentrations tend to increase as fruits and vegetables ripen, reaching their peak at full maturity. For example, green tomatoes have lower carotenoid content compared to fully ripe red tomatoes. However, it is important to note that excessive ripening or prolonged storage can lead to carotenoid degradation, reducing their levels.

#### *4.1.2 Agricultural practices*

Agricultural practices, including farming techniques, soil conditions, and fertilization methods, influence carotenoid levels in food. Plants grown in nutrient-rich soils tend to produce higher levels of carotenoids. Additionally, organic farming methods that promote soil health and minimize the use of chemical pesticides and fertilizers have been shown to enhance carotenoid content in crops compared to conventional farming practices.

#### *4.1.3 Post-harvest handling and storage*

Proper post-harvest handling and storage conditions are crucial for preserving carotenoid levels in food. Exposure to light, heat, and oxygen can lead to carotenoid degradation. Therefore, minimizing these factors during transportation, storage, and food processing is essential. Controlled temperature and humidity, as well as suitable packaging, can help maintain carotenoid stability and retention.

#### *4.1.4 Food processing and preparation*

Food processing techniques and cooking methods can significantly affect carotenoid levels. While some processes, such as blanching or steaming, can enhance carotenoid bioavailability by breaking down cell walls and improving nutrient release, other methods like boiling or frying may result in losses due to leaching into cooking water or degradation from high heat exposure. Similarly, cutting, chopping, and juicing can lead to carotenoid losses through oxidation and enzymatic reactions.

#### *4.1.5 Dietary fat and absorption*

Carotenoids are fat-soluble compounds, meaning they require the presence of dietary fat for optimal absorption in the body. Consuming carotenoid-rich foods with a source of healthy fats, such as olive oil or avocado, can enhance their bioavailability. Including fat in meals can improve carotenoid absorption and maximize their health benefits. Understanding the factors that affect carotenoid levels in food is essential for making informed dietary choices and optimizing nutrient intake. By considering factors such as plant varieties, ripeness, agricultural practices, post-harvest handling, food processing, and dietary fat, individuals can maximize their consumption of carotenoids and promote overall well-being.

#### **4.2 Bioavailability and of carotenoids**

Carotenoids are known for their antioxidant properties and have been associated with a reduced risk of chronic diseases, including cardiovascular diseases, certain types of cancer, and age-related macular degeneration. However, the bioavailability and metabolism of carotenoids play a crucial role in determining their potential health benefits. In this article, we explore the journey of carotenoids through our bodies, from ingestion to absorption, distribution, and metabolism. Carotenoid bioavailability is defined as the fraction of carotenoid released from food that is absorbed in the intestine and made available for physiological processes or storage [17].

The nature of the food matrix containing carotenoids strongly affects their bioavailability. Due to their hydrophobic nature and location in plant tissues (plastids), carotenoid bioavailability in raw fruits and vegetables is limited. Therefore, carotenoids must be released from the cellular matrix and incorporated into a lipid fraction (micelles) during digestion to be absorbed [32].

Carotenoids are released from food mechanically by chewing, and chemically by the action of digestive enzymes (amylases, lipases, pepsin) and hydrochloric acid in the stomach [33]. These processes contribute to particle size reduction, thus increasing contact area for pancreatic lipases, bile salts, and enzymes, such as pancreatic

#### *Carotenoids: Sources, Bioavailability and Their Role in Human Nutrition DOI: http://dx.doi.org/10.5772/intechopen.113012*

amylases, nucleosidases, trypsinogen, chymotrypsinogen, carboxypeptidase, elastases, phospholipases, and carboxyl lipase ester, and the release of carotenoids and their incorporation into micelles [33].

Bioavailability refers to the proportion of a nutrient that is absorbed and becomes available for use in the body. While carotenoids are abundant in many plant-based foods, their bioavailability varies depending on several factors, including food matrix, food processing and individual factors.

*Food matrix*: The carotenoid content and physical structure of the food source influence their bioavailability. Carotenoids are often encapsulated within the plant's cell walls, making them less accessible for absorption. Cooking or processing methods that break down these structures can enhance carotenoid release and subsequent absorption. For example, heating tomatoes or processing them into tomato sauce increases the bioavailability of the carotenoid lycopene.

*Food processing*: Processing techniques like chopping, pureeing, or juicing can improve carotenoid bioavailability by breaking down the plant's cell walls. However, some carotenoids are sensitive to heat, oxygen, and light. Thus, excessive processing or prolonged cooking may lead to carotenoid degradation and loss.

*Individual factors*: The efficiency of carotenoid absorption varies among individuals and depends on factors such as age, genetic variation, gut health, and the presence of dietary fats. Carotenoids are fat-soluble compounds, meaning they require dietary fat for optimal absorption. Consuming carotenoid-rich foods with a source of fat, such as olive oil or avocado, enhances their absorption.

#### **4.3 Absorption, transport and tissue distribution**

Once carotenoids are released from the food matrix and reach the small intestine, they undergo a process called micellar solubilization, facilitated by bile salts and pancreatic lipases. This process converts carotenoids into a more absorbable form. The efficiency of absorption varies among carotenoids, with some being better absorbed than others.

*Efficient absorption*: Carotenoids such as beta-carotene, alpha-carotene, and beta-cryptoxanthin are efficiently absorbed. They are incorporated into micelles and absorbed directly into intestinal cells. From there, they enter the lymphatic system and then the bloodstream, where they bind to carrier proteins for transport.

*Limited absorption*: Certain carotenoids, such as lycopene and lutein, have lower bioavailability due to their poor solubility in water. However, the presence of dietary fat and the simultaneous consumption of carotenoids with oil-rich foods can enhance their absorption. Lycopene, found in tomatoes, is more efficiently absorbed when consumed with a source of dietary fat.

*Metabolism and conversion*: Once in the bloodstream, carotenoids are transported to various tissues throughout the body. Some carotenoids, like beta-carotene, are converted into active forms of vitamin A (retinol) in the liver. Retinol plays a crucial role in vision, growth, and immune function. The conversion rate of beta-carotene to retinol varies among individuals and is influenced by genetic factors, dietary factors, and the body's vitamin A status.

Carotenoids that are not converted into vitamin A are metabolized in different ways. Carotenoid metabolites, such as apo-carotenals and apo-carotenols, are formed through enzymatic reactions. These metabolites have been found to possess their own biological activities and contribute to the health benefits associated with carotenoid consumption.

Furthermore, carotenoids are known for their antioxidant properties, which help protect cells from damage caused by free radicals. They achieve this by neutralizing reactive oxygen species and preventing oxidative stress. Carotenoids also exhibit anti-inflammatory properties and support immune function, contributing to overall health and well-being.

