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Probiotics: More than expensive poop?

Probiotics are one of the most intriguing natural medicine therapeutics. A probiotic is a live microorganism (usually bacteria) that is taken orally, topically, or rectally in an effort to influence and shift biochemical, microbial, and physiologic state of some system in the body. Since humans are born with a relatively sterile digestive tract and in the first few days it rapidly accumulates flora from mom via breast milk, skin contact, and the environment; we innately understand the pivotal role that gut microbes have on our digestion, nutrient absorption, and survival. And since much of the microbiome research from the American Gut Project pointed that gut microbiota diversity is a key in health and longevity; we have seen a growing interest in figuring out the best way to shift the microbiome. The use of probiotics is rampant with the sales of probiotics globally projected to reach 65.87 billion by the year 2024. We can assume that a fair percentage of people taking probiotics are experiencing noticeable benefit and some may not be benefiting at all from taking probiotics. The illusion that we can take a probiotic and make it grow in our gut has since been dismantled and now we are trying to conceptualize why and how probiotics work and which specific strains are most beneficial for certain diseases. In my practice, I use probiotics for all types of digestive disorders, skin disorders, allergy disorders, and mental health concerns. However, they are chosen artfully and used at specific times and status of a patient’s health status. I have posted on various issues with probiotics as well including the fact that some times probiotics may make people feel worse. I also have growing interest in therapeutic prebiotic use. See, prebiotics are non-digestible fiber components that support our microbiome. Also, an interest in the direction of fecal microbial transplant for more long-term microbiome shifts. Recently I invited an esteemed colleague Dr. Jason Hawrelak (The probiotic advisor) on my podcast.

Below I am sharing a summary of that conversation. To listen to full episode click here. The full transcript of this podcast is at the end of the post.

Jason Hawrelak, PhD, ND , the probiotic advisor on Probiotics

About our guest:

Jason Hawrelak, PhD, is a research scientist, educator, naturopath and Western herbalist with nearly 20 years’ clinical experience. Jason practices at Goulds Natural Medicine, a 138-year-old natural medicine apothecary and clinic located in central Hobart in Tasmania, Austrailia. Dr Hawrelak did his Honours and PhD degrees in the areas of the gastrointestinal microbiota, the causes of dysbiosis, and the clinical applications of pre- and probiotics. He has written extensively in the medical literature on these topics – including 16 textbook chapters – and his research has been cited nearly 1000 times.

Dr Hawrelak has taught health professionals at both the undergraduate and postgraduate level for the past 18 years. He currently coordinates and teaches the Evidence-based Complementary Medicine Programs in the College of Health & Medicine at the University of Tasmania (Hobart, Australia) and teaches natural approaches to Gastroenterology within the University of Western States Master of Science in Human Nutrition and Functional Medicine program (Portland, Oregon). He is also a Visiting Research Fellow at the Australian Research Centre for Complementary and Integrative Medicine (ARCCIM) at the University of Technology Sydney (Sydney, Australia).

Jason is on the Medical Nutrition Council of the American Society for Nutrition and is a Fellow of both the American College of Nutrition and the Naturopaths and Herbalists Association of Australia. He is also Chief Research Officer at, which offers a searchable database that enables easy, evidence-based prescribing of probiotic products and online resources for clinicians, and health-conscious members of the public, to learn more about the human microbiome and how they can positively influence these ecosystems.

Background and interest in probiotics:

Dr. Hawrelak’s interest in probiotic began in his final year of Naturopathic training and he attended 1999 lecture on microbiome and it drew his interest. He was at a research institution and did a research project on a prebiotic, probiotic, herbal combination. He went on to do a PhD with emphasis on this topic and in 2000 did his honor thesis on probiotics. 20 years later is still passionate about his PhD topic.

Definitions of Probiotics:

The strict definition and criteria determining if something qualifies as a probiotic of probiotics is as follows;

○ It must consist of live microbes, when administered in adequate amounts, that have demonstrated therapeutic effects in humans. Human clinical studies done with the exact human strain used in the product.

○ It must have gastric acid stability (be able to survive the stomach pH)

The different types of probiotics include

  • Food sources of probiotics: typically a yogurt base with a probiotic integrated into the probiotic including Medicinal yogurts and Medicinal Kefir

  • Human origin strains (a lot of the lactobacillus and bifidobacterium strains found in probiotics are human origin)

  • Yeast based probiotics : Saccharomyces boulardii (from the skin of Lychee) also Saccharomyces cerevisiae.

  • Spore based probiotics : Bacillus clausii ( fromphylum firmicutues) .Bacillus clausii, has been found to produce antimicrobial substances that are active against gram positive bacteria including Staphylococcus aureus, Enterococcus faecium, and Clostridium difficile. Bacillus Coagulans which is originally from cow intestinal tracts. Also see Bacillus subtilis, an endospore, gram positive, bacteria found in soil and the gastrointestinal tract of ruminants and humans. Can survive in anaerobic environments. Bacilus subtilis is strongly antimicrobial.


