Limited evidenceGut health

Bacillus Subtilis

A soil-derived spore probiotic, usually sold as DE111. It demonstrably survives and germinates in the small intestine, but the clinical trials behind it are small and mostly report surrogate outcomes.

Evidence last reviewed: August 2026

What the science says

Survival and germination in the gut Moderate evidence
A randomized, crossover, double-blind, placebo-controlled study using intestinal sampling showed that B. subtilis DE111 spores reach the small intestine and germinate there. This establishes plausibility, not clinical benefit.
Bowel habit and immune markers Limited evidence
A randomized study of DE111 in healthy adults found small changes in stool consistency and immune measures, without convincing symptomatic benefit.
Blood lipids and endothelial function Limited evidence
A small randomized study reported that DE111 intake may improve blood lipids and endothelial function in healthy adults; the authors themselves frame it as preliminary.

Dosage & safety

Studied doseTrials used about 1 billion CFU per day of DE111. Products range from 1–5 billion CFU.

SafetyGenerally well tolerated in trials. Bacillus species are opportunistic pathogens in rare cases: avoid in severe immunosuppression, critical illness or with central venous catheters. Spore probiotics are sometimes blamed for bloating in people with SIBO, though this is not well studied.

Scientific references

Presence and Germination of the Probiotic Bacillus subtilis DE111(®) in the Human Small Intestinal Tract: A Randomized, Crossover, Double-Blind, and Placebo-Controlled Study
Colom J, Freitas D, Simon A, Brodkorb A, Buckley M, Deaton J, Winger AM — Front Microbiol, 2021
Examining the Gastrointestinal and Immunomodulatory Effects of the Novel Probiotic Bacillus subtilis DE111
Freedman KE, Hill JL, Wei Y, Vazquez AR, Grubb DS, Trotter RE, Wrigley SD, Johnson SA, Foster MT, Weir TL — Int J Mol Sci, 2021
Bacillus subtilis DE111 intake may improve blood lipids and endothelial function in healthy adults
Trotter RE, Vazquez AR, Grubb DS, Freedman KE, Grabos LE, Jones S, Gentile CL, Melby CL, Johnson SA, Weir TL — Benef Microbes, 2020

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