How Does Soy Formula Cause Constipation?

Some parents report that soy milk causes constipation in babies.

Soy Formulas

The first American baby to try soy formula did so in 1965 when Enfamil marketed a new soy-based formula called Enfamil Prosobee. Since then, soy formula has grown in popularity so much that it now represents 25 percent of formula sales in North America, with about 15 percent of all North American babies drinking soy. Soy formula was introduced as an alternative to breast milk for mothers who cannot or do not wish to breastfeed and as an alternative to dairy-based formula for babies who seemingly cannot tolerate dairy.

Soy Formula and Constipation

Soy formula is a soy protein isolate made from soybeans. It also contains carrageenan, water, cornstarch, cornstarch hydrolysate and tapioca starch; lactose-free soy formula uses sucrose instead of lactose. In some cases, parents have reported that their babies became constipated as a result of consuming soy formula. According to Encarta Online Dictionary, constipation is "a condition in which a person or animal has difficulty in eliminating solid waste from the body and the feces are hard and dry." Constipation, however, is often misdiagnosed as infrequent passing of solid waste when it actually refers to the consistency of the waste itself.

Constipation in Infants

Constipation in infants is usually due to an abundance of residue left over in the colon after digestion. Breast milk is almost completely absorbed by a baby and leaves no residue. Formula, on the other hand, is less easily digested by a baby and leaves behind more residue in the colon. Because soybeans do produce firmer stool, the soy formula may cause constipation more frequently than dairy formula; however, the constipation is not necessarily the result of soy formula specifically. The constipation could simply be caused by a switch in formulas in general. In addition, children with an allergy specifically to the proteins in milk can be cured of constipation when given soy formula. A 1998 study done by the American Academy of Pediatrics concluded that "healthy full-term infants should be given soy formula only when medically necessary, but soy formula is still safe and effective when needed."

Resources

• Childbirth Solutions: Choosing the Right Infant Formula for Your Baby