Supplement analysis backed by scientific evidence · PT

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Moderate evidenceGut health

Lactobacillus Casei

Reclassified into the Lacticaseibacillus genus, this species is best known from drinkable dairy strains (Shirota, DN-114001) with reasonable evidence for antibiotic-associated diarrhea and modest evidence for constipation. Capsule versions of generic "L. casei" are far less studied than the drinks that made it famous.

What the science says

  • Reduces antibiotic-associated diarrhea Moderate evidence

    In a double-blind RCT of 135 hospitalized patients, a fermented milk drink with L. casei DN-114001 plus S. thermophilus and L. bulgaricus twice daily cut antibiotic-associated diarrhea to 12% vs 34% on placebo, and no C. difficile diarrhea occurred in the probiotic group vs 17% on placebo. A separate dose-response RCT of L. casei LBC80R combined with L. acidophilus CL1285 at 100 billion CFU/day found similar protection.

  • Modestly improves functional constipation Limited evidence

    The 2014 meta-analysis of probiotics in adult functional constipation found overall gains of about 1.3 bowel movements per week and improved stool consistency, with the strongest signal for B. lactis; L. casei Shirota trials were among the less consistent contributors and the authors rated the evidence as low quality. Do not expect it to replace fibre or an osmotic laxative.

  • Boosts immunity in healthy people Limited evidence

    Fermented-milk trials report changes in NK cell activity and small reductions in upper respiratory infection days, but effect sizes are small, funding is largely industry, and results are inconsistent across populations. This is not a reason to buy the product.

  • Yogurt drinks are a cost-effective way to take it Moderate evidence

    Most positive trials used the drink format at roughly 6.5-10 billion CFU per bottle, once or twice daily. If you want the studied intervention, the drink is literally what was tested; capsules of generic L. casei are an extrapolation, and the drinks carry 10-15 g sugar per bottle.

Dosage & safety

Studied doseTrials used roughly 6.5-10 billion CFU per serving once or twice daily (fermented milk drinks) or 50-100 billion CFU/day in blended capsules for antibiotic-associated diarrhea prophylaxis. Start on the first day of antibiotics and continue about a week past the course. Constipation trials ran 2-4 weeks.
SafetySafe for most people; gas and bloating are common in the first week. Avoid in the severely immunocompromised, those with central venous lines, short bowel syndrome, or critical illness because of rare bacteremia case reports. Dairy-based drinks contain lactose and added sugar, which matters for people with lactose intolerance or diabetes.

Scientific references

Where to buy

Vitamatic, Lactobacillus Casei, 3.5 oz (100 g)

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