Soy formula shouldn't be your first choice when choosing what to feed baby, but it is safe and may be right for some babies.
Concerns over soy formula stem from the fact that soybeans and other legumes contain a small amount of natural estrogen, which, since it's a hormone, could in theory affect a child's reproductive organs and maturation. Studies done on lab rats and monkeys that were fed soy or components of soy have found some adverse affects, but a recent National Institutes of Health report concluded there's no evidence that feeding soy formula to babies leads to reproductive problems.
The American Academy of Pediatrics (AAP) says that when breastfeeding isn't possible, then parents should give infants formula made from cow's milk, and they should only offer soy formula when special situations exist. For instance, soy formula is fed to babies with galactosemia (a rare metabolic disorder) who can't consume milk with the sugars lactose or galactose. And it can be given to a child with a confirmed milk allergy who isn't also allergic to soy (though many babies are allergic to both). The AAP also says a strict vegetarian who doesn't breastfeed can use soy formula -- as long as the infant isn't preterm. --Gina Bevinetto Feld
Originally published in American Baby magazine, October 2007. Updated 2009.