It's important to note that the absorption, distribution, and metabolism of carotenoids can be influenced by various factors. For instance, certain medical conditions, such as malabsorption disorders or liver disease, can affect carotenoid absorption and metabolism. Additionally, the presence of other dietary components, such as fiber or certain medications, may interfere with carotenoid bioavailability.

#### **5. Considerations for maximizing carotenoid benefits**

To optimize the bioavailability and health benefits of carotenoids, consider the following:

*Include a variety of carotenoid-rich foods in your diet*: Consume a diverse range of fruits and vegetables, such as carrots, spinach, tomatoes, sweet potatoes, kale, and bell peppers. Each of these foods contains different types of carotenoids, ensuring a broader spectrum of health benefits.

*Pair carotenoid-rich foods with healthy fats*: As carotenoids are fat-soluble, consuming them with a source of dietary fat enhances their absorption. Add a drizzle of olive oil to your salads, sauté vegetables in coconut oil, or enjoy avocados alongside carotenoid-rich dishes.

*Opt for minimal processing*: While cooking or processing can enhance carotenoid release, excessive processing or prolonged cooking at high temperatures may lead to nutrient loss. Choose cooking methods like steaming or stir-frying, which retain more nutrients compared to boiling or deep-frying.

*Consider food combinations*: Some carotenoids, like lycopene in tomatoes, are better absorbed when consumed in cooked or processed forms. Combining tomatoes with a source of fat, such as olive oil, further enhances lycopene absorption.

*Practice balanced and varied eating habits*: Consuming a well-rounded diet that includes a variety of nutrients and phytochemicals promotes overall health. Remember that carotenoids work synergistically with other compounds in fruits and vegetables to provide their full range of benefits.

Carotenoids are a fascinating group of pigments found in many plant-based foods. Their bioavailability and metabolism determine the extent to which they can exert their beneficial effects on human health. While factors like food matrix, processing methods, and individual differences can influence carotenoid absorption and utilization, incorporating a diverse range of carotenoid-rich foods, along with dietary fat, can maximize their bioavailability. By understanding the bioavailability and metabolism of carotenoids, we can harness the power of these vibrant plant pigments and reap their numerous health benefits.

#### **5.1 Health benefits and importance of carotenoids**

Carotenoids are not only responsible for the vibrant colors of foods but also offer numerous health benefits. These compounds act as antioxidants, protecting the body

#### *Carotenoids: Sources, Bioavailability and Their Role in Human Nutrition DOI: http://dx.doi.org/10.5772/intechopen.113012*

from harmful free radicals and oxidative stress. As such, they are associated with a reduced risk of chronic diseases, including certain cancers, cardiovascular diseases, and age-related macular degeneration.

Carotenoids are a group of natural pigments responsible for the vibrant colors in fruits and vegetables. They are widely known for their antioxidant properties and have been linked to numerous health benefits. These powerful compounds play a crucial role in maintaining overall health and reducing the risk of chronic diseases. Let us explore some of the key health benefits of carotenoids [11].

Additionally, carotenoids play a vital role in supporting immune function, promoting healthy skin, and contributing to overall well-being. The consumption of a diverse range of fruits, vegetables, grains, and animal products rich in carotenoids can help ensure an adequate intake of these beneficial compounds.

Carotenoids are natural pigments found in various fruits, vegetables, grains, and animal products, providing not only vibrant colors but also significant health benefits. Fruits and vegetables, with their high carotenoid content, are excellent sources for these compounds, including beta-carotene, lycopene, lutein, and zeaxanthin. Grains and animal products can also contribute to carotenoid intake, albeit to a lesser extent While the carotenoid content in grains is relatively lower, they still offer some health benefits and contribute to the overall carotenoid intake. Animal products, on the other hand, acquire carotenoids through the animals' diets, providing an additional source of these compounds for humans.

Consuming a variety of fruits and vegetables, including those rich in carotenoids, is essential for a well-rounded and nutritious diet. Different carotenoids offer specific benefits. For example, beta-carotene is known for its conversion into vitamin A and its role in vision and immune function. Lycopene has been associated with a reduced risk of certain cancers, while lutein and zeaxanthin promote eye health and protect against macular degeneration [22].

Including carotenoid-rich foods in your diet can have a positive impact on your health. Here are some tips to incorporate these foods:

*Eat a rainbow*: Include a diverse range of fruits and vegetables in various colors to ensure a wide spectrum of carotenoids.

*Cook smart*: Some carotenoids are better absorbed when cooked or consumed with healthy fats. For instance, lycopene in tomatoes is more readily available when cooked and paired with olive oil.

*Go green*: Leafy green vegetables like spinach, kale, and collard greens are excellent sources of lutein and zeaxanthin.

*Enjoy seasonal produce*: Opt for locally grown and seasonal fruits and vegetables, as they tend to be fresher and higher in nutrient content.

*Choose pastured animal products*: When consuming animal products like eggs or poultry, opt for those sourced from pasture-raised animals that have a natural diet and access to carotenoid-rich foods.

In conclusion, carotenoids are natural pigments found in fruits, vegetables, grains, and animal products. They not only provide vibrant colors to our food but also offer numerous health benefits, including antioxidant properties and the potential to reduce the risk of chronic diseases. By incorporating a wide variety of carotenoidrich foods into our diets, we can support our overall well-being and promote optimal health. So, let us embrace the colorful world of carotenoids and enjoy the benefits they bring to our plates and our bodies.

*Antioxidant and anti-inflammatory properties*: Carotenoids act as potent antioxidants, helping to neutralize harmful free radicals in the body. Free radicals are highly reactive molecules that can damage cells and contribute to chronic inflammation, which is associated with various diseases, including cancer, heart disease and diabetes. By scavenging these free radicals, carotenoids help protect against oxidative stress and reduce inflammation, promoting overall well-being.

*Carotenoids and cancer prevention*: Carotenoids have been extensively studied for their potential role in cancer prevention. These compounds exhibit anticancer properties by inhibiting the growth of cancer cells, reducing DNA damage, and boosting the immune system. Specific carotenoids such as beta-carotene, lycopene, and lutein have shown promising results in reducing the risk of certain cancers, including lung, prostate, breast, and colorectal cancer.

*Carotenoids and cardiovascular health*: Several studies have demonstrated the positive effects of carotenoids on heart health. Carotenoids help lower the risk of cardiovascular diseases by reducing oxidative stress, inflammation, and the oxidation of LDL cholesterol (the "bad" cholesterol). Moreover, carotenoids have been associated with improved blood vessel function, reduced arterial stiffness, and lowered blood pressure. Including carotenoid-rich foods in your diet may help maintain a healthy heart.

