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Head-to-head evidence comparison — which supplement is right for you?
L. casei Shirota vs L. reuteri DSM 17938: L. reuteri DSM 17938 has the stronger overall evidence (6 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. reuteri DSM 17938 wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Too few graded studies
Top outcomes
Verdict
Mostly mechanism / observational
Top outcomes
Shared outcomes (1)
Outcomes where both L. casei Shirota and L. reuteri DSM 17938 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 time of day
Fermented milk drink containing L. casei Shirota (Yakult), 65-100 mL daily
1 x 10^8 CFU daily (5 drops) for infant colic — the dose used in every positive trial
Any time of day
Oil-suspension drops standardized to DSM 17938
4 weeks
2 weeks
2-12 weeks
8 weeks
1-3 weeks
n/a
1-3 days
4 weeks
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)
Lactobacillus reuteri to Treat Infant Colic: A Meta-analysis.
Pediatrics (2018) · Meta analysis
Day-21 adjusted mean difference in cry/fuss time: -25.4 min/day (95% CI -47.3 to -3.5)
Treating infant colic with the probiotic Lactobacillus reuteri: double blind, placebo controlled randomised trial.
BMJ (2014) · Rct · n=167
Probiotic group cried/fussed 49 minutes MORE than placebo at 1 month (95% CI 8 to 90, P=0.02)
Probiotics to prevent infantile colic.
Cochrane Database Syst Rev (2019) · Meta analysis
No difference in new cases of colic: RR 0.46 (95% CI 0.18-1.19), low certainty
L. reuteri DSM 17938 has a higher evidence score (6/10 vs 5/10) and wins in 2 of 3 categories.
For improve digestion, L. reuteri DSM 17938 has a higher relevance score (55 vs 52).
No documented interaction was found in the data searched. This does not establish that this exact combination is safe.
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.