Do Probiotics Actually Work?
Quick Answer
For specific conditions, yes. For general "gut health," it's complicated. Probiotics work for antibiotic-associated diarrhea (50% reduction), IBS (modest benefits), and certain infections. But not all strains do the same things. The "throw bacteria at your gut and hope for the best" approach doesn't have strong evidence.
Key Points
- Strain-specific effects: not all probiotics are equal
- Strong evidence for antibiotic diarrhea prevention
- Modest IBS benefits for some people
- Most strains don't permanently colonize
- General "gut health" claims are overstated
Detailed Answer
Probiotics are strain-specific. That's the key insight most marketing ignores. Different strains do different things, and a probiotic that works for diarrhea might do nothing for mood.
WHERE PROBIOTICS ACTUALLY WORK:
• Antibiotic-associated diarrhea: Strong evidence. Saccharomyces boulardii and Lactobacillus rhamnosus GG cut risk by ~50%.
• Infectious diarrhea: Reduces duration by about 1 day. Most effective in children.
• IBS: Modest benefits for some people. Bifidobacterium infantis 35624 has decent data.
• Ulcerative colitis maintenance: VSL#3 has evidence for maintaining remission.
• Vaginal health: Certain Lactobacillus strains help prevent infections.
WHERE EVIDENCE IS WEAK:
• General "gut health" in healthy people • Weight loss • Immune "boosting" • Mood improvement (some promise, but early research) • Eczema prevention (mixed results)
THE COLONIZATION MYTH:
Most probiotic strains don't permanently colonize your gut. They pass through, potentially providing temporary benefits. That's why continuous use is typically needed.
Evidence Quality
Some quality studies, more research helpful
Key Sources:
- reviewProbiotics for Antibiotic-Associated Diarrhea: Cochrane Review
- reviewProbiotics in IBS: Meta-Analysis
- guidelineAGA Clinical Practice Guidelines on Probiotics
Related Questions
Your existing gut microbiome, diet, and the specific strain all matter. Probiotics aren't one-size-fits-all. What works for your friend might not work for you.
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About this information: Our recommendations draw from peer-reviewed clinical trials, systematic reviews, and the same medical databases your doctor uses. These statements have not been evaluated by the FDA. Supplements are not intended to diagnose, treat, cure, or prevent any disease.
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