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Head-to-head evidence comparison — which supplement is right for you?
L. casei Shirota vs L. plantarum 299v: L. plantarum 299v has the stronger overall evidence (5 vs 5/10); they're alternatives for improve digestion — the best pick depends on your goals. Take the 60-second quiz for a pick tailored to your goals.
L. plantarum 299v wins 1 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Mostly mechanism / observational
Top outcomes
Verdict
Mostly mechanism / observational
Top outcomes
Shared outcomes (1)
Outcomes where both L. casei Shirota and L. plantarum 299v have evidence — compare verdict strength side-by-side.
One 65-100 mL bottle of the fermented milk drink daily, delivering roughly 6.5 x 10^9 to 1 x 10^11 CFU depending on the product. Doses across trials span this whole range with no dose-comparison study to separate them.
any
Fermented milk drink containing L. casei Shirota (Yakult), 65-100 mL daily
1 x 10^9 CFU (1 billion) daily taken WITH the iron-containing meal is sufficient for the iron effect — in the dual-isotope crossover trial 10^9 was significant (28.6% vs 18.5%, p<0.028) while 10^10 was NOT (29.1% vs 20.1%, p=0.080). The freeze-dried capsule and IBS trials used 1 x 10^10 CFU daily, and the pregnancy trial used 1 x 10^10 CFU twice daily (2 x 10^10 CFU/day)
with-meals
Freeze-dried capsule standardized to 299v (DSM 9843)
4 weeks
2 weeks
2-12 weeks
8 weeks
Immediate, per meal
12-25 weeks
4 weeks
n/a
Efficacy of daily intake of Lactobacillus casei Shirota on respiratory symptoms and influenza vaccination immune response: a randomized, double-blind, placebo-controlled trial in healthy elderly nursing home residents.
Am J Clin Nutr (2012) · Rct · n=737
PRIMARY ENDPOINTS ALL NULL: no effect on days with respiratory symptoms, probability of respiratory symptoms, or post-vaccination antibody titre
Probiotics and synbiotics in chronic constipation in adults: A systematic review and meta-analysis of randomized controlled trials.
Clin Nutr (2022) · Meta analysis
Probiotics overall increased stool frequency (SMD 0.71, 95% CI 0.37-1.04, p<0.00001) — but the effect was driven by Bifidobacterium lactis, 'not mixtures of probiotics, Bacillus coagulans Unique IS2 or Lactobacillus casei Shirota'
A study into the effect of Lactobacillus casei Shirota in preventing antibiotic associated diarrhoea including Clostridioides difficile infection in patients with spinal cord injuries: a multicentre randomised, double-blind, placebo-controlled trial.
EClinicalMedicine (2021) · Rct · n=359
PRIMARY ENDPOINT NULL: antibiotic-associated diarrhoea at 30 days 45% vs 42.1% (RR 1.071, 95% CI 0.8-1.4, p=0.639)
A Systematic Review and Meta-Analysis on the Effects of Probiotic Species on Iron Absorption and Iron Status.
Nutrients (2019) · Meta analysis
Pooled SMD 0.55 (95% CI 0.22-0.88, p=0.001) for increased iron absorption across 8 studies
The effect of Lactiplantibacillus plantarum 299v together with a low dose of iron on iron status in healthy pregnant women: A randomized clinical trial.
Acta Obstet Gynecol Scand (2021) · Rct · n=326
Iron deficiency at week 35: 59% vs 78% (p=0.017); iron-deficiency anaemia 7.4% vs 21% (p=0.023)
Efficacy of Probiotics in Irritable Bowel Syndrome: Systematic Review and Meta-analysis.
Gastroenterology (2023) · Meta analysis
For global IBS symptoms, certainty of evidence was LOW for this strain (moderate only for Escherichia strains)
L. plantarum 299v has a higher evidence score (5/10 vs 5/10) and wins in 1 of 3 categories.
For improve digestion, L. casei Shirota has a higher relevance score (52 vs 50).
No known interactions between L. casei Shirota and L. plantarum 299v have been documented in our database. However, always consult a healthcare provider before combining supplements.
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.