*Carotenoids and age-related macular degeneration*: Age-related macular degeneration (AMD) is a leading cause of vision loss in older adults. Carotenoids, particularly lutein and zeaxanthin, accumulate in the macula of the eye and act as protective pigments. They help filter harmful blue light, reduce oxidative damage, and prevent the formation of age-related lesions in the macula. Studies suggest that a diet rich in carotenoids can lower the risk of developing AMD and slow its progression.

*Other potential health effects of carotenoids*: Beyond their well-established benefits, carotenoids may offer additional health advantages. Research suggests that these compounds may enhance immune function, support skin health by protecting against UV-induced damage, and promote cognitive health by reducing the risk of age-related cognitive decline and neurodegenerative diseases like Alzheimer's.

To reap the health benefits of carotenoids, it is important to consume a diverse range of fruits and vegetables. Foods such as carrots, sweet potatoes, tomatoes, spinach, kale, peppers, mangoes, papayas, and oranges are excellent sources of carotenoids. To enhance their absorption, pair carotenoid-rich foods with healthy fats, such as olive oil or avocados.

While carotenoids are generally safe and well-tolerated when consumed through food, it is essential to avoid excessive intake of carotenoid supplements. High-dose supplementation may not provide the same benefits as a well-balanced diet and can even lead to adverse effects.

Carotenoids offer a wide array of health benefits, thanks to their antioxidant and anti-inflammatory properties. From reducing the risk of chronic diseases like cancer and cardiovascular disorders to promoting eye health and supporting cognitive function, incorporating carotenoid-rich foods into your diet can contribute to overall well-being. So, make sure to fill your plate with a colorful assortment of fruits and vegetables to harness the power of carotenoids for optimal health.

*Interactions with other bioactive compounds*: Carotenoids can interact synergistically or antagonistically with other bioactive compounds, leading to enhanced or diminished effects on cellular processes. Some notable interactions include:

#### *Carotenoids: Sources, Bioavailability and Their Role in Human Nutrition DOI: http://dx.doi.org/10.5772/intechopen.113012*

*Vitamin E and carotenoids*: Vitamin E and carotenoids have been shown to work together synergistically to provide enhanced antioxidant protection. They regenerate each other's antioxidant capacity and help maintain the optimal functioning of cellular antioxidant defenses.

*Phytochemical combinations*: Carotenoids often coexist with other phytochemicals in fruits and vegetables. Studies have indicated that the combined consumption of carotenoids with other bioactive compounds, such as flavonoids, can result in greater health benefits than individual compounds alone. These combinations may have additive or synergistic effects on cellular mechanisms, contributing to improved health outcomes.

In conclusion, carotenoids exert their cellular and molecular effects through various mechanisms, including their antioxidant and anti-inflammatory activities. They can modulate gene expression by interacting with nuclear receptors and transcription factors. Moreover, carotenoids can interact with other bioactive compounds, influencing their overall impact on cellular processes. Further research is needed to fully understand the intricate mechanisms of action of carotenoids and their potential for therapeutic applications. Incorporating a diverse range of carotenoid-rich foods into our diets may offer a synergistic combination of health benefit, promoting overall well-being and disease prevention.

#### **5.2 Challenges and opportunities for increasing carotenoid consumption**

#### *5.2.1 Dietary interventions and promotion of carotenoid-rich foods challenges*

*Lack of awareness*: One of the primary challenges is the lack of awareness about carotenoids and their health benefits. Many individuals are unfamiliar with carotenoids and fail to recognize their significance in maintaining optimal health. Education campaigns and public health initiatives can help raise awareness and promote the consumption of carotenoid-rich foods.

*Limited availability*: Carotenoid-rich foods, such as certain fruits and vegetables, may not be easily accessible or affordable for everyone. This is particularly true in low-income areas or regions with limited agricultural resources. Efforts should be made to address food insecurity and improve the availability and affordability of carotenoid-rich foods.

*Food processing and cooking methods*: The processing and cooking methods used for food preparation can significantly impact carotenoid content. Carotenoids are sensitive to heat, light, and oxygen exposure, which can lead to their degradation. Promoting cooking methods that preserve carotenoids, such as steaming or stirfrying, can help retain their nutritional value.

*Taste preferences*: Some carotenoid-rich foods may have distinct flavors or textures that are not universally appealing. People's taste preferences, especially in younger populations, often lean towards processed or unhealthy foods lacking in carotenoids. Introducing innovative recipes, culinary techniques, and flavor combinations can make carotenoid-rich foods more appealing to a broader audience.

#### **5.3 Dietary interventions and promotion of carotenoid-rich foods opportunities**

*Dietary guidelines and policies*: Governments and health organizations can play a crucial role in promoting carotenoid consumption by incorporating them into dietary guidelines and policies. This includes emphasizing the importance of consuming a diverse range of fruits and vegetables, specifically those rich in carotenoids, and providing practical recommendations for incorporating them into daily meals.

*Food industry collaboration*: Collaboration between the food industry and health organizations can help increase the availability and accessibility of carotenoid-rich foods. Encouraging food manufacturers to fortify processed foods with carotenoids or develop new products that incorporate these beneficial compounds can provide more options for consumers.

*Nutrition education and promotion*: Integrating nutrition education into schools, workplaces, and healthcare settings can enhance awareness and understanding of carotenoids and their health benefits. Nutrition education programs can teach individuals how to identify carotenoid-rich foods, prepare them in a nutritious manner, and make informed dietary choices.

*Culinary innovation*: Chefs, culinary experts, and food influencers can play a pivotal role in increasing carotenoid consumption. By showcasing creative and appealing recipes that highlight the flavors and benefits of carotenoid-rich foods, they can inspire individuals to explore new culinary possibilities and incorporate these foods into their diets.

In conclusion Increasing carotenoid consumption is crucial for improving public health and reducing the risk of chronic diseases. While challenges such as lack of awareness, limited availability, and taste preferences exist, there are also promising opportunities to overcome them. By raising awareness, improving accessibility, promoting culinary innovation, and integrating nutrition education, we can pave the way for a healthier future, where carotenoid-rich foods play a more significant role in our diets. Embracing these opportunities will contribute to improved overall health and well-being for individuals and communities worldwide.

#### **5.4 Food fortification and supplementation programs**

Carotenoids are a class of natural pigments found in various fruits and vegetables, known for their potent antioxidant properties and potential health benefits. These compounds have gained significant attention in recent years due to their role in promoting overall well-being and reducing the risk of chronic diseases. However, many individuals fail to consume adequate amounts of carotenoid-rich foods in their regular diet, leading to a need for alternative strategies to address this nutritional gap. In this article, we will explore the importance of carotenoids, discuss food fortification and supplementation programs, examine cultural, economic, and social factors influencing consumption, and highlight future research directions in the field.

