Fats(also called lipids) are a key component of infants’ and children’s diets andare particularly important during the first years of life. Fat has an important role in providing energy for the body’s functions, needs and growth. Breastmilk, which provides integral nutrition during babies’ first 6 months of life, contains around 4g of fat per 100 ml. The primary lipids found in breastmilk are triglycerides which make up approximately 98% of breast milk fat. These lipids provide essential fatty acids – both saturated and unsaturated – that our bodies cannot produce otherwise.
The saturated and monounsaturated fatty acids in breast milk fat provide around 40 to 60% of newborns’ energy needs in the first 6 months. These dietary fats are essential for body growth since they act as lipid building blocks for all cells in our bodies. Therefore, they are necessary for the growth and development of all organs and tissues, including skin and hair. Fat is also crucial during infancy and childhood to ensure optimal brain function and healthy development, as it is a major constituent of the nervous system and brain. Furthermore, fat plays an essential role in our intestine, first to assist the digestion ofkey nutrients like vitamins, to support intestinal development, and foster the establishment of a healthy gutmicrobiome and intestinal immune system.
The European Food Safety Authority reviewed the dietary fat requirements and established that just after birth, babies need to get 40% of their energy from fats. With the introduction of complementary feeding, fat intake can gradually be reduced to 20-35% of energy from 4 years old onwards.
Human milk lipid content and composition vary greatly with the mother’s diet. An exclusively vegetarian mother will have milk richer in Omega 6 fatty acids (for example, linoleic acidor LA), whereas Eskimo women, who mainly consume marine foods, will produce milk richer in Omega 3 fatty acids (for example, alpha-linolenic or ALA, eicosapentaenoicor EPA and docosahexaenoic or DHA).
It is known that about 75% of linoleic acid in breast milk comes directly fromthe mother’s diet, and about 30% is derived from the mother’s body’s fat stores which changes during lactation. Another major lipid component of human milk-medium-chain fatty acids (MCFAs) – is also strongly influenced by the number of carbohydrates and fat in the maternal diet.
Dietary fat plays a key role in keeping our body healthy and functioning well. For instance, they are critical to producing various signaling and regulating molecules– like hormones.
During infancy, the composition and structure of fat in breast milk favour its digestion and promote babies’ gut development.
Fats are essential for our body to digest and absorb key micronutrients. For instance, several vitamins required for healthy growth and development are fat-soluble; for example, vitamins A, D, E and K, which our body cannot absorb unless we consume fats.
Some fatty acids in breast milk fat play an important role in absorbing other fats and minerals. For instance, palmitic acid -a major saturated fatty acid in breast milk that represents around 20 to 25 % of breast milk fatty acids- strongly influences the absorption of calcium, which is essential for healthy bone growth and development.
Breast milk lipids are also associated with babies’ health outcomes, for example, they regulate inflammation and increase resistance to infections. This protective benefit is mediated by their essential role in intestinal development, the establishment of the gut microbiome, and the intestinal immune system. Breast milk lipids are complex, and some of them are important modulators of intestinal development and protection against intestinal injury in early life. By acting like building blocks and information messengers in the intestine, milk lipids are key to maintaining intestinal integrity – which refers to the intestine’s unique ability to allow essential nutrients and water to enter our body, while blocking pathogens or toxins.
Finally, breast milk fat composition provides fertile ground for establishing and growing a healthy gut microbiota in early life, which is critical for immune development and protection against infection and allergy. There is emerging evidence that the composition of human milk in milk fat globule and saturated fat influences the composition of infant microbiota such as Bifidobacteria and Lactobacilli, which are necessary for immunity and intestinal protection.
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