Adverse effects of milk formula ingestion on the gastrointestinal tract. An update

The large-scale use of cow's milk in infant feeding is less than one hundred years old. Much progress has been made by the manufacturers of proprietary formulas during this period to make their products safer. Although the current formulas provide an excellent "substitute" for the majority of infants, problems still remain, and it is necessary for every pediatrician and gastroenterologist to be aware of these. The purposes of this article are to review the adverse effects of nonhuman milk on the gastrointestinal tract, to examine the underlying mechanisms, and hopefully to stimulate further thought and research. Particular emphasis will be placed on hypersensitivity reactions, because there now appears to be a swing back to this diagnosis as a result of more sophisticated immunologic investigations. The arguments in favor of breast-feeding, the systemic biochemical differences resulting from different formulas, and the indications for specialized formula feeding are all beyond the scope of this review.