Probiotics containing the antioxidant-producing B. subtilis have produced promising results in studies of constipation and H. pylori infections. They may also help support the immune system, liver function, and dental health. What is the latest science on this previously popular probiotic? Find out here.
Bacillus subtilis is a spore creating Gram-positive bacterium, found in soil and the gastrointestinal tract of ruminants, such as cattle, goats, and sheep. It is also found in the human GI tract.
This bacterium is widely used on an industrial scale by biotechnology companies, for the production of enzymes, pharmaceutical components, and GMOs. As a human probiotic, however, Bacillus subtilis has been somewhat neglected.
Bacillus subtilis cultures were popular worldwide before the introduction of antibiotics when Bacillus subtilis was used as an immunostimulatory agent to aid the treatment of gastrointestinal and urinary tract diseases. After the 1950s, with the introduction of antibiotics, this probiotic declined in popularity.
On the other hand, Bacillus subtilis has been extensively used in the livestock and poultry industries as antibiotic alternatives .
Bacillus subtilis is used in the commercial production of the Japanese food natto, as well as the similar Korean food cheonggukjang. Furthermore, a formulation containing a combination of Enterococcus faecium and Bacillus subtilis has been available and widely used in Asia since 1994 .
B. subtilis has demonstrated DNA protective and antioxidant (superoxide scavenging) activity in a laboratory setting .
B. subtilis probiotic supplements have not been approved by the FDA for medical use. Supplements generally lack solid clinical research. Regulations set manufacturing standards for them but don’t guarantee that they’re safe or effective. Speak with your doctor before supplementing.
In one of the Asian clinical trials, a mixture of E. faecium and B. subtilis improved abdominal pain, distention, and fever in patients with acute diarrhea. However, most of the trials did not find a significant difference with these probiotics in acute diarrhea treatment .
Results were more encouraging in chronic diarrhea patients, where a significant increase in Bifidobacteria levels following therapy was observed. Treatments also prevented diarrhea relapse .
B. subtilis together with E. faecium significantly reduced the severity and frequency of abdominal pain in patients with Irritable Bowel Syndrome (IBS) in a single Asian clinical trial, however other results are not as convincing, and further studies are needed .
In Asian studies involving patients with ulcerative colitis, the addition of a B. subtilis probiotic significantly reduced the number of days with bloody stool, led to complete remission without relapse, and significantly increased the efficacy of mesalazine or sulfasalazine therapy .
A higher dose of B. subtilis administration ameliorated dysbiosis and gut inflammation by balancing beneficial and harmful bacteria and associated anti- and pro-inflammatory cytokines in mice .
B. subtilis reduces inflammation and suppresses colitis in rats .
In a study of 352 patients, B. subtilis containing probiotics improved H. pylori eradication and decreased diarrhea and total side effects when used in conjunction with triple therapy .
Researchers are currently investigating whether B. subtilis has other health benefits. The potential benefits in this section have produced positive results in at least one clinical trial, but these studies are small, contradictory, or otherwise limited. Talk to your doctor before supplementing with B. subtilis for any reason.
B. subtilis inhibited disease transmission in patients with acute non-typhoid Salmonella gastroenteritis .
Metabolites of B. subtilis decrease the resistance of urogenital pathogenic microflora to antibiotics in patients with urinary tract infections, resulting in accelerated elimination .
Spores of B. subtilis attenuate the symptoms of Clostridium difficile infection in mice .
B. subtilis suppresses infection and enteropathy in suckling mice infected with C. rodentium .
According to a review, a probiotic containing both B. faecium and B. subtilis shifted the intestinal microbiota of 70 patients with liver cirrhosis back towards levels observed in healthy subjects. These probiotics also reduce circulating endotoxin levels in cirrhotic patients with endotoxemia .
Bacillus subtilis reduced periodontal pathogens in humans .
Bacillus subtilis and Bacillus licheniformis supplementation provided a protective effect against bone loss in rats with periodontitis .
No clinical evidence supports the use of B. subtilis for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies listed below should not be interpreted as supportive of any health benefit.
Diabetic patients who develop foot ulcers are at more risk of dying prematurely than those without the complication. B. subtilis shows antimicrobial activity against four diabetic foot ulcer bacterial pathogens. However, this activity has not been tested in clinical trials of human patients with foot ulcers .
B. subtilis spores stimulate the immune response when co-administered with a vaccine for papillomavirus type 16 (HPV-16) in mice .
Continuous oral administration of B. subtilis alleviates the development of skin lesions in mice with atopic dermatitis .
Exposure to extreme heat can cause illnesses and injuries. Bacillus. subtilis was effective in the prevention of complications related to heat stress in rats. When rats were subjected to heat stress (45 °C), adverse effects such as morphological changes in the intestine, bacterial translocation, elevated levels of LPS and IL-10, and increased vesiculation of erythrocytes were observed only in animals not protected with B. subtilis .
Components of Bacillus subtilis inhibit colon cancer cell growth [30, 31], hepatocellular cancer cell growth , cervix carcinoma cell growth , and the growth of human leukemia cells  in laboratory experiments. These results do not reflect whether B. subtilis might be helpful in cancer prevention or therapy; they simply indicate that further research is warranted.
Various studies have investigated B. subtilis’s effect on the cellular level. These may or may not reflect the mechanisms of B. subtilis probiotics in the human body; however, they may help account for some of the observed effects of these probiotics in human studies.
- Increases IL-8, IL-12  and TGF-β 
- Mostly increases IL-10 [12, 11, 13] (a study where IL-10 is decreased: 
- Increases IgA [15, 26] and IgG 
- Decreases IL-4 , CXCL-1 
- Both decreases [11, 13] and increases IL-6 
- Both decreases  and increases TNF-α 
- Both decreases  and increases IL-1β 
- Both decreases  and increases IFN-γ 
- Increases ACP, LDH, NO, and iNOS 
- Decreases glutathione reductase (GR), xanthine oxidase (XO), heat-shock protein 90 (Hsp90), and lipid synthesis gene 3β-hydroxysteroid-∆24 reductase (DHCR24) 
Bacillus subtilis is safe and well tolerated by healthy adults [36, 37]. However, its use in rare cases can lead to bacteremia (infection) , hepatotoxicity  and heavy exposure to spores can cause allergic asthma .
To avoid adverse effects, talk to your doctor to determine whether probiotics are safe and appropriate for you.