Soil-based organisms (SBO) or spore-forming probiotics are terms often used interchangeably, as most soil-based organisms do form spores. They get their names from their habitat: they tend to be found in the soil. Historically, our ancestors ate food right out of the ground, so many of these organisms would have been part of the normal flora.

Soil-based organisms nearly always come from the genus bacillus, unlike the more traditional probiotics which come from lactobacillus or bifidobacillus.

Are Soil-Based Probiotics Beneficial?

Even though lactobacillus and bifidobacillus are far and away the most numerous (and therefore the most well-studied) probiotic organisms in the gut, there are plenty of studies that show health benefits from supplementing with bacillus species, as well. Here’s just a few:

Bacillus coagulans has been shown to improve abdominal pain and diarrhea in patients with Irritable Bowel Syndrome.
Bacillus coagulans is beneficial for constipation.
Bacillus subtilis can help keep H. pylori in check.
Bacillus species in general support innate immunity.

All of these things can be said for traditional probiotics as well, of course. Perhaps the biggest claim to fame for soil-based probiotics is that they are better able to survive stomach acid and digestive enzymes intact, until they arrive in the intestines where they are able to colonize. They also tend to be more antibiotic resistant.

So the question is, how big a deal is this? Do traditional probiotics survive the harsh digestive environment well enough to make a difference?

Survivability of Traditional Probiotics

One of the important jobs of stomach acid is to neutralize ingested pathogens—indeed, those with low stomach acid are more susceptible to foreign invaders. Few pathogenic organisms can survive pH below 3. But fortunately, a few can—specifically those in the bifidobacillus and lactobacillus genera. This has been shown repeatedly in healthy volunteers, suggestive that the concern that regular probiotics will not reach their intended target is unfounded.

All organisms have been shown to be sensitive to bile salts, though—one reason why there is a significant association between SIBO and gallbladder dysfunction. I suspect this means that if you do take your probiotics with food, it’s a good idea not to do so with a fatty meal.

Given these findings, additional precautions for traditional probiotics such as enteric coatings to help the organisms withstand stomach acid are probably not necessary. Also, the compounds used in enteric coatings may not be healthy.

Enteric Coatings: Are They Helpful or Harmful?

Some of the most common polymers used for enteric coatings are these:

Phthalates. These plastic derivatives are associated with endocrine disruption. Phthalate polymers used for enteric coating include cellulose acetate phthalate (CAP), hydroxyl propyl methyl cellulose phthalate (HPMCP), and polyvinyl acetate phthalate (PVAP).
Cellulose acetate trimellitate (CAT). These are chemically quite similar to CAP (listed above).
Hydroxyl propyl methyl cellulose acetate succinate (HPMCAS). This is a rigid polymer which is further plasticized to render it easier to work with.
Methacrylic acid copolymers.

The general rule of thumb I offer my patients when reading labels for food, cleaning, or personal care products is this: if you don’t recognize the name of it, don’t eat it, inhale it, or put it on your body. Any foreign compound will require your liver to detoxify it—and your liver is overworked enough already in this toxic world we live in. Best to avoid anything mysterious and multiple syllables long.

The Upshot

Soil-based organisms seem to be beneficial, though no more so than traditional probiotics involving lactobacillus and bifidobacillus, so far as I can tell.

And I wouldn’t bother with enteric coating for your probiotics, as they’re likely to do more harm than good.

Are Soil-Based Probiotics Better than Traditional Probiotics?