Supplement encyclopedia

Bacillus subtilis

Name: Bacillus subtilis
Creator: Pillintrip Editorial Team

Written by Pillintrip Editorial Team Updated October 30, 2026

Bacillus subtilis is a spore-forming bacterium used in some food starter cultures and supplements. This page covers specific strains and everyday goals in adults, without disease-treatment claims.

Double-check the conclusions and read the sources before choosing a supplement.

Main conclusion

Possible benefits

BS50 shows a preliminary signal of relief in combined mild digestive discomfort. Overall comparisons with MB40 and R0179 did not show similar improvement. The described trials did not demonstrate clear improvements in sleep quality, normal bowel habits or days with cold-like symptoms. Choose a product by its exact strain. [1] [2] [3] [4]

What was studied

Live BS50, MB40, R0179 and CU1: four independent studies. Three BS50 rows describe different outcomes in one cohort and must not be counted as separate trials. [1] [2] [3] [4]

Food sources

Effects and studied questions

Goal or question	Result	Confidence	Studies	Population studied	Key sources
Digestive discomfort: BS50	BS50 may be considered for mild digestive discomfort; the result concerns this strain and the combined scale.A reduction of at least two points in the combined bloating, burping and gas score occurred in 47.4% versus 22.2% with placebo, a difference of about 25 percentage points; odds ratio 3.2 (95% CI 1.1–8.7). This is the proportion of participants whose score changed, not the percentage reduction in symptoms. Gas alone did not differ significantly.	2/5	1One named direct randomized controlled trial; repeated BS50 outcomes concern the same 76 participants.The probiotic Bacillus subtilis BS50 decreases gastrointestinal symptoms in healthy adults: a randomized, double-blind, placebo-controlled trial ↗	76 healthy adults aged 30–65 with mild gas, bloating or burping; all completed the trial, with 74 in the per-protocol analysis	The probiotic Bacillus subtilis BS50 decreases gastrointestinal symptoms in healthy adults: a randomized, double-blind, placebo-controlled trial ↗
Bloating and gas: MB40	This trial does not provide a firm basis for expecting overall relief of bloating with MB40.No significant differences in bloating, pain or gas were found in the overall sample. Positive findings appeared only in men after analysis by sex.	2/5	1One named direct randomized controlled trial; repeated BS50 outcomes concern the same 76 participants.A Randomized, Double-blind, Placebo-controlled, Parallel Study Evaluating the Efficacy of Bacillus subtilis MB40 to Reduce Abdominal Discomfort, Gas, and Bloating ↗	100 healthy adults	A Randomized, Double-blind, Placebo-controlled, Parallel Study Evaluating the Efficacy of Bacillus subtilis MB40 to Reduce Abdominal Discomfort, Gas, and Bloating ↗
Digestive well-being: R0179	No convincing advantage of R0179 for noticeable digestive improvement was shown in a similar population.Overall well-being and digestive measures did not improve significantly versus placebo. Increased shedding of spores in stool does not itself mean improved well-being.	2/5	1One named direct randomized controlled trial; repeated BS50 outcomes concern the same 76 participants.Evaluation of Bacillus subtilis R0179 on gastrointestinal viability and general wellness: a randomised, double-blind, placebo-controlled trial in healthy adults ↗	81 healthy adults with mostly mild symptoms at baseline	Evaluation of Bacillus subtilis R0179 on gastrointestinal viability and general wellness: a randomised, double-blind, placebo-controlled trial in healthy adults ↗
Bowel regularity and stool consistency	This trial found no convincing added benefit of BS50 for changing normal bowel habits.Bowel-movement frequency and stool consistency did not differ significantly from placebo: p=0.94 and p=0.29 for differences in change. People with chronic constipation were not specifically recruited.	2/5	1One named direct randomized controlled trial; repeated BS50 outcomes concern the same 76 participants.The probiotic Bacillus subtilis BS50 decreases gastrointestinal symptoms in healthy adults: a randomized, double-blind, placebo-controlled trial ↗	76 healthy adults aged 30–65 with mild gas, bloating or burping; all completed the trial, with 74 in the per-protocol analysis; bowel habits were mostly normal at baseline	The probiotic Bacillus subtilis BS50 decreases gastrointestinal symptoms in healthy adults: a randomized, double-blind, placebo-controlled trial ↗
Days with cold-like symptoms	CU1 did not convincingly reduce days with cold-like symptoms in the full group.Respiratory symptoms: 4.4 versus 6.2 days per person, p=0.1027; at least one episode: 24/50 versus 31/50, p=0.1609. The primary measure of days with respiratory or intestinal symptoms was 5.1 versus 6.6, p=0.2015.	2/5	1One named direct randomized controlled trial; repeated BS50 outcomes concern the same 76 participants.Probiotic strain Bacillus subtilis CU1 stimulates immune system of elderly during common infectious disease period: a randomized, double-blind placebo-controlled study ↗	100 healthy, independently living adults aged 60–74 with a history of recurrent infectious episodes	Probiotic strain Bacillus subtilis CU1 stimulates immune system of elderly during common infectious disease period: a randomized, double-blind placebo-controlled study ↗
Usual sleep quality	BS50 has no confirmed sleep benefit in people with a similar baseline status.Mean self-rated sleep and the proportion reporting good or excellent sleep did not change versus placebo. Before supplementation, more than 75% already reported good or excellent sleep.	1/5	1One named direct randomized controlled trial; repeated BS50 outcomes concern the same 76 participants.The probiotic Bacillus subtilis BS50 decreases gastrointestinal symptoms in healthy adults: a randomized, double-blind, placebo-controlled trial ↗	76 healthy adults aged 30–65 with mild gas, bloating or burping; all completed the trial, with 74 in the per-protocol analysis; mean baseline sleep rating was 7 out of 10	The probiotic Bacillus subtilis BS50 decreases gastrointestinal symptoms in healthy adults: a randomized, double-blind, placebo-controlled trial ↗

