Human milk contains all the nutrients that a baby needs for growth and development. Breast-fed babies are less likely to suffer from diarrhea, pneumonia, ear infection, meningitis and urinary infection. The risks of developing chronic diseases such as obesity, cardiovascular diseases and allergic diseases in adulthood are also lower in breast-fed babies. These babies also tend to achieve higher intelligence. These benefits are mostly due to the nutrition superiority of human milk compared with animal milks like cow or goat milk.
Human milk contains 4.2 percent fats, which is higher than goat or cow milk. Most of the fats in human milk, goat milk and cow milk are in the form of triglycerides, but they differ in their fatty acid compositions. Human milk has long-chain polyunsaturated fatty acids such as docosahexaenoic acid, or DHA, and arachidonic acid, or ARA, both of which are not found in goat milk or cow milk. DHA and ARA are important components of the nervous system and the eye and are actively taken up by these tissues.
The carbohydrates in milk are primarily lactose. The lactose concentration in human milk is higher than cow milk or goat milk. In addition, human milk is unique in that it contains oligosaccharides, which block bacteria attachment to the intestinal surface and reduce the risk of gastrointestinal infections.
At 0.9 gram per 100 milliliters, human milk contains far less protein than cow or goat milk. However, the proteins in human milk are balanced and easier to digest. This meets the baby’s unique protein requirements while protecting the baby’s immature kidneys from an overload of protein wastes.
Human milk is less allergenic due to the lack of beta-lactoglobulin, an offending protein for babies who are intolerant of cow milk. Human milk, cow and goat milk all contain alpha-lactoalbumin, but with slightly different structures. The lactoalbumin in human milk is best tolerated, but people who are allergic to the lactoalbumin in cow milk may still be able to drink goat milk.
Human milk also contains enzymes, growth factors and immunoglobulins. These are protein molecules that enhance digestion and absorption of nutrients, stimulate growth and development and fight off infections. In addition, breakdown of the human milk protein casein in the baby’s gut produces an opioid-like substance called casomorphin that can influence the baby’s mood and behavior.
Vitamins and Minerals
Human milk has all the necessary vitamins and minerals that are required for the baby’s growth and development, with the exception of vitamin D. Babies need to obtain vitamin D from sun exposure or supplements if they are exclusively breastfed. Compared with human milk, cow milk and goat milk are relatively low in iron and copper. Because the synthesis of red blood cells depends on these two nutrients, consuming cow or goat milk without supplementation can lead to infant anemia. In addition, cow and goat milks may contain too much calcium and phosphorous for the baby's kidneys to handle.
All milks show variation in nutrients with diet, season, lactation stage and the individual. For example, the fatty acids and the water-soluble B and C vitamins in human milk vary with the maternal diet. Supplementation by the mother increases these nutrients in breast milk. Vitamin C content in human milk shows characteristic changes with the seasons, with the highest level observed in summer when vitamin C-rich fruits are abundant. Calcium, fats and proteins can vary by two- to three-fold between individuals. Similarly, cow milk and goat milk show variations with the seasons and animal feeds. Both cow milk and goat milk tend to be more nutritious in the winter and early spring when the early milk colostrum is produced than in the summer when the milk production has run its course. The quality of the feed is known to change the fat composition, the flavor and the quantity of the milk produced.