Can Probiotic Dietary Supplements Prevent Travelers Diarrhea?

The problem: From 5 percent to 50 percent of travelers get hit by diarrhea after being exposed to bacteria their immune system hasn’t seen before.

What may help: Saccharomyces boulardii.


The evidence: “It’s pretty modest,” notes the University of Washington’s Lynne McFarland. (She was scientific director for the company that manufactures the S. boulardii supplement Florastor from 1988 to 2001.) In the two biggest studies, researchers gave 5 billion to 20 billion live S. boulardii cells or a placebo to 3,039 Austrian tourists every day for three weeks, starting five days before they traveled to the tropics, North Africa, the Middle East, or the Far East.

Six of every 15 tourists who took the placebo reported getting diarrhea while they were away, compared with five of every 15 who took the yeast. And the researchers weren’t even certain about that slight benefit, since only about a third of the participants completed the study.

“Tourists are probably the worst subjects for a clinical trial,” explains McFarland. “You’re more interested in having fun, you’re trying new foods, and you don’t exactly take every dose you’re supposed to.”

The bottom line: Don’t count on Saccharomyces boulardii—or any other probiotic—to shield you from travelers diarrhea.

Source: Travel Med. Infect. Dis. 5: 97, 2007.

Travelers Diarrhea Probiotics doesn’t accept any paid advertising or corporate or government funding. Any products recommended by have been vetted by our staff of nutritionists and are not advertisements by the manufacturers.

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