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Head-to-head evidence comparison — which supplement is right for you?
B. lactis (BB-12 / HN019) vs L-Glutamine: L-Glutamine has the stronger overall evidence (6 vs 6/10); 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-Glutamine wins 1 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Too few graded studies
Top outcomes
Verdict
Too few graded studies
1 of 1 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both B. lactis (BB-12 / HN019) and L-Glutamine 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 time of day
Capsule or sachet standardized to a named strain (BB-12 or HN019)
5-10g (a typical label dose, not the dose used in the cited trials, which dosed by body weight at 0.3 to 0.6 g per kg a day)
Post-workout, Before bed, Or split throughout day
L-Glutamine powder
2 weeks
4 weeks
n/a
n/a
Ongoing
2-4 weeks
2-4 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
A Phase 3 Trial of l-Glutamine in Sickle Cell Disease
The New England journal of medicine (2018) · Rct · n=230
A total of 230 patients (age range, 5 to 58 years; 53.9% female) were randomly assigned, in a 2:1 ratio, to receive l-glutamine (152 patients) or placebo (78 patients).
What Is the Role of Nutritional Supplements in Support of Total Hip Replacement and Total Knee Replacement Surgeries? A Systematic Review
Nutrients (2018) · Systematic review
Amino acid supplementation is reported to reduce muscle atrophy and accelerate return of functional mobility.
Evidence and gaps in clinical outcomes of novel pharmacologic therapies for sickle cell disease: A systematic literature review highlighting insights from clinical trials and real-world studies
Blood reviews (2025) · Systematic review · n=97
A pivotal phase III study of l-glutamine showed that patients treated with l-glutamine had a 25 % reduction in pain crises and 33 % fewer hospital days compared to placebo. l-glutamine was generally well tolerated with minimal side effects.
L-Glutamine has a higher evidence score (6/10 vs 6/10) and wins in 1 of 3 categories.
For improve digestion, L-Glutamine has a higher relevance score (80 vs 68).
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.