Carotenoids play a crucial role in maintaining human health by acting as antioxidants, protecting cells from damage caused by harmful free radicals. Additionally, specific carotenoids, such as beta-carotene, lycopene, and lutein, have been associated with a reduced risk of chronic diseases like cardiovascular disease, certain types of cancer, and age-related macular degeneration. Despite their potential benefits, many individuals do not consume enough carotenoid-rich foods in their daily diet. This is where food fortification and supplementation programs come into play. Food fortification involves adding specific nutrients, including carotenoids, to commonly consumed food items to increase their nutritional value. This approach aims to improve the dietary intake of carotenoids in populations that may have limited access to diverse food sources or suffer from nutrient deficiencies. Fortification programs have been successfully implemented for other nutrients, such as folic acid in flour,

#### *Carotenoids: Sources, Bioavailability and Their Role in Human Nutrition DOI: http://dx.doi.org/10.5772/intechopen.113012*

iodine in salt, and vitamin D in milk. Similarly, incorporating carotenoids into staple foods, such as cereals, oils, or dairy products, could help enhance their availability and ensure a more consistent intake among populations.

Supplementation programs, on the other hand, involve the use of carotenoid supplements in the form of pills, capsules, or liquid formulations. These programs are especially useful for individuals who may have difficulty consuming a varied diet or those with specific health conditions that require higher carotenoid levels. However, it is important to note that while supplementation can be beneficial in certain cases, it should not be considered a replacement for a balanced diet.

The success of carotenoid fortification and supplementation programs relies not only on the scientific evidence supporting their benefits but also on various cultural, economic, and social factors that influence consumption patterns. Cultural factors include food preferences, traditions, and culinary practices that may impact the acceptance and adoption of fortified foods. For example, in some cultures, traditional food preparation methods may result in the loss of carotenoids, limiting their bioavailability. Understanding these cultural aspects is crucial for developing effective strategies that align with the local context and encourage the consumption of carotenoid-rich foods.

Economic factors, such as the cost and availability of fortified products, also play a significant role. Fortification programs need to ensure that the cost of fortified foods remains affordable for the target population and that they are readily available in markets and distribution channels. Additionally, education and awareness campaigns are vital to inform consumers about the benefits of carotenoids, fortification programs, and suitable food choices. Social factors, including social norms, peer influence, and social support networks, can also impact individual choices and behaviors related to carotenoid consumption. Creating a supportive environment that promotes healthy eating habits and encourages the inclusion of carotenoid-rich foods can contribute to the success of fortification and supplementation initiatives.

Looking ahead, there are several exciting research directions in the field of carotenoids that can further enhance our understanding and utilization of these compounds. Unraveling the complex mechanisms of carotenoid action is essential for comprehending their interactions with other nutrients and their specific roles in different physiological processes. Identifying specific carotenoids for targeted health benefits is another promising avenue of research. While several carotenoids have been studied extensively, there is still much to discover about their individual effects on various aspects of health. By identifying the carotenoids that are most effective for specific health outcomes, tailored interventions can be developed to address specific needs.

Furthermore, developing effective strategies for increasing carotenoid intake is crucial for maximizing their potential health benefits. This involves not only fortification and supplementation programs but also initiatives that promote the consumption of natural, whole food sources of carotenoids. Encouraging the inclusion of a variety of fruits and vegetables in daily meals, providing education on their nutritional value, and promoting culinary creativity can all contribute to a higher intake of carotenoidrich foods.

In conclusion, carotenoids are valuable compounds with significant health benefits. However, many individuals fail to consume adequate amounts of carotenoid-rich foods, which necessitates the implementation of food fortification and supplementation programs. These programs can help bridge the nutritional gap and ensure a more consistent intake of carotenoids among populations. Nonetheless, the success of such

initiatives depends on understanding and addressing cultural, economic and social factors that influence consumption patterns. Future research should focus on unraveling the complex mechanisms of carotenoid action, identifying specific carotenoids for targeted health benefits, and developing effective strategies for increasing carotenoid intake. By advancing our knowledge and implementing evidence-based interventions, we can harness the potential of carotenoids to promote better health and well-being for all.

#### *5.4.1 Summary of key points*

Carotenoids are natural pigments found in plants, algae, and some bacteria. They are responsible for the vibrant colors of fruits and vegetables such as carrots, tomatoes, and spinach. Carotenoids play a crucial role in human health as they possess powerful antioxidant properties. Research has shown that these compounds can help prevent and manage various diseases, making them an important component of a healthy diet.

Carotenoids, such as beta-carotene, lycopene, and lutein, have been extensively studied for their potential health benefits. These compounds act as antioxidants, neutralizing harmful free radicals and protecting cells from oxidative damage. Oxidative stress has been linked to the development of chronic diseases, including cancer, cardiovascular disease, and age-related macular degeneration (AMD). By reducing oxidative stress, carotenoids contribute to the prevention and management of these conditions.

Numerous studies have demonstrated the association between carotenoid intake and a reduced risk of certain cancers. For example, beta-carotene has been shown to have a protective effect against lung cancer, while lycopene may lower the risk of prostate cancer. Similarly, lutein and zeaxanthin have been linked to a decreased risk of developing AMD, a leading cause of blindness in older adults.

Carotenoids also play a role in cardiovascular health. Research suggests that these compounds can help prevent the oxidation of low-density lipoprotein (LDL) cholesterol, known as "bad" cholesterol. When LDL cholesterol becomes oxidized, it contributes to the formation of plaque in the arteries, leading to atherosclerosis and an increased risk of heart disease. By reducing LDL oxidation, carotenoids contribute to the prevention of cardiovascular diseases.

Furthermore, carotenoids have shown promise in managing chronic inflammatory conditions. Inflammation is a key factor in the development and progression of conditions such as rheumatoid arthritis, asthma, and inflammatory bowel disease. The anti-inflammatory properties of carotenoids, particularly beta-carotene and lutein, have been observed in various studies, suggesting their potential as complementary therapies for these conditions.

While the existing research highlights the importance of carotenoids in disease prevention and management, further studies are needed to fully understand their mechanisms of action and optimize their use in clinical practice. Future research should focus on exploring the synergistic effects of different carotenoids and their interactions with other bioactive compounds. Additionally, studies examining the optimal dosage, bioavailability, and potential side effects of carotenoid supplementation would provide valuable insights.

Interventions are also needed to promote the consumption of carotenoid-rich foods in populations with low dietary intake. Public health campaigns and educational initiatives can raise awareness about the health benefits of carotenoids and encourage individuals to incorporate more fruits and vegetables into their diets. Moreover, policy changes that support the availability and affordability of fresh produce can help improve access to these important nutrients.

