Chronic diarrhea and soy formulas. Inhibition of diarrhea by lactose.

Soy protein formulas are often poorly tolerated by infants with chronic nonspecific or postinfectious diarrhea syndrome. We found that these adverse responses may be prevented by using lactose, instead of sucrose or dextrimaltose, in soy formula. We studied 40 infants diagnosed as soy intolerant. They were given soy formula with differing carbohydrate contents in a randomized, blinded prospective study. Stool output, stool sodium content, and symptoms were significantly improved in infants receiving a soy-lactose formula; no difference was seen in formulas with sucrose or maltose. Improvement occurred in three to five days in most infants. Furthermore, the characteristic frequency distribution of the favorable response to lactose suggested a specific mechanism for the inhibition of water and electrolyte losses through the bowel. The results indicate that, in the absence of lactose intolerance, a soy-lactose formula could be useful in treating chronic diarrhea and secondary protein intolerance.