Human milk substitutes. An American perspective.

Formula is a substitute for the preferred nutritional fluid for infants, human milk. Considering that human milk is uniquely suited for human infants, formula feeds have done remarkably well in promoting growth and development of bottle-fed and partially breast-fed infants. Early in the last century, the horrendously high infant mortality rate spurred the development of infant formula. A clean source of milk was thought to be necessary to overcome the mainly diarrheal deaths due to unhygienic conditions. Initially, the success of a formula was measured merely by the survival of the infant. As formulas more closely mimicked the performance of human milk, feedings were compared by the ability to support growth. Now, the additions and alterations to formulas have become more sophisticated and the outcome measures may be protection from infections, visual acuity and mental development. Studies to test these outcomes are difficult and often long term. Additionally, mere growth is recognized as an insufficient measure, rather quality of growth needs to be considered. Formula, like no other food, is potentially the sole source of an individual's nutrition for 4 to 6 months of life. In recognition of its importance, formula is the only food that is regulated by its own law in the United States, the Infant Formula Act of 1986. For the future, breast feeding will remain preferable for almost all infants and breastfeeding should be encouraged. Formulas will continue to be used and will continue to be needed. Improving and assuring the adequacy and safety of infant formulas is an increasingly difficult challenge.