Bifidobacterium lactis

Bifidobacterium animalis subsp. lactis · B. lactis

Snapshot

Indications	Contraindications
Gut transit time¹ Gut transit time and GI symptoms¹ Irritable bowel syndrome^{2, 3} Digestive comfort^{4, 5} Seasonal allergic rhinitis symptoms⁶ Gut transit and functional GI symptoms¹	Immune-compromised conditions⁷ Milk allergy⁸

Bifidobacterium animalis subsp. lactis is a probiotic bacterium that transiently colonizes the gut and shifts microbiota composition and mucosal immune signaling.² Supplementation is used for gut transit and functional gastrointestinal symptoms, including constipation and irritable bowel syndrome^{1–3, 9}. Trials also cover allergic rhinitis, formula-fed infants, and body fat in obese women. Typical patients are adults with constipation, bloating, or irritable bowel symptoms, and effects are strain-specific.

Results split by strain. One strain shortened whole gut transit time in adults with functional symptoms, while another showed no benefit over placebo in chronic constipation and a fermented milk strain did not beat control in constipated children. A further strain reduced pain in irritable bowel syndrome, with the clearest separation from placebo at follow-up². In patients with coronary artery disease, a 2022 randomized trial found strain Probio-M8 added to statin and beta-blocker therapy improved angina questionnaire scores, with no replication yet¹⁰. Products listing Bifidobacterium lactis number 3791 in the National Institutes of Health label database, mostly as capsules and powders, with fermented milk and infant formula also studied; see Form comparison.

Health Canada lists immune-compromised conditions, including acquired immunodeficiency syndrome, lymphoma, and long-term corticosteroid treatment, as a contraindication⁷. United States product labels ask for physician consultation in pregnancy, nursing, or immune-suppressing medication use⁸.

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

61 sources, 47 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources