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Evidence-Based Supplement Research
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Big effect

In kids with acute gastroenteritis, a high-dose probiotic cut persistent watery diarrhea from 58.6% to 19.4% by day 5 — but the trial was set in a hospital emergency department, so the results may not apply to milder cases managed at home.

This is a striking effect in a well-controlled clinical setting, and it adds to a body of 11 randomized trials where most (8) also found benefit, though effect sizes have varied widely — so while the probiotic looks promising for severe pediatric diarrhea, the strength of evidence is not yet uniform across all contexts.

Researchers gave children with acute gastroenteritis either a high dose of Lactobacillus reuteri DSM 17938 or a placebo alongside standard rehydration. By day 5, only 19.4% of the probiotic group still had watery diarrhea, compared to 58.6% in the placebo group — meaning the probiotic roughly tripled the chance of recovery within that window. The caveat is that these were children sick enough to visit an emergency room; it’s unclear if the same benefit would hold in milder, outpatient cases.

Where this fits in the evidence

Pillser has synthesized 11 studies on Lactobacillus reuteri DSM 17938 for Reduced Diarrhea Rate — overall evidence strength: High.

Across 11 studies, 8 reported beneficial effects of Lactobacillus reuteri DSM 17938 on reducing diarrhea rates, with effect sizes ranging from small to large (predominantly small to moderate). The most common dose was around 1-4 × 10^8 CFU/day, and the most studied population was children with acute gastroenteritis or diarrhea. Evidence shows a moderate-sized beneficial effect, particularly in clinical settings with hospitalized or outpatient children.

The study

Lactobacillus reuteri protectis DSM 17938 at high doses versus placebo in children with acute gastroenteritis in a Pediatric Emergency Department.

  • Randomized Controlled Trial (RCT)
  • 2025-03-03
  • Journal of pediatric gastroenterology and nutrition
More on Lactobacillus reuteri DSM 17938More on Reduced Diarrhea Rate

This is a plain-language summary of a research finding, not medical advice. Pillser surfaces research signals to help you decide what's worth investigating — always consult a qualified professional before changing what you take.

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