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Head-to-head evidence comparison — which supplement is right for you?
B. lactis (BB-12 / HN019) vs L. casei Shirota: B. lactis (BB-12 / HN019) 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.
B. lactis (BB-12 / HN019) wins 2 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 B. lactis (BB-12 / HN019) and L. casei Shirota have evidence — compare verdict strength side-by-side.
1-10 billion CFU daily for BB-12 (1 billion is enough); 10-20 billion CFU daily for HN019 if transit is the goal
any
Capsule or sachet standardized to a named strain (BB-12 or HN019)
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
For stool frequency specifically, B. lactis is the better-evidenced choice. No interaction between them.
Listed for comparison rather than for stacking — no trial has combined them.
2 weeks
4 weeks
n/a
n/a
4 weeks
2 weeks
2-12 weeks
8 weeks
Dose-response effect of Bifidobacterium lactis HN019 on whole gut transit time and functional gastrointestinal symptoms in adults.
Scand J Gastroenterol (2011) · Rct · n=100
Whole-gut transit fell 49 to 21 hours on high dose (p<0.001) and 60 to 41 hours on low dose (p=0.01); placebo unchanged
Eight-Week Supplementation With Bifidobacterium lactis HN019 and Functional Constipation: A Randomized Clinical Trial.
JAMA Netw Open (2024) · Rct · n=229
Primary outcome (change in complete spontaneous bowel movements per week): +0.80 with HN019 vs +0.66 placebo — no difference
Effects of 28-day Bifidobacterium animalis subsp. lactis HN019 supplementation on colonic transit time and gastrointestinal symptoms in adults with functional constipation: A double-blind, randomized, placebo-controlled, and dose-ranging trial.
Gut Microbes (2018) · Rct · n=228
No significant differences vs placebo in the primary outcome (colonic transit time) or any secondary outcome
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)
B. lactis (BB-12 / HN019) has a higher evidence score (6/10 vs 5/10) and wins in 2 of 3 categories.
For improve digestion, B. lactis (BB-12 / HN019) has a higher relevance score (68 vs 52).
For stool frequency specifically, B. lactis is the better-evidenced choice. No interaction between them. Listed for comparison rather than for stacking — no trial has combined them. Consult a healthcare provider for personalized advice.
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.