**3. Nutritional significance of breastfeeding**

human milk provides a large group of functional components which improve the newborn health, increase the immunity, and protect against the gastrointestinal and respiratory infections [3]. So, it was noted that breastfed infants suffer less gastrointestinal disorders and respiratory infections rather than formula-fed infants [4]. The exclusive breastfeeding pattern during the first 6 months of life was recommended by various health and breastfeeding organizations such as the American Academy of Pediatricians (AAP) and the American Academy

It is scientifically accepted that using the nutritional factors may decrease or prevent the extension of these diseases and its implications to the adult life. Nowadays, researchers and health and breastfeeding organizations are trying to discover the precise substances in human milk that seem to supply physiological benefits beyond its normal nutritional value which contribute earlier in delay, treatment or prevent some diseases [6]. Thus, these functional ingredients hold a great promise for future trends in human nutrition. Additionally, the relationship between milk consumption and human health requires a deeper understanding to uncover the protective role of some bioactive compounds, which naturally

Although human milk is considered the optimal food and supplies all the nutrient and some bioactive components, it is no longer sufficient to meet all the necessary nutritional requirements after 4–6 months of infant life [7]. In this case, infant formulas play an indispensable role in infant feeding. The formulas should be similar to mature human milk regarding its micronutrient and macronutrient contents. During the evolution of infant formulas, the manufacturers should take into account the necessary nutritional requirements of the newborns and infants and enrich the formulas with the functional ingredients which are naturally present in human milk [8]. The aim of this review is to present current knowledge regarding evidence on the importance of breastfeeding, the functionality of selected human milk ingredients, infant formulas as a human milk alternative, and the similarities and differences

It is well established that breastfeeding pattern of newborn provides more benefits for both mothers and their babies. It is well documented that breastfeeding not only provides the optimal nutrition [9] but also has many health benefits for both children and their mothers [10]. Breastfeeding pattern is positively associated with maternal sensitivity and with bonding between mother and infant [11]. It helps to build up a safe and full-of-feeling relationship between the mother and her infant and offers numerous other positive advantages. Breastfeeding mothers suffer less from certain serious diseases: reduced risk of certain cancers, including ovarian and breast cancer, type 2 diabetes, delayed resumption of menses, and more rapid postpartum weight loss. So, breastfeeding mothers are likely to be more health conscious, and, therefore, to promote healthy habits, which are likely to prevent overweight

of Family Physicians (AAFP) [5].

12 Selected Topics in Breastfeeding

present in human milk.

between human milk and infant formulas.

and obesity later in childhood [12].

**2. Meaning of breastfeeding for mothers and babies**

It is well established that infancy is the most important stage of human life where newborns are growing with high rate allowing to duplicate the infant weight in only 4–5 months. So, an adequate supply of nutrients represents paramount importance in this early stage of infant life. The breastfeeding of infants is obviously important to provide the needed nutrients and energy for the synthesis and deposition of new tissues from birth until 4–6 months of infant life.

The high metabolic requirements contrast with the limited ability of young infants to compensate for an inadequate supply of nutrients due to the diminished body reserves of nutrients and the immature homeostatic mechanisms. For example, the activity of some metabolic pathways and the kidney's ability to concentrate the urine are still low during the first 3–4 months of life. Young children may not be able to synthesize sufficient amounts of certain substrates considered as nonessential or dispensable since the limited capacity of the specific metabolic synthesis is not always sufficient to achieve the high requirements. Some nutrients considered nonessential in adults and older children can become indispensable for young infants that would be supplied in the diet [15].

In addition to the immediate consequences of infant feeding on growth, body composition, health, and wellness, a number of recent studies have also provided indications that the quantity and quality in the supply of nutrients during childhood has important long-term consequences in the development and function of the organs, health, and risk of disease as well as in the cognitive ability [16]. Human milk is nowadays universally recognized as the optimal feeding choice for every infant [17] where it contains many nutritional components that are able to conserve his development.

The nutritional components of human milk are classified into two categories: macronutrients and micronutrients [18]. Macronutrients of human milk include protein, fat, and sugar. The concentration of human milk macronutrients differed during the course of lactation and between the mothers as well as differed between term and preterm milk. The latter has a higher content of protein and fat. Generally, the mean macronutrient composition of term mature human milk is presented in **Table 1** as compared with cow milk, the most common milk type used in infant formula manufacturing.

**4. The bioactive components of human milk**

milk are discussed.