The study count refers to the cited source. Reviews with overlapping trials and outcomes from one study are not added together.

Guidance for each goal

Digestive discomfort: BS50

Confidence2/5

BS50 may be considered for mild digestive discomfort; the result concerns this strain and the combined scale.

Study findings. A reduction of at least two points in the combined bloating, burping and gas score occurred in 47.4% versus 22.2% with placebo, a difference of about 25 percentage points; odds ratio 3.2 (95% CI 1.1–8.7). This is the proportion of participants whose score changed, not the percentage reduction in symptoms. Gas alone did not differ significantly.

Studied regimen2 billion CFU once daily with the largest mealLive B. subtilis BS50 spores

Duration and populationSix weeks76 healthy adults aged 30–65 with mild gas, bloating or burping; all completed the trial, with 74 in the per-protocol analysis

Bloating and gas: MB40

Confidence2/5

This trial does not provide a firm basis for expecting overall relief of bloating with MB40.

Study findings. No significant differences in bloating, pain or gas were found in the overall sample. Positive findings appeared only in men after analysis by sex.

Studied regimen5 billion CFU/dayLive B. subtilis MB40 strain

Duration and populationFour weeks100 healthy adults

Digestive well-being: R0179

Confidence2/5

No convincing advantage of R0179 for noticeable digestive improvement was shown in a similar population.

Study findings. Overall well-being and digestive measures did not improve significantly versus placebo. Increased shedding of spores in stool does not itself mean improved well-being.

Studied regimen0.1, 1 or 10 billion CFU/dayLive B. subtilis R0179 strain

Duration and populationFour weeks81 healthy adults with mostly mild symptoms at baseline

Bowel regularity and stool consistency

Confidence2/5

This trial found no convincing added benefit of BS50 for changing normal bowel habits.

Study findings. Bowel-movement frequency and stool consistency did not differ significantly from placebo: p=0.94 and p=0.29 for differences in change. People with chronic constipation were not specifically recruited.

Studied regimen2 billion CFU/dayLive B. subtilis BS50 spores

Duration and populationSix weeks76 healthy adults aged 30–65 with mild gas, bloating or burping; all completed the trial, with 74 in the per-protocol analysis; bowel habits were mostly normal at baseline

Days with cold-like symptoms

Confidence2/5

CU1 did not convincingly reduce days with cold-like symptoms in the full group.

