Human milk vs. cow's milk and the evolution of infant formulas.

Until the early 20th century, a wet nurse was the only safe alternative to breastfeeding, one reason being that each species has a unique composition of its milk. When techniques for chemical analyses of milks and assessment of the energy requirements of infants became available during the 19th century, reasonably safe breast milk substitutes started to be developed. Successively, these were developed into modern infant formulas during the 20th century using human milk composition as reference and cow's milk as protein source. Even with a composition similar to human milk there are differences in performance between formula-fed and breastfed infants. Novel ingredients and new techniques within the dairy industry will contribute to minimize these differences and so might techniques in molecular biology allowing large scale production of recombinant human milk proteins. This technique may be used for production of bioactive substances present in low concentrations in human milk but absent from bovine milk with proven effect on nutrient utilization or other health benefits. For formulas containing novel ingredients with potent biological activities produced with new techniques it will be extremely important that their safety and efficacy are rigorously evaluated because 'functional effects' are not necessarily the same as health benefits.