In conclusion, carotenoids play a significant role in disease prevention and management due to their antioxidant and anti-inflammatory properties. They have been associated with a reduced risk of various diseases, including cancer, cardiovascular disease, and AMD. However, further research is necessary to elucidate their mechanisms of action and optimize their use in clinical settings. Increased efforts are also required to promote the consumption of carotenoid-rich foods and improve access to these vital nutrients for better public health outcomes.

### **Author details**

Indu Sharma\*, Neeraj Khare and Archana Rai Nims Institute of Allied Medical Science and Technology, NIMS University Rajasthan, Jaipur, Rajasthan, India

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

© 2024 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 6**

## Bioactive Properties of the Pigment Astaxanthin from *Haematococcus pluvialis* in Human Health

*Janeth Galarza, Bryan Pillacela and Bertha Olivia Arredondo-Vega*

#### **Abstract**

Astaxanthin is a carotenoid with the most reported cellular antioxidant effect, providing significant protection. It is evident that various diseases related to oxidative stress are increasing in the population. Therefore, there is an interest in searching for new sources of bioactive compounds that can be applied to improve human health. The information presented here is based on a review of the most relevant scientific articles that have shed light on the current state of the potential effects of astaxanthin, both in mammalian cell lines and in humans. The model organism studied was the freshwater microalga *Haematococcus pluvialis*, which accumulates high concentrations of astaxanthin under stress conditions. The biological activity of astaxanthin described in this review demonstrates that it is a potent antioxidant without adverse effects. Therefore, natural astaxanthin derived from *Haematococcus pluvialis* could be safely used as a nutraceutical and for preventive and therapeutic purposes in human health.

**Keywords:** microalgae, astaxanthin, antioxidant power, carotenoid, *Haematococcus pluvialis*

#### **1. Introduction**

Astaxanthin (3,3′-dihydroxy-diketo-β,β′-carotene-4,4-dione) is a secondary carotenoid, which belongs to the xanthophyll family, it is naturally synthesized by photosynthetic organisms mainly microalgae, but it can also be found in a limited number of fungi, bacteria, and plants [1, 2]. It has been reported that the freshwater microalgae *Haematococcus pluvialis* under conditions of environmental stress protects its photosynthetic apparatus by transforming its vegetative state into an astaxanthin-rich aplanospore state. To date, it is the only microorganism with the greatest capacity to produce astaxanthin [3, 4].

Several studies reveal that astaxanthin obtained from natural sources is the most effective carotenoid with antioxidant and cell protective properties. It has been reported to have anti-aging, anti-carninogenic, and anti-inflammatory effects, and the ability to protect against exposure to solar radiation booster of the immune system, prevents

gastrointestinal, neurodegenerative, and ocular diseases, which is why it is considered the most promising natural antioxidant that has been reported to date [5, 6]. Other carotenoids such as B-carotene, canthaxanthin, zeaxanthin, lutein, act in synergy and make natural astaxanthin a more effective antioxidant than synthetic astaxanthin, making it more effective in the treatment of various diseases and of greater benefit to human health [6, 7]. So, it is necessary to consume it through a food diet [5, 8].

Worldwide, economic, technological, cultural, and scientific development has had an impact on eating habits that are usually risky and a disordered lifestyle. As a consequence, heart disease has increased, diabetes, hypertension, obesity, and metabolic syndrome [9, 10].

In addition to the current economic, social, and environmental crisis that the world is facing, there is also a rise in the occurrence and spread of various diseases among humans. Recognizing this problem, both the FAO and UN have called upon researchers, entrepreneurs, and economic and industrial sectors to explore new sources of healthy and sustainable natural foods that can cater to the vulnerable population of nations [11]. In this context, the natural pigment astaxanthin produced by the *Haematococcus pluvialis* microalgae is gaining and increasing attention due to its potent bioactivity and potential benefits for human health. Consequently, several researchers have dedicated their efforts to the cultivation and biotechnological applications of this microalgae [4].

However, despite synthetic astaxanthin being the most commonly form for sale worldwide, it should not be used as a nutritional supplement due to its petrochemical origin. Consequently, the Food and Drug Administration (FDA) has not authorized its use in human nutrition [12, 13]. Additionally, in 2008, the Food and Agriculture Organization of the United Nations (FAO) issued restrictive regulations on the use of synthetic dyes in the food and feed industry. These regulations have contributed to the increasing utilization of natural astaxanthin as a food coloring agent [14, 15].

Thus, this literature review highlights the consumption of natural astaxanthin produced by the microalgae *H. pluvialis* and its potential beneficial effects on human health.

#### **2. General information about astaxanthin**

#### **2.1 Definition and sources of production of astaxanthin**

Astaxanthin is a naturally occurring fat-soluble pigment synthesized by the photosynthetic organisms and is found in various natural environments, particularly aquatic environments. The red pigmentation observed in salmon, shrimp, lobster, and crab tissue is attributed to the presence of ataxanthin [16, 17]. Although astaxanthin can be synthesized by different microorganisms, its productivity is generally too low for commercial exploitation (**Table 1**). However, *H. pluvialis* stands out among these microorganisms, with a productivity of 2.64% in relation to its dry weight, making it the most important microalgal species in the world [20, 21, 26].

Additionally, astaxanthin is a secondary carotenoid, from the xanthophyll group, it has unique chemical properties based on its molecular structure, it has 2 carbonyl groups, 2 hydroxyl groups, and 11 conjugated ethylenic double bonds. The polyene character gives it a distinctive molecular structure, chemical properties, and light absorption characteristics. The presence of a keto group and a hydroxyl group at the cyclic ends of the molecule, gives it great reactive power (**Figure 1**). This explains some of its unique characteristics such as the ability to be esterified, the high antioxidant activity, and its amphipathic nature over other carotenoids [27, 28].

*Bioactive Properties of the Pigment Astaxanthin from* Haematococcus pluvialis *in Human… DOI: http://dx.doi.org/10.5772/intechopen.112085*


#### **Table 1.**

*Content of Astaxanthin produced by different microorganisms.*

**Figure 1.** *Molecular structure of astaxanthin.*

#### **2.2 Biological role of astaxanthin in** *Haematococcus pluvialis*

*Haematococcus pluvialis* is a unicellular microalga that thrives in freshwater environments. It belongs to the Chlorophyta division and exhibits a fascinating life cycle that undergoes transformations depending on environmental factors. The life cycle stages include: (A) Vegetative State: This is the green bi-flagellated oval cell stage, where the microalgae are actively growing and reproducing. (B) Initial Palmella State: When the cell experiences stress, it transitions into a non-flagellated spherical cell with a green coloration. This stage is also known as the palmella state. (C) Red Palmella State: Under stressful conditions, the cell undergoes a transition and develops a reddish coloration. (D) Aplanospore or Cyst: This stage is characterized by a

#### **Figure 2.**

*Different cell forms of the microalga* Haematococcus pluvialis*. (A) Green vegetative cell; (B) initial palmella; (C) Palmella under stress conditions; (D) Aplanospore predominantly red under stressful conditions. Source: Authors.*

predominantly red, spherical shape with a rigid cell wall. The cyst serves as a protective mechanism for the genetic material and photosynthetic machinery of the cell (as shown in **Figure 2**) [2, 29].

