Advantages and disadvantages of soy formulas as alternative to milk have been reviewed by the American Academy of Pediatrics (AAP).

Strongly recommending human milk as the ideal source of nutrition for infant feeding, the AAP Committee on Nutrition reviewed the limited indications and contraindications of soy formulas as well as the potential harmful effects of soy protein-based formulas and the phytoestrogens they contain.

In summary, specific clinical recommendations and findings are as follows:

• Isolated soy protein-based formulas may be used to provide nutrition for normal growth and development in term infants. However, there are few indications to use them instead of formula based on cow's milk. These indications include feeding of infants with galactosemia and hereditary lactase deficiency, which is rare, and in situations in which a vegetarian diet is preferred.
• Extensively hydrolyzed protein formula should be considered for infants with documented cow's milk protein allergy because 10% to 14% of these infants also have soy protein allergy.
• After rehydration, most infants with acute gastroenteritis who were previously well can be managed with continued use of human milk or standard dilutions of cow's milk-based formulas. When secondary lactose intolerance occurs, isolated soy protein-based formulas may be indicated.
• Unless the infant has 1 of the above indications, isolated soy protein-based formula has no advantage over cow's milk protein-based formula as a supplement for the breast-fed infant.
• Soy protein-based formulas are not designed for or recommended for feeding of preterm infants.
• For the prevention or management of infantile colic or fussiness, the routine use of isolated soy protein-based formula is of no demonstrated value.
• Infants who have documented enteropathy or enterocolitis induced by cow's milk protein frequently are as sensitive to soy protein and should therefore be given formula derived from hydrolyzed protein or synthetic amino acids rather than isolated soy protein-based formula. Severe gastrointestinal tract reactions to soy protein-based formula may include enteropathy, enterocolitis, proctitis, small-bowel injury, a reversible celiac-like villus injury that produces an enteropathy with malabsorption, hypoalbuminemia, and failure to thrive.
• For the prevention of atopic disease in healthy or high-risk infants, routine use of isolated soy protein-based formula is of no demonstrated value.

Source: J. Bhatia, F. Greer, and the Committee on Nutrition. Use of Soy Protein-Based Formulas in Infant Feeding Pediatrics 2008;121(5):1062-1068