Side Effects of Soy Infant Formula

Several significant digestive and intestinal side effects have been reported in infants being fed soy formula. While most babies will tolerate soy-based formulas well, bloating, nausea and constipation are not uncommon. More serious side effects of soy formula on the gut and bowel include vomiting, diarrhea and intestinal bleeding.

Many infants who do not tolerate dairy proteins also have difficulties with soy protein. Side effects and symptoms may include the digestive issues mentioned above, colicky behavior or skin irritation. If your baby is experiencing these side effects after starting soy formula, you may need to consult your pediatrician about hypoallergenic formula options.

The most worrisome side effects potentially associated with soy formula are hormonal ones. Soy contains compounds called genisteins. These compounds act in the body to mimic the effect of estrogen. Studies in lab animals have shown decreased fertility, stunted growth and genital abnormalities linked to the high consumption of soy protein. Studies in humans are inconclusive; however, researchers encourage parents to only opt for soy formula when baby truly cannot tolerate dairy.