During the aplanospore/cyst stage, *Haematococcus pluvialis* experiences intense environmental stress. To safeguard its essential components, the microalgae produces astaxanthin, which accumulates in lipid vesicles and forms cytoplasmic globules, giving the cells their distinctive red coloration. Astaxanthin plays a crucial role in protecting the microalgae's genetic material and photosynthetic machinery during this critical stage [26, 30, 31].

#### **2.3 Metabolic pathway of astaxanthin synthesis in** *Haematacoccus pluvialis*

In *Haematococcus pluvialis*, numerous genes have been identified that are responsible for the synthesis of carotenoids, particularly in relation to astaxanthin biosynthesis. The study of these genes has provided valuable insights into the regulation of astaxanthin biosynthesis and a deeper understanding of its biological role in response to stress [20, 27, 32, 33].

The precursor for carotenoid synthesis is isopentenyl pyrophosphate (IPP) [34]. In higher plants, two distinct pathways have been identified for IPP biosynthesis: the mevalonate pathway in the cytosol and the non-mevalonate pathway in the chloroplast [35]. However, in unicellular green microalgae like *Haematococcus pluvialis* and *Chlamydomonas reinhardtii*, it is believed that IPP is synthesized exclusively through the non-mevalonate pathway. This is supported by the presence of the enzyme IPI (isomerase), which catalyzes the conversion of IPP to dimethylallyl diphosphate (DMAPP) within the plastids [27, 36, 37].

In the chloroplast of microalgae, the enzyme phytoene synthase (PSY) catalyzes the first step of carotenoid biosynthesis, which involves the condensation of two molecules of 20-carbon geranylgeranyl pyrophosphate (GGPP) to form a 40-carbon phytoene molecule, which serves as the precursor for all carotenoids, as shown in **Figure 3**. The subsequent desaturation reactions of PSY are catalyzed by two structurally similar enzymes, phytoene desaturase (PDS) and ζ-carotene desaturase (ZDS), converting the colorless phytoene into colored lycopene. The subsequent steps of the pathway lead to the synthesis of colored carotenoids, carried out by membrane-bound enzymes such as PDS and lycopene β-cyclase (LCY). The biosynthesis of astaxanthin in *H*. *pluvialis* follows the general carotenoid pathway up to the formation of β-carotene [4, 27, 30].

Studies using carotenogenic inhibitors and *in vitro* and *in vivo* analysis of astaxanthin synthesis in *H*. *pluvialis* have revealed the involvement of two enzymes, β-carotene ketolase (BKT) and β-carotene hydroxylase (CHY), in the conversion of β-carotene to astaxanthin. BKT converts β-carotene to canthaxanthin via an equinone intermediate, where CHYB participates in the formation of astaxanthin [39]. The genes for ZDS and carotenoid isomerase (CRTISO) have not yet been well studied in *H. pluvialis* [9, 36]. Although the specific steps of astaxanthin biosynthesis occur in the cytoplasm, the enzymes of the general carotenoid pathway are localized in the chloroplast [9, 32, 40].

#### **2.4 Extraction and quantification methods of astaxanthin from** *Haematococcus pluvialis*

Various extraction methods have been employed to extract astaxanthin from *Haematococcus pluvialis*. These methods involve the use of organic solvents such

*Bioactive Properties of the Pigment Astaxanthin from* Haematococcus pluvialis *in Human… DOI: http://dx.doi.org/10.5772/intechopen.112085*

**Figure 3.**

*Metabolic pathway of astaxanthin synthesis in* H. pluvialis*. Adapted from Bhosal, P. Bertein, P 2005 [38].*

as acetone, ethanol, ethyl acetate, n-hexane, dichloromethane, and methanol, as well as hydrophobic deep eutectic solvents (DES) based on oleic acid and terpenes [20, 41, 42]. Prior to extraction, the cysts of *H*. *pluvialis* need to be lysed. The extraction of total carotenoids is typically initiated through a series of sonication and centrifugation cycles until the sample becomes colorless [21].

Following the extraction of total carotenoids, the isolation of astaxanthin is facilitated by a de-esterification process. This can be achieved through saponification using KOH or NaOH [41], enzymatic hydrolysis with alkaline lipase [43], or cholesterol esterase treatment, which aids in chromatographic analysis, concentration and pigment yield. Astaxanthin extracts are then analyzed using high-performance liquid

#### **Figure 4.**

*Schematic diagram illustrating the astaxanthin extraction process using 100% acetone. The diagram showcases the various steps involved in the extraction procedure. Source: The authors.*

chromatography (HPLC) at a wavelength between 440 and 475 nm. The retention time and absorption spectrum are compared with known standards to identify and quantify astaxanthin [41, 44]. **Figure 4** provides a general overview of the astaxanthin extraction process.

#### **3. Bioactivity of astaxanthin in human health**

Various studies have demonstrated that astaxanthin is a carotenoid of considerable interest due to its potent bioactivity in human health. Below is a detailed overview of its potential.

#### **3.1 Antioxidant activity**

Oxygen is known to be an essential element for life. However, reactive oxygen species (ROS) and singlet oxygen are generated during cellular metabolism as a result of an imbalance between the production of free radicals and the cell's antioxidant mechanisms, leading to oxidative stress [45, 46]. ROS are highly unstable molecules that accumulate in cells in response to physiological stress, air pollution, tobacco smoke, exposure to chemicals, or ultraviolet (UV) radiation, causing severe damage to DNA, proteins, and lipid membranes [26, 47]. When DNA is damaged, cells fail to function normally, leading to numerous problems and diseases. To address these issues, the human body is designed to neutralize free radicals and singlet oxygen at a normal level by producing its own antioxidants. For example, it produces the enzyme superoxide dismutase, which is highly effective in eliminating free radical molecules, and other enzymes that quench singlet oxygen activity, thus protecting the cell from oxidative damage [46].

*Bioactive Properties of the Pigment Astaxanthin from* Haematococcus pluvialis *in Human… DOI: http://dx.doi.org/10.5772/intechopen.112085*

Currently, the amount of antioxidants produced by our bodies is insufficient to counteract the production of free radicals and singlet oxygen caused by stress. Therefore, it is necessary to enhance the levels of antioxidants through a healthy diet [7]. Consequently, nutritionists recommend incorporating natural antioxidants into our diets as a means of protection against our hectic lifestyles [48, 49]. Extensive research has demonstrated the efficacy of carotenoids such as astaxanthin and β-carotene as potent antioxidants that effectively hinder the activity of singlet oxygen. These compounds not only scavenge free radicals but also neutralize them, thereby safeguarding our body's cells from oxidation and degradation [10, 50–52].

