It is becoming increasingly common for infants to be fed using infant formulas. These formulas are developed scientifically to allow adequate nutrition to infants as they grow. However, they are commercial products and are therefore possess compromises that could be considered to detract from the overall quality. Generally infant formula milk is successful at allowing growth and development of healthy human beings. Most people who have been fed on infant formulas appear healthy and happy as adults. However, the definition of true health is more specific than the broad definition given by the laymen or medical practitioner. In this regard, formula milk has been criticised nutritionally for falling short in a number of areas in comparison to human milk. Evidence in the nutritional literature suggests that human breast milk is a superior food in comparison to cow’s milk based formulas for the growth of human beings. This relates to the presence of a number of factors that are not present in cow’s milk.
The most important of the components present in human milk but absent from cow's milk formulas is docosahexaenoic acid (DHA). Docosahexaenoic acid is a long chain polyunsaturated fatty acid required for the correct development of the brain and central nervous system. Increasingly it is being shown that exposure of the foetus and growing infant to DHA is required for the optimal development of the brain. Further certain cognitive aspects of breast fed infants appear to be superior to those who were fed cow’s milk formulas. Analysis of the function of DHA in humans shows that the fatty acid preferentially accumulates in the brain tissue, where it appears to be required to form a number of docosanoids that are required for neuronal function and neuronal health. The polyunsaturated fatty acids in human milk therefore appear to have beneficial neurological effects. These fats are not present in cow’s milk based formulas because they quickly go rancid following processing, and as such are removed from the milk.
Another factor that may make human milk superior to cow’s milk for infants is the presence of particular growth factors within the milk. Both human and cow’s milk contain growth factors that act as prebiotic foods that stimulate the growth of particular bacteria. However, whilst the growth factors in cow's milk stimulate Bifidobacteria species relevant to cow’s health, the growth factor in human milk stimulate Bifidobacteria species relevant to human health. Further, pasteurisation and freeze-drying destroy the activity of these factors and so although cow’s milk possesses growth factors they do not survive to the formula milk. Breast milk on the other hand is fresh and unpasteurised so that it is able to stimulate the growth of potentially beneficial bacteria that may be required for the correct development of the immune system in the growing infant. This may explain the protective effect of breast milk against the development of particular Western diseases in humans that may develop later in adult life.