CORRECT: Kefir won't stop diarrhea in many kids

NEW YORK (Reuters Health) - If you give your kids kefir to prevent the diarrhea they often get when they take antibiotics, here's some news for you: if your kids are otherwise healthy, it probably won't help, according to a new study.

Up to 35 percent of children who take antibiotics develop diarrhea, according to Dr. Daniel J. Merenstein at George Washington University Medical Center in Washington, DC and colleagues, who performed the study. Sometimes the diarrhea is so severe that the children can't finish taking the medication.

Many sources report that kefir helps prevent antibiotic-associated diarrhea. Kefir, a cultured dairy beverage that's a bit like drinkable yogurt, is rich with probiotics -- bacteria present naturally in the body and sometimes added to food or dietary supplements to boost immune function.

While antibiotics cause diarrhea by disturbing helpful bacteria that live in the intestines, kefir supposedly helps prevent antibiotic-associated diarrhea by stabilizing intestinal populations of healthy bacteria - or so it's been suggested.

Merenstein told Reuters Health that his team's specialty is uncovering the truth behind promises of health benefits attributed to popular products. This time, they studied Probugs, a kefir product for children sold in supermarkets across the U.S.

(The study was funded by Lifeway Foods, which manufactures Probugs. On its website, Lifeway claims that its kefir is "far more probiotic than yogurt, with 10 live cultures that work in your body to help build immunity, improve digestion, fight off disease, and so much more.")

The researchers tested Probugs in a carefully controlled study that involved 125 children between the ages of 1 and 5 whose doctors had prescribed antibiotics for various reasons. For 10 days, while the children were taking the antibiotics, they also drank the kefir - but for half the children, the kefir had been heated in advance to kill off the probiotics.

No one - not the children, their parents, or the doctors and nurses involved in the study - knew which children were drinking the real kefir and which were drinking the inactivated substitute.

Overall, "there were no differences in the rates of diarrhea" between the two groups, the investigators report in the Archives of Pediatric and Adolescent Medicine. Furthermore, the real kefir did not provide any benefit in terms of stomach pain, vomiting, fever, irritability, lethargy, missed school days, or a variety of other factors.

The study did yield "some intriguing data" that may yet "hold promise for kefir's role in antibiotic-associated diarrhea," the researchers said. In children between the ages of 3 and 5, for example, Probugs did help prevent diarrhea, with more diarrhea among the children who drank the fake product.

Also, boys who drank the fake product had 25 percent more diarrhea than boys who drank the real kefir. There was no such difference in girls, however.

Finally, the Probugs kefir did a better job at preventing diarrhea in the subset of children whose health was poorer to begin with.

"Our theory is that kefir may not have helped healthy children (in our study) that much because the extra immune system boost provided by the drink may not (have been) necessary" for them, Merenstein said in a prepared statement.

"We had a really healthy patient population" overall, Merenstein told Reuters Health, adding that in less affluent regions where children's health is poor, kefir might provide a much more substantial benefit in preventing diarrhea.

So if it's not preventing diarrhea in healthy kids to any significant extent, does drinking kefir actually confer any benefit for them at all, or would they be just as well off drinking milk?

"That is an interesting question," Merenstein said. "Kefir, like most yogurts, is a very healthy snack that provides protein, calcium and vitamin D."

"But," he added, "so does milk....I would say that kefir is a healthy alternative for kids that won't drink milk, or a very healthy snack."

"It may not prevent diarrhea in kids on antibiotics," he concluded, "but further studies need to be conducted."

SOURCE: Archives of Pediatric & Adolescent Medicine, August 2009.