#### **3.2 Anti-inflammatory effects**

The initial immune response to infection or irritation is inflammation, also known as the innate defense mechanism. However, certain inflammatory reactions can have detrimental effects on host cells or tissues, leading to various diseases including arthritis, hepatitis, gastritis, colitis, atherosclerosis, pneumonia, among others [9, 45]. Both *in vitro* and *in vivo* studies have demonstrated that astaxanthin exhibits superior anti-inflammatory effects compared to common medications [16]. Consequently, natural anti-inflammatory substances such as astaxanthin are extensively utilized for the prevention and management of inflammatory conditions due to their ability to inhibit the production of nitric oxide (NO), prostaglandin E2 (PGE2), and pro-inflammatory cytokines [1, 47]. Furthermore, research has shown that astaxanthin derived from the microalga *H*. *pluvialis* is effective in alleviating symptoms of ulcers caused by *Helicobacter pylori* and reducing gastric inflammation [48]. Based on these findings, it can be concluded that astaxanthin serves as an antiinflammatory agent, and its consumption may contribute to the reduction of DNA damage, the modulation of acute-phase protein levels, and the improvement of the immune response [8, 46, 49].

#### **3.3 Hepatoprotective effects**

The liver is a vital organ responsible for cellular catabolism and anabolism. It plays a crucial role in various functions, including the oxidation of lipids to generate energy, detoxification of harmful substances, and elimination of viruses, pathogenic bacteria, and damaged red blood cells [53]. These functions result in the production of substantial amounts of free radicals and oxidative byproducts, necessitating protective mechanisms to safeguard liver cells from oxidative damage [13]. Astaxanthin has demonstrated remarkable efficacy in protecting mammalian liver cells against lipid peroxidation, surpassing the cellular protection provided by vitamin E [16]. Additionally, astaxanthin and β-carotene have been shown to exhibit hepatoprotective properties by inhibiting oval cell proliferation and promoting cellular differentiation in hepatocytes and bile duct epithelial cells during liver regeneration. This is particularly significant in preventing liver cancer resulting from the inhibition of normal cellular differentiation in hepatocytes [10, 54]. Moreover, astaxanthin offers hepatic protection in cases of hepatic ischemia–reperfusion injury by reducing the formation of oxidant-induced protein carbonyls and the conversion of xanthine dehydrogenase to xanthine oxidase. The remarkable effects of astaxanthin observed in mammalian cells have led scientists to recommend its use as an antioxidant therapy for patients with chronic hepatitis C, aiming to prevent obesity, metabolic syndrome, and liver diseases associated with insulin resistance [7, 48].

#### **3.4 Antidiabetic activity**

Studies conducted on humans have consistently demonstrated that carotenoids play a crucial role in reducing the risk of developing type 2 diabetes mellitus (T2DM). Increased intake of carotenoids has been found to be associated with lower levels of glycated hemoglobin (HbA1c) [13, 45]. These findings establish a clear connection between carotenoid consumption and the reduction of T2DM risk. Thus, it is imperative to include natural carotenoids in the human diet as a preventive and therapeutic measure against T2DM [55, 56].

Among the various carotenoids investigated, astaxanthin stands out as one of the most extensively studied compounds. Astaxanthin has demonstrated significant potential in the management of diabetic patients by effectively reducing oxidative stress induced by hyperglycemia, enhancing insulin levels, and lowering blood glucose levels [49, 57]. Notably, astaxanthin exhibits superior antioxidant activity compared to other carotenoids such as lutein, β-carotene, and zeaxanthin, making it a safe and viable option for human consumption [15, 48].

#### **3.5 Cardiovascular activity**

Astaxanthin, among other carotenoids, exhibits remarkable therapeutic benefits in the management of cardiovascular diseases. This can be attributed to its unique physicochemical structure, which enables it to interact effectively with cell membranes and possesses distinct properties [13, 47]. A study conducted on hypertensive mice treated with natural astaxanthin revealed its ability to prevent atherosclerosis, significantly reduce blood pressure, and delay the occurrence of stroke. These findings indicate that astaxanthin holds the potential in safeguarding against hypertension and stroke [1]. Furthermore, in patients at risk of cardiovascular disease, astaxanthin has shown promise in the treatment of myocardial injuries, thrombolysis, and other heart-related conditions. In a separate study involving individuals from different age groups who consumed astaxanthin, elevated adiponectin levels, improved triglyceride levels, and enhanced high-density lipoprotein cholesterol levels were observed, irrespective of age [53, 55].

#### **3.6 Anticancer activity**

Scientific evidence supports the potent cancer chemopreventive properties of carotenoids, which are independent of their antioxidant activity or their potential to convert to retinoids [13]. Among these carotenoids, astaxanthin exhibits exceptional anticancer activity, distinguishing it from β-carotene and canthaxanthin. Astaxanthin has demonstrated significant inhibitory effects on the growth of various tumor cells, including oral fibrosarcoma, breast cancer cells, prostate cells, and embryonic fibroblasts, suggesting its potential application in cancer treatment and prevention [45, 53]. Moreover, studies have shown that astaxanthin possesses notable preventive effects on colon carcinogenesis and bladder carcinogenesis. It also exhibits the ability to suppress fibrosarcoma cell growth and enhance immunity against tumor antigens, indicating its potential for greater anti-tumor activity through immune response enhancement [58, 59].

Furthermore, several studies utilizing extracts from the microalga *H*. *pluvialis*, which contains astaxanthin, have demonstrated the inhibition of human colon cancer cell growth, including HCT-116, HT-29, LS-174, WiDr, and SW-480. This inhibition

is achieved by arresting cell cycle progression and promoting apoptosis or cell death [16, 49]. These findings suggest that *H*. *pluvialis* extracts may also exhibit equal or superior effects in the treatment and prevention of cancer.

#### **3.7 Neuroprotective effects**

The nervous system, characterized by its high content of unsaturated fats and iron (which possesses prooxidant properties), is susceptible to oxidative damage due to aerobic metabolism and blood supply. Oxidative stress has been identified as a causal factor in the pathogenesis of various neurodegenerative diseases, including Huntington's disease, Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis (ALS). Diets rich in antioxidants have shown significant potential in reducing the associated risks of these diseases [5, 12, 51].