**4.1. Lactoferrin: for anemia fighting**

**Figure 1.** Protein structure of human Lf. Source: Ref. [41].

Increasing evidence currently shows that short- and long-term benefits of human milk feeding are resulted by its content of various components named functional or bioactive components. These functional components involved a large group of several compounds such as protein (such as lactoferrin (Lf)), carbohydrates (especially human milk oligosaccharides), fats (polyunsaturated fatty acids), vitamins, nucleotides, minerals, and immunoglobulins. In this section, the occurrence, variation, and functionality of selected components of human

Bioactive Components of Human Milk: Similarities and Differences between Human Milk and…

http://dx.doi.org/10.5772/intechopen.73074

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Lactoferrin (Lf) is the second most abundant protein in human milk belonging to the transferrin family [33]. It is a glycoprotein first isolated from cow's milk and second from human milk [34]. It is well known as the principal iron-binding protein in mammals' milk [35] and the first-line defense molecule against infections [33]. The highest content of Lf is found in human colostrum (7 g/L), and this content declined after 2 weeks after birth reaching 2–4 g/L of mature human milk [36]. While Lf content in cow colostrum and milk is 10-fold lower [37]. Structurally, Lf is an iron-binding glycoprotein consisting of a single polypeptide chain distributed to two lobes (N and C lobes). Both human Lf and bovine Lf are sharing a sequence homology of about 70%, and their 3D structures (**Figure 1**) are very similar but not identical [38]. Each lobe of Lf contains an iron-binding site with a high affinity and a glycan-binding site. N and C lobes have very similar conformations but show slight differences in their affin-

ity for iron [39]. **Table 2** presents the differences between human and bovine Lf.

Due to its distribution in several parts of the body and its involvement in several physiological processes, Lf is considered as a multifunctional protein. Moreover, numerous studies have been carried out to uncover the wide range of activities of Lf and its peptides [42, 43]. Iron absorption enhancement by Lf is one of the most observed activities especially in breastfed as compared to formula-fed infants. In this context, the high affinity of Lf to bind iron is a key characteristic of this beneficial role. Although iron is the main cation bound by Lf, other metals such as Cu2+, Zn2+, and Mn2+ ion can be bound by Lf [44]. Lf exists in three forms, according

Proteins provide amino acids for growth as well as are presented in the form of polypeptides that facilitate digestion [19], the defense of the guest [20], and other functions [21]. Fats provide energy, but some have antiviral properties [22]. Carbohydrates provide energy and can also stimulate the absorption of minerals [23], and various human milk oligosaccharides (HMOs) play a pivotal role in the microbial intestinal balance. Energy estimates range from 65 to 70 kcal/dL and are highly correlated with the fat content of human milk. Butte et al. [24] also clearly showed that intakes of energy, protein, fat, and carbohydrate were lower in breastfed than in formula-fed infants at 3 and 6 months. The differences in composition between human milk and infant formulas seem to affect the growth pattern between breastfed infants and formulafed infants [25]. However, no apparent consequences were associated with the lower intake and slower weight gain of breastfed infants where they do not differ in activity level, and they suffer less gastrointestinal and respiratory infections and have higher cognitive development [26].

Because human milk is considered the optimal and first functional food for infant feeding, nowadays, especially in the USA, pasteurized donor milk represents the suitable alternative provided for an infant that is in high risk [28]. However, infant formulas become necessary for infant feeding when human milk is unavailable or the mother cannot breastfeed her infant. So, special efforts are needed to ensure an adequate diet composition in young infants [25].

Various negative consequences are noted with very low- or very high-specific nutrients [29]. For example, cow's milk is not an ideal food during the first year of life. The ingestion of protein for the infants fed with cow's milk is higher than that for those fed with human milk, and this leads to overload renal solutes [30]; in addition, a high-protein intake can cause hypercalciuria [31]. On the other hand, high consumption of cow's milk below the first year of life is one of the most important risk factors for the development of iron deficiency anemia. Cow's milk is low in iron, and much of that iron is attached to the casein micelles, which interferes with its absorption. Additionally, its low content in vitamin C does not favor the absorption of the little iron that contains [32].

Overall, the breastfeeding pattern is the preferred choice of infant nutrition and human milk provides all the nutritional components during 4–6 months of life. It also provides a large group of bioactive components, which play an indispensable role in protecting the infant health.


**Table 1.** Macronutrient concentration of human milk and cow milk.
