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'Hold Off on Soil Based Probiotics,' says Gut Health MD


Our team at BINTO sat down with Will Bulsiewicz, MD, (Dr. B, the Gut Health MD) to discuss the safety and efficacy of soil based probiotics.


BINTO: How are soil based probiotics different from regular probiotics?

Dr. B: The concept of a probiotic has a strict definition. It is a living organism- not necessarily bacteria, it could be a yeast- that has demonstrated the ability to provide health benefits for another living organism. Many times, people use this term liberally. In order to be a probiotic, it has to demonstrate in study, benefits to people’s health.

The idea of taking bacteria and consuming them for the purpose of a health benefit is not new, it has been around for over 100 years. It’s just that in the last 10-15 years it has become a mainstream, massive industry. With that, has come some new ideas on what could potentially be a good probiotic. One of those ideas has been soil based organisms. Go back 200 years ago, there was no chlorine in our water, nor the excessive amounts of cleanliness that we see today. People were eating fruits and vegetables that were probably covered in dirt, and to some degree there was consumption of this dirt. A theory started to circulate that, perhaps, that’s what we’re missing today, and that might be part of the reason why we’re seeing a rise in digestive conditions, autoimmune disease, and cancer. These are the 21st century epidemics tied back to gut health.

There are multiple companies that have come to market with microorganism based supplements that are designed to fulfill this theory. These microorganisms are categorically different than the ones we traditionally used in our probiotics. They’re a totally different type of bacteria, coming from a different type of family. They’re not like Lactobacillus or bifidobacterium. Those probiotics have demonstrated, in numerous health studies, to have benefits for certain conditions. I don’t think there’s any debate regarding their effectiveness in said studies. Now, enter the soil based organism called Bacillus (a group of microorganisms come from the Bacillus genus, but there are many different species that fall under that umbrella). There has been a development of supplements with these microorganisms because they are considered “soil based” microorganisms- fulfilling the public desire based on the theory that we’re missing out on microorganisms found in dirt.


BINTO: Okay- so what’s the word on these soil based microorganism supplements?

Dr. B: The problem is that the degree of consumption and the hype is way out in front of the actual science and research to support their use. There are some studies- numerous in animals- that have demonstrated benefits. We can’t translate that, though. It’s not appropriate to use animal studies to define how we should treat humans for disease. As for human studies, the vast majority contain a dozen or so people using this soil based microorganism supplement. It’s extremely limited data, so I feel its too early to say there are clear cut benefits.

The flip side is these supplements may actually be damaging. The idea of taking a capsule that contains extremely high quantities of these microorganisms is conceptually totally different than having dirt on plants you’ve eaten. We don’t know what effect this will have, it may be very harmful.


BINTO: Are there any concerns about Bacillus?

Dr. B: Part of the reason why there’s question about the Bacillus family, is that there are several species of Bacillus bacteria that are exceedingly dangerous. For example, anthrax is produced by this group of bacteria. That is a specific species of bacteria (B. anthracis) that you would never find in supplements, but there are other types of Bacillus that are known to cause disease. So, that’s part of the reason why the medical community wants to pump the breaks before we have more information.

Additionally, these microorganisms are generally not considered to be part of the human microbiome. There is limited data that they may take up residence, but if you look at the general human microbiome, this is not a significant part of what constitutes it. One of the concerns is if you take a high concentration of something that is not native to the human microbiome, without adequate study, how do you know what effect it’s going to have? It could go in there and actually wreak havoc on your body.


BINTO: So, if these soil based “probiotics” are potentially harmful, why are they so popular?

Dr. B: Part of the hype with these microorganisms is that they’re more hardy than traditional probiotics (i.e Lactobacillus). They are designed in a way where they can survive stomach acid and bile, which can be damaging to other microorganisms. Because of that, there’s much higher delivery to the further parts of the intestine and the colon which is where you’re trying to deliver your probiotic.

From the manufacturing side of things, this is a way easier route. It’s so hardy, it holds up to a higher temperature. The problem is, we don’t have studies yet to support they accomplish what people claim they do. People use this designation of a probiotic as a supplement to innovate and try new things like this, but without consumer protection that is required by a pharmaceutical. They’re being developed in a lab and immediately brought to market without anyone checking if they’re safe. These companies generate hype through powerful marketing techniques so people believe these narratives to be true, but the science is not there yet to support it.


BINTO: How do you know what probiotic is safe and effective?

Dr. B: When selecting a probiotic, you should have a specific goal in mind of what you’re trying to accomplish. Then, use available research to help you identify what are the probiotics that are actually beneficial for that goal. Until the soil based microorganism supplements come forward with stronger data that truly support their use for specific conditions, I personally would not recommend them for my patients.

To give the Cliff Notes version of what to look for in a probiotic: if you have a specific condition like IBS diarrhea or IBS constipation, you should look to research posted online to identify what probiotic at what strength has been demonstrated, in study, to be effective for that condition.


Generally speaking, our studies suggest that:

  • The higher the number of CFUs, the better
  • You want to look for a  diversity of beneficial strains
  • It should have a delayed release capsule that protects the microorganisms and delivers them to the further parts of the small bowel and colon.

Note: There is value to things that are more hardy or temperature sensitive, but you never hurt yourself by putting your probiotics in the fridge. It only can lead to better preservation of the probiotic.

People don’t want to hear what their grandma told them as a kid, but at the end of the day, what you eat, the amount of sleep you get, drinking water, exercising… the simple lifestyle choices come back to provide health benefits. These are the the things that really drive a healthy gut. Probiotics can supplement that, but you’re not going to redefine the makeup of your gut with a probiotic by itself.


 Will Bulsiewicz, MD MSCI (“Dr. B”) is a graduate of Georgetown University School of Medicine. He trained in internal medicine at Northwestern Memorial Hospital and gastroenterology at The University of North Carolina Hospitals. He also earned a Master of Science in Clinical Investigation (MSCI) from Northwestern University and a certificate in nutrition from Cornell University. Dr. Bulsiewicz is board-certified in both internal medicine and gastroenterology.


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