Nutritional aspects of soy formula.

Soy formula is a commonly used alternative to cows' milk formula. While its primary use has been for infants with milk protein allergy and lactose intolerance, soy formula is used increasingly for infants with gastrointestinal discomfort. The nutritional composition of soy formula has been designed to cover the nutrient needs of the newborn infant; however, some aspects of its composition need further consideration. The protein level of soy formula is usually higher than that of milk-based formulae, partially because of differences in protein digestibility and partly because of differences in amino acid composition. The presence of phytic acid in soy formula presents a problem with regard to mineral and trace element bioavailability. Several steps can be taken to minimize this problem, either by reducing the phytate content of soy protein isolate or by changing levels of minerals/trace elements in the formula. Finally, the high levels of manganese in soy formula present a potential problem in that manganese absorption and retention are high during infancy.