Benefits
Bloating, gas and abdominal discomfort in adults with frequent bloating
In 100 healthy adults with frequent bloating, 5 billion CFU a day for 4 weeks did not change bloating intensity, bloating days, gas or abdominal discomfort more than placebo in the whole group, and bloating was the main outcome. Larger drops than placebo were reported only in the men, without p-values in the abstract. The maker sponsored the trial and three authors are named as BIO-CAT staff in other papers.
Quality of life scores during a 4 week trial
In the same bloating trial, physical functioning on a quality of life questionnaire was better than placebo at week 2. Physical role limitation, vitality and social functioning improved from the start to week 4 within the probiotic group, which is a before and after change rather than a comparison with placebo. These were secondary measures in a trial whose main outcome was not met.
Staphylococcus aureus carriage in stool and nose
In 115 Thai adults who carried S. aureus, 10 billion CFU a day for 30 days lowered S. aureus counts by about 97 percent in stool and 65 percent in the nose, while placebo counts did not change significantly; the main outcome was met. Researchers bought the product and were funded by Thai and US government grants. Infections were not measured.
Bowel habits and stomach comfort in a 4 week tolerability study
In 30 healthy adults given a placebo for 1 week and then 10 billion CFU a day for 3 weeks, weekly bowel movements stayed about the same and stomach and bowel symptoms were few and mostly mild. Everyone received the probiotic after the placebo week, so this was a safety check rather than a test of benefit. The maker funded and coauthored it.
Immune response to a bacterial challenge in piglets (animal work)
In 32 young piglets, a diet with MB40 for 14 days, with Listeria monocytogenes injected on day 8, left 67 percent fewer Listeria bacteria in the liver and 49 percent fewer in the spleen than the plain diet, and fewer blood monocytes. This was an animal study funded by the maker and has not been tested in people.
Mechanism of action
Fengycins and S. aureus signaling
Bacillus bacteria make fengycins, lipopeptides that blocked the quorum-sensing signal S. aureus needs to colonize the mouse gut, in work that also found no S. aureus in Thai villagers whose stool held Bacillus. Researchers picked MB40 for their human trial because it made more fengycins than other commercial B. subtilis strains they tested.
Spore passage through the gut
MB40 is taken as dormant spores. After 30 days of 10 billion CFU a day, all treated participants had Bacillus in stool at about 1,000 to 100,000 CFU per gram, identified as B. subtilis, and none in the nose. The overall makeup of the gut microbiota did not change significantly, which the authors read as a targeted effect.
Immune markers in an animal infection model
In piglets injected with Listeria, MB40 in the diet lowered bacterial counts in the liver and spleen and was linked to fewer circulating monocytes. How MB40 might act on the immune system in people has not been measured.
Clinical trials
Randomized, double-blind, placebo-controlled parallel trial at sites in California, Florida and Ontario, with KGK Science as collaborator; 5 billion CFU MB40 or placebo once daily for 4 weeks; registered NCT02950012 with weekly mean daily bloating score as the primary outcome; sponsored by BIO-CAT Microbials; Penet, Kramer and Spears are named as BIO-CAT employees in other MB40 papers (Penet et al. 2021, Altern Ther Health Med)
100 healthy adults (50 per group) with frequent bloating at screening and during a run-in period.
Null primary result: weekly change in bloating intensity did not differ from placebo, nor did days with and duration of bloating, abdominal discomfort or gas in the whole group. In the men only, bloating intensity and days, gas days and duration, days with abdominal discomfort and a diarrhea symptom score fell more than on placebo, by amounts the authors call clinical thresholds; the abstract gives no p-values for these and does not say whether the subgroup was planned. Physical functioning was better than placebo at week 2. Vital signs and blood tests stayed within normal ranges.
Single-center, phase 2, randomized, double-blind, placebo-controlled trial; 250 mg MB40 spores (10 billion CFU) or maltodextrin placebo once daily for 30 days; registered TCTR20210128003; funded by the National Research Council of Thailand and the US National Institutes of Health; the product was bought from BIO-CAT Microbials and no author was a maker employee (Piewngam et al. 2023, Lancet Microbe)
115 adults in the Songkhla region of Thailand who carried S. aureus in the gut, nose or both (55 probiotic, 60 placebo).
Primary outcome met: S. aureus counts fell 96.8 percent in stool and 65.4 percent in the nose on MB40 (P = 0.0001 and P = 0.0002 versus placebo), with no significant change on placebo. In people colonized at both sites, the stool difference versus placebo was not significant (P = 0.083). Overall gut microbiota did not change significantly, and adverse effects did not differ from placebo.
Single-blind, single-group study with a 1 week placebo lead-in, then one 250 mg capsule of 5 billion CFU MB40 twice daily for 21 days; retrospectively registered NCT04655352; paper also reports genome screening and a 14 day rat feeding study; funded by BIO-CAT Microbials, with two authors (Spears, Kramer) employed there and two consultants to the company (Spears et al. 2021, Nutrients)
30 healthy adults enrolled; 27 completed (12 men, 15 women, average age about 35).
No serious adverse events; five mild events, two (vomiting and chills in one person on the same day) judged likely related and resolving within 31 hours. Physical exams, lab results and vital signs showed no clinically significant changes, and weekly bowel movements were about the same as in the placebo week. There was no placebo group running alongside.
Randomized four-group piglet study: plain or MB40 diet for 14 days, with or without Listeria monocytogenes injection on day 8; funded by BIO-CAT, Inc., which took part in design, analysis and writing; three authors were BIO-CAT employees and one worked for BIO-CAT Microbials (Garvey et al. 2023, Microorganisms)
32 three-week-old piglets.
After the Listeria challenge, MB40 lowered bacterial counts in the liver by 67 percent and in the spleen by 49 percent compared with the plain diet (both p < 0.001), and was linked to fewer circulating monocytes. Animal results only.