Study findings. Respiratory symptoms: 4.4 versus 6.2 days per person, p=0.1027; at least one episode: 24/50 versus 31/50, p=0.1609. The primary measure of days with respiratory or intestinal symptoms was 5.1 versus 6.6, p=0.2015.

Studied regimen2 billion spores/day on treatment daysLive B. subtilis CU1 spores

Duration and population16 weeks of observation: four cycles of 10 days taking the product and 18 days off100 healthy, independently living adults aged 60–74 with a history of recurrent infectious episodes

Usual sleep quality

Confidence1/5

BS50 has no confirmed sleep benefit in people with a similar baseline status.

Study findings. Mean self-rated sleep and the proportion reporting good or excellent sleep did not change versus placebo. Before supplementation, more than 75% already reported good or excellent sleep.

Studied regimen2 billion CFU/dayLive B. subtilis BS50 spores

Duration and populationSix weeks76 healthy adults aged 30–65 with mild gas, bloating or burping; all completed the trial, with 74 in the per-protocol analysis; mean baseline sleep rating was 7 out of 10

How to read the confidence scale 1–5

The rating considers study quality, directness and applicability to the stated group and regimen. It is an editorial scale, not the probability of an individual result.

Safety and limitations

In a short MB40 trial, 27 of 30 enrolled participants completed follow-up: seven days of placebo, then 21 days of MB40 at 10 billion CFU/day. One participant had vomiting and chills judged probably related to supplementation; the symptoms resolved. No serious reactions were recorded in this small trial. Live microorganisms may pose an additional infection risk in immunodeficiency, severe illness or with a central venous catheter. Premature infants are a separate risk group covered by a specific FDA warning on probiotics. Short studies in healthy adults do not establish safety in pregnancy or breastfeeding. Check the exact strain, live or inactivated form, CFU count at the end of shelf life and storage conditions. Milligram amounts do not replace viable-cell counts.

Safety Assessment of Bacillus subtilis MB40 for Use in Foods and Dietary Supplements ↗ · The probiotic Bacillus subtilis BS50 decreases gastrointestinal symptoms in healthy adults: a randomized, double-blind, placebo-controlled trial ↗ · Probiotics — Health Professional Fact Sheet (NIH ODS) ↗ · FDA Raises Concerns About Probiotic Products Sold for Use in Hospitalized Preterm Infants ↗

Interactions

With	Effect	Action	Source
Antibiotics	They may inhibit susceptible live strains; there is no universal interval for all B. subtilis products.	Check compatibility and dosing conditions for the specific strain against the medicine's instructions.	Probiotics — Health Professional Fact Sheet (NIH ODS) ↗
Vitamin K antagonists and natto	Natto may affect vitamin K intake; this is a property of the food, not a proven interaction of every B. subtilis strain.	Discuss natto intake when taking vitamin K antagonists.	Treatment of natto, a fermented soybean preparation, to prevent excessive plasma vitamin K concentrations in patients taking warfarin ↗

Forms

BS50, MB40, R0179 and CU1: Different live strains; compare the exact code and studied dose, not just the species name. Inactivated products: Nonliving-cell counts are not viable CFU counts; an inactivated product is not equivalent to live spores. DE111: A newer source assigns it to Bacillus inaquosorum. Its sports findings must not be transferred to the current B. subtilis catalogue species. Food starter cultures: Natto and other food strains differ from BS50, MB40, R0179 and CU1. Food fermentation does not establish the same effect as a capsule.

Food sources

B. subtilis participates in fermentation of soy foods such as natto, kinema, cheonggukjang and thua nao, and of some other legumes and seeds. These food cultures contain different strains and are not a direct substitute for the studied capsule. Fresh paste, dried condiments and heated dishes differ in live-cell and spore counts. The word “fermented” alone does not identify the strain in a food. The doses of BS50, MB40, R0179 and CU1 concern the named products and cannot be converted from the portion weight of traditional foods.

