Research

Mixed

Probiotic supplementation does not significantly alter the overall composition, alpha-diversity, or richness of the fecal microbiota in healthy adults compared to placebo.

If you are healthy, taking probiotics is unlikely to change your gut bacteria composition or diversity. The marketing promise of 'rebalancing' the microbiota in healthy individuals is not supported by current high-quality evidence. Focus on dietary fiber and overall diet quality for microbiota health instead.

GoodRefutesHIGH confidence
This systematic review of the pertinent literature demonstrates a lack of evidence for an impact of probiotics on fecal microbiota composition in healthy adults.
Nadja B. Kristensen et al. · Genome Medicine · 2016

Why this rating

Systematic review of 7 RCTs with medium-to-high quality, though heterogeneity in methods limits meta-analysis.

Source

Alterations in fecal microbiota composition by probiotic supplementation in healthy adults: a systematic review of randomized controlled trials

Nadja B. Kristensen et al. · Genome Medicine · 2016

DOI 10.1186/s13073-016-0300-5

systematic_reviewCited 553×
Read the paper
DOI resolved against Crossref · corpus check 2026-06-10

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