Bacillus Subtilis for SIBO and Gut Health [Best Strains]

Science Based

Lactobacillus and Bifidobacterium are the two main groups of bacteria found in probiotic supplements.

But if you've had little success with them, or if they caused side effects, another option worth exploring is Bacillus.

Although Bacillus is a large group of bacteria, only a few species are used as probiotics, including Bacillus subtilis, Bacillus coagulans, and Bacillus clausii.

Today, I'm writing about Bacillus subtilis.

What Makes Spore-Based Probiotics Different?

The key difference between Lactobacillus, Bifidobacterium and Bacillus probiotics is that Bacillus can survive long-term storage, stomach acid and other harsh conditions.

From the study:

Overall, it has been found that the Bacillus strains with claimed probiotic properties showed greater viability than probiotic Bifidobacterium and Lactobacillus strains no matter the food studied. The percentage of survival of the Bacillus strains with claimed probiotic properties were always above 83%. The Bacillus strains with claimed probiotic properties were able to survive well in all the food matrices tested. Therefore, this study shows that these strains of Bacillus may comprise a feasible strategy for expanding the range of “probiotic food” choices given their high resistance to the composition of foods, manufacturing steps, and resistance to simulated GIT conditions.

Another thing often repeated in SIBO communities is that spore-based probiotics are much better than Lactobacillus for this condition, because they don't feed the overgrowth in the small intestine.

I haven't found any studies that directly support that claim, but several reputable gut experts I follow recommend soil-based probiotics, so I guess there must be some evidence or at least some clinical experience behind it.

Bacillus Subtilis Strains and Their Specific Health Benefits

These are the Bacillus subtilis strains you'll most often find in probiotic supplements.

Bacillus subtilis CU1

Bacillus subtilis CU1 for Immune Health

This study found that taking Bacillus subtilis CU1 during the colder months may support immune defenses and reduce the number of respiratory infections. This could be especially relevant for older adults, as the study participants were between 60 and 74 years old.

Bacillus subtilis CU1 and Inflammation

Another study also found that Bacillus subtilis CU1 can influence immune function and may help support the body's natural defences against infections.

What's more, it reduced low-grade inflammation associated with aging.

Can Bacillus subtilis CU1 Help with Diarrhea?

This time, Bacillus subtilis CU1 was used together with Saccharomyces boulardii CNCM-I 3799 to help manage diarrhea in children aged 6 months to 5 years.

Children who received the probiotics within the first 48 hours of diarrhea onset recovered roughly 14 hours faster than those who received placebo.

What's interesting is that children who had taken the probiotics had shorter and less severe episodes of diarrhea if they became ill again, suggesting that these 2 specific strains may have a longer-lasting protective effect on the gut.

Bacillus subtilis DE111

Bacillus subtilis DE111® and SIBO

This is one of the 3 different strains Dr William Davis recommends for his Super Gut SIBO yoghurt recipe.

The combination of L. reuteri DSM 17938, ATCC PTA 6475, L. gasseri BNR17 and B. subtilis DE111® (or B. subtilis HU58™) may help reduce bacterial overgrowth and rebalance the small intestine.

If you want to start with just one strain, you can use either B. subtilis DE111® or B. subtilis HU58™ and ferment it at home to achieve higher bacterial counts. Here's how.

Bacillus subtilis DE111® and Bowel Function

According to another study, this strain helped regulate bowel function by reducing the back-and-forth between constipation and diarrhea in healthy adults.

Bacillus subtilis DE111® and Other Health Benefits

Apart from the direct gut health benefits mentioned above, Bacillus subtilis DE111® may also improve cholesterol levels and support immune health.

Bacillus subtilis HU58™

Bacillus subtilis HU58™ and SIBO

This is another B. subtilis strain recommended by Dr William Davis as one of the most effective options for addressing bacterial overgrowth in the small intestine. If you're interested in making his Super Gut SIBO yoghurt or fermenting B. subtilis at home, I've added the links above (in the Bacillus subtilis DE111® section).

Bacillus subtilis HU58™ and Diarrhea

I found 2 studies supporting the potential of this strain to help with diarrhea: one in children with antibiotic-associated diarrhea and another in adults with IBS-D.

Here are the study summaries:

Spore-forming B. subtilis HU58 administered to children after onset of AAD may lead to faster resolution of diarrhoea and associated abdominal pain.

Supplementation with B. subtilis HU58 and H. faecalis SC208 for 4 weeks was safe and effective in improving stool consistency and abdominal pain in individuals with IBS-D, supporting its potential for symptom management in IBS-D.

Other Strains and Their Health Benefits

To write this article, I looked at studies, probiotic supplements and user comments. Besides the strains mentioned above, which seem to the most popular ones with research behind them, I also found these:

Bacillus subtilis BS50: this study suggests it may help relieve burping, gas, and bloating.

Bacillus subtilis AB22™: this is a relatively new strain, with several potential benefits mentioned on the manufacturer's website.

Bacillus subtilis MCTT 5981: I came across this strain in a probiotic supplement, but I haven't found much research on it.

The Bottom Line

Bacillus subtilis CU1, Bacillus subtilis DE111® and Bacillus subtilis HU58™ are the 3 strains with the strongest evidence behind them. If you're looking into Bacillus probiotics for SIBO, these are the ones worth considering.

Unfortunately, I've noticed that many probiotic supplements list only Bacillus subtilis without specifying the strain.

Also, I wish Bacillus subtilis HU58™ wasn't so expensive.