Natto — Japan — Fermented soy foods; cooked fermented soybeans. Food strains of B. subtilis natto are used as starters; the finished dish differs from a BS50 capsule., Kinema — Nepal and northeastern India — Fermented soy foods; fermented soybeans or paste. Food strains of B. subtilis have been isolated from studied products., Cheonggukjang — Korea — Fermented soy foods; fermented soybeans or paste. B. subtilis was isolated from this food; cooking heat changes the live culture., Thua nao — Thailand — Fermented soy foods; fresh paste or dried fermented soy sheets. Different B. subtilis strains have been studied in this product; fresh and dried forms are not equivalent in live-cell content., Pepok — Myanmar — Fermented soy foods; fermented soybean paste. One of the regional soy foods from which B. subtilis was isolated and its genomes compared., Mak thua nao — Laos — Fermented soy foods; fermented soybean paste. One of the studied traditional soy foods containing food strains of B. subtilis., Soumbala — Burkina Faso — Other fermented legumes; a condiment from African locust bean seeds, Parkia biglobosa. Food strains of B. subtilis and B. pumilus were genetically identified; fermentation is mixed., Bikalga — Burkina Faso — Fermented seeds; a condiment from fermented Hibiscus sabdariffa seeds. B. subtilis subsp. subtilis was isolated from this food; these are hibiscus seeds, not the flower calyces used for hibiscus tea.

Whole-Genome Sequencing and Comparative Genome Analysis of Bacillus subtilis Strains Isolated from Non-Salted Fermented Soybean Foods ↗

Studies

Publication	What was studied	Participants	Form and dose	Result
The probiotic Bacillus subtilis BS50 decreases gastrointestinal symptoms in healthy adults: a randomized, double-blind, placebo-controlled trial ↗	Digestive discomfort: BS50; Bowel regularity and stool consistency; Usual sleep quality	76 healthy adults aged 30–65 with mild gas, bloating or burping; all completed the trial, with 74 in the per-protocol analysis	Live B. subtilis BS50 spores: 2 billion CFU once daily with the largest meal. Six weeks	A reduction of at least two points in the combined bloating, burping and gas score occurred in 47.4% versus 22.2% with placebo, a difference of about 25 percentage points; odds ratio 3.2 (95% CI 1.1–8.7). This is the proportion of participants whose score changed, not the percentage reduction in symptoms. Gas alone did not differ significantly. Bowel-movement frequency and stool consistency did not differ significantly from placebo: p=0.94 and p=0.29 for differences in change. People with chronic constipation were not specifically recruited. Mean self-rated sleep and the proportion reporting good or excellent sleep did not change versus placebo. Before supplementation, more than 75% already reported good or excellent sleep.
A Randomized, Double-blind, Placebo-controlled, Parallel Study Evaluating the Efficacy of Bacillus subtilis MB40 to Reduce Abdominal Discomfort, Gas, and Bloating ↗	Bloating and gas: MB40	100 healthy adults	Live B. subtilis MB40 strain: 5 billion CFU/day. Four weeks	No significant differences in bloating, pain or gas were found in the overall sample. Positive findings appeared only in men after analysis by sex.
Evaluation of Bacillus subtilis R0179 on gastrointestinal viability and general wellness: a randomised, double-blind, placebo-controlled trial in healthy adults ↗	Digestive well-being: R0179	81 healthy adults with mostly mild symptoms at baseline	Live B. subtilis R0179 strain: 0.1, 1 or 10 billion CFU/day. Four weeks	Overall well-being and digestive measures did not improve significantly versus placebo. Increased shedding of spores in stool does not itself mean improved well-being.
Probiotic strain Bacillus subtilis CU1 stimulates immune system of elderly during common infectious disease period: a randomized, double-blind placebo-controlled study ↗	Days with cold-like symptoms	100 healthy, independently living adults aged 60–74 with a history of recurrent infectious episodes	Live B. subtilis CU1 spores: 2 billion spores/day on treatment days. 16 weeks of observation: four cycles of 10 days taking the product and 18 days off	Respiratory symptoms: 4.4 versus 6.2 days per person, p=0.1027; at least one episode: 24/50 versus 31/50, p=0.1609. The primary measure of days with respiratory or intestinal symptoms was 5.1 versus 6.6, p=0.2015.

Bacillus subtilis

Main conclusion

Possible benefits

What was studied

Food sources

Effects and studied questions

Guidance for each goal

Digestive discomfort: BS50

Bloating and gas: MB40

Digestive well-being: R0179

Bowel regularity and stool consistency

Days with cold-like symptoms

Usual sleep quality

Safety and limitations

Interactions

Forms

Food sources

Studies

Sources