Notably, natural astaxanthin has been found to possess the ability to traverse the blood–brain barrier in mammals, thereby extending its antioxidant benefits to brain tissue. By inhibiting oxidative stress, this antioxidant pigment has the potential to reduce free radical-induced damage caused by ischemia, cell death, neurodegeneration, and cerebral infarction. As a result, astaxanthin holds clinical promise in the treatment of vulnerable or susceptible patients to ischemic events. Its potent bioactivity is attributed to its intracellular inhibition of ROS and its neuroprotective effects observed in human neuroblastoma SH-SY5Y cells. Additionally, astaxanthin has been found to enhance the proliferation of neural stem cells and promote their neural osteogenic and adipogenic differentiation [60]. These findings collectively indicate that astaxanthin possesses potential antioxidant and mitochondria-protective effects, making it a promising candidate for the prevention and treatment of neurodegenerative diseases.

#### **3.8 Eye protective effects**

Recent human studies have provided compelling evidence regarding the ocular protective effects of astaxanthin extracted from the microalgae *H*. *pluvialis*. These studies have shown that astaxanthin supplementation significantly improves deep vision, critical flicker fusion, and eye fatigue [48]. Furthermore, it has been found to exert a substantial inhibitory effect on the development of choroidal neovascularization, a condition that can lead to severe vision problems and even blindness [9, 45].

Animal trials investigating the effects of astaxanthin on ocular health have also yielded promising results. Astaxanthin has demonstrated potential as a therapeutic agent for ocular inflammation, as it can interact with selenite, thereby delaying its precipitation in the crystalline lens and attenuating cataract formation. Moreover, in cases of high intraocular pressure, astaxanthin has been associated with a significant decrease in the percentage of apoptotic cells in the retina, highlighting its protective effect in ocular hypertension [16, 51]. Additionally, rats fed with astaxanthin have shown reduced damage to their retinal photoreceptors from ultraviolet radiation and faster recovery compared to animals that did not receive astaxanthin supplementation [60, 61].

#### **3.9 Skin protective effects**

The skin possesses inherent antioxidant agents that can effectively neutralize the harmful impacts of ROS and mitigate cellular damage. However, when the production of ROS reaches excessive levels as a result of exposure to ultraviolet (UV) radiation, these natural defenses become inadequate [62]. The accumulation of ROS within

cells leads to cell death, and an excessive level of cell death can manifest as wrinkles, skin dryness, and photoaging conditions such as skin inflammation, melanoma, and skin cancer [1, 14]. Previous studies have demonstrated the therapeutic potential of natural pigments in protecting the skin [62, 63]. Consequently, consumers show a preference for naturally derived compounds in their cosmetic products rather than chemically synthesized pigments [63].

In a study involving women aged over 40, which investigated the relationship between skin roughness and aging, a clear correlation was observed between the concentration of carotenoids and individuals with elevated antioxidant levels. These individuals exhibited noticeable improvements in wrinkles and skin roughness [5, 64]. Another trial assessed the systemic photoprotective effects against UV radiation-induced damage in human dermal fibroblasts using various carotenoids such as astaxanthin, canthaxanthin, and β-carotene. The findings indicated that astaxanthin exhibited a significantly high level of photoprotection, effectively mitigating UV-induced alterations. Furthermore, the uptake of astaxanthin by fibroblasts was found to be greater than that of other carotenoids. These results suggest that astaxanthin possesses superior preventive properties against photooxidative changes in dermal cells [9, 55].

#### **3.10 Effects on fertility**

Astaxanthin has also exhibited notable effects on fertility. Evidence in humans indicates that a nutritious diet featuring a high intake of antioxidants, such as astaxanthin, can serve as an affordable and safe means to enhance sperm quality and fertility [65]. Pilot trials conducted on infertile men, who received astaxanthin according to the guidelines set by the World Health Organization (WHO), revealed that this carotenoid significantly decreased levels of ROS and improved the secretion of inhibin B hormone by Sertoli cells. These findings suggest a positive impact of astaxanthin on sperm characteristics and fertility in infertile patients [51].

#### **3.11 Effects on the immune system**

Immune cells are highly susceptible to oxidative stress due to the high concentration of polyunsaturated fatty acids present in their plasma membranes. However, the use of astaxanthin can counteract this sensitivity, as it has been shown to decrease markers of oxidative DNA damage and inflammation, thereby enhancing immune response [64, 66, 67]. In *in vitro* immunology studies utilizing human blood cells, astaxanthin has also demonstrated immunomodulatory effects, exhibiting an enhancement in the production of immunoglobulins in response to T-cell-dependent stimuli [53].

Considering the close association between oxidative stress and impaired immune response in individuals with diabetes, an animal study demonstrated that astaxanthin could serve as a beneficial adjunct in the prophylaxis and recovery of lymphocyte dysfunctions associated with diabetes. This carotenoid was shown to restore redox balance and potentially exert an anti-apoptotic effect on lymphocytes [8, 16].

#### **4. Conclusions and outlook**

This review highlights the potential impact of astaxanthin, a pigment, on human health, particularly in the treatment and prevention of diseases associated with

*Bioactive Properties of the Pigment Astaxanthin from* Haematococcus pluvialis *in Human… DOI: http://dx.doi.org/10.5772/intechopen.112085*

oxidative stress. Among various carotenoids, astaxanthin stands out for its remarkable protective efficiency, attributed to its ability to penetrate the cell membrane and its unique chemical structure. *Haematococcus pluvialis*, a microalga, has been identified as the microorganism with the highest capacity for producing and accumulating astaxanthin under environmentally stressful conditions.

Having recognized the valuable properties of astaxanthin and its natural sourcing from *H*. *pluvialis*, it is recommended that researchers in the healthcare field conduct clinical trials involving human subjects. Such trials would provide insights into the functions of the pigment, the appropriate patient population, and the optimal dosage for disease prevention, treatment, and control. Furthermore, in less developed countries, it is essential to establish parameters for large-scale cultivation and stress conditions to achieve high astaxanthin production. Additionally, there is a need to explore cost-effective and environmentally friendly methods for pigment extraction, ensuring its suitability for human consumption.

#### **Acknowledgements**

The authors would like to thank the contribution of the projects INCYT-PNF-2017 M3112 and CUP 91870000.0000.384095- Peninsula de Santa Elena State University- Ecuador. And it has the permission of the Ministry of Environment, Water and Ecological Transition MAATE-DBI-CM-2022-0264.

#### **Conflict of interest**

The authors declare no conflict of interest.

#### **Author details**

Janeth Galarza1 \*, Bryan Pillacela1 and Bertha Olivia Arredondo-Vega2

1 Faculty of Marine Sciences, Santa Elena Peninsula State University, La Libertad, Ecuador

2 Microalgae Biotechnology Laboratory, Northwest Biological Research Center (CIBNOR), La Paz, Baja California Sur, Mexico

\*Address all correspondence to: jgalarza@upse.edu.ec

© 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.

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Section 4