Dr. Hawrelak states this is a class of agents poorly used by clinicians

● He points out that they do more then feed bacteria

● The definition of a prebiotic is as follows :

○ A substrate that is selectively used by host microbes conferring a health benefit.

○ Must be indigestible

○ They must be a selective substrate for 1 or more commensal bacteria primarily in the large intestine.

○ They shift the ecosystem to a healthier state

○ There is some benefit from the ecosystem shift

● Many fibers do not meet the definition of prebiotics

Most prebiotics will increase bifidobacteria, akkermansia, lactobacilli, faecalibacterium, and butyrate producing bacteria. (hence the importance of prebiotics in the diet)

See my handout on prebiotics here.

Myths and controversy of probiotics

● There is a long standing and hopefully squashed myth that probiotics permanently colonize the GI tract. 95% of the time there is no long-term colonization. Probiotics may stick around for 2 weeks at most and usually cannot be seen on stool testing after you discontinue taking.

● Yet, probiotics are still therapeutic even though probiotics are not inoculating the intestine

● The probiotics have an action while you are taking and you will benefit for that time and a number of days afterwards

● Some probiotics for example decrease cholesterol; they will only benefit you while you are taking the probiotic. Once you stop the benefit stops.

● For hyperlipidemia (high cholesterol) the following strains of lactobacillus probiotics (L. plantarum and L. reuteri) have been beneficial in reducing cholesterol

● The other often debated question.When should you take probiotics when on antibiotics? According to Dr. Hawrelak, take them spaced between antibiotic dosage. Don’t wait until after the course is done!

Researched indication for probiotics

● Traditional uses: Irritable bowel syndrome, Inflammatory Bowel Disease, and Antibiotic related gut issues

● Emerging indications: Alzheimer's disease, anxiety, asthma, rheumatoid arthritis, mastitis, chronic fatigue syndrome, cervical dysplasia, celiac disease.

● Endometriosis is being studied with a non-commercially available strain

● We will eventually have a probiotic materia medica to co-exist with herbal materia medica.

● Esschericia Coli Nissle 1917 has good evidence for IBD. Been available since 1920’s. N. America is cautionary because of E. Coli association.(ask me about patients of mine flying through Germany to stalk up on this one!)

● Strains are not available worldwide. This is slowly changing. Europe is leading the way in probiotics.

Shopping for probiotics, how to select a good strain?

● If generally healthy, Dr. Hawrelak says you are better off getting your probiotics from fermented foods such as sauerkraut, kimchi, and yogurt vs. taking probiotics.

● Even though yogurt bacteria will die in the small bowel; there can be some benefit to immunity/natural killer activation related to even dead probiotics.

● For specific use of probiotics, you need to work with a health practitioner.

● Don’t use label claims to make your decisions.

● High CFU and most species/multiple strain does not equal a good selection of a probiotic. For example: Antibiotic associated diarrhea. 60 billion CFU multi strain (4 strains) Vs. 1 strain Lactobacillus reuteri ATCC 55730 200 million strain, single strain . The 200 million did help reduce diarrhea rates and c.difficile rates but the larger multi-strain probiotic did not. See study here on Lactobacillus reuteri

Evaluating microbiome for probiotic selection

● Dr. Harwelak uses lactulose/mannitol for checking intestinal permeability. Arguably the most validated test for gut leakiness. Tells you how severe. (authors note: there are others including stool or serum Zonulin and also panels looking at Actomyosin IgA, Occludin/Zonulin IgG, Occludin/Zonulin IgA, Occludin/Zonulin IgM ,Lipopolysaccharides (LPS) IgGm Lipopolysaccharides (LPS) IgAm and Lipopolysaccharides (LPS) IgM)

● Healing intestinal permeability can be a 3-12-month process.

● Example Chronic Fatigue Syndrome patient. Had intestinal permeability. Was 80% improved after 12 months of gut healing protocol. This was consistent with his improvement in the lactulose/mannitol testing.

He also uses microbiome testing. American Gut Project, Thyrve[1], 16srRNA testing. Is a game changer. He has found that the overall diversity score and number of species on these tests is very helpful. Only $100 follow up testing. Gauges changes and dietary compliance. Example Bilophila wadsworthia (a gram-negative, obligatorily anaerobic, bile resistant bacteria) will be high if someone is on a high fat diet. It only feeds off bile. Bliophila wadsworthia produces hydrogen sulfide gas which is something we want to be careful with it. (authors note Hydrogen Sulfide production has been linked with intestinal inflammation ) Follow up testing helps with motivation and understanding how well treatment recommendations are working. These are now essential tools that have improved the results.

Dangers, contraindications, and warnings in probiotics

● Systematic studies say to be careful with yeast-based probiotics specifically like saccharomyces boulardii in hospitalized immuno-suppressed patients.

Future work and take-home messages from Dr. Hawrelak

● Looking at research for natural agents that will not harm our commensals. He is concerned that some of the herbal medicines we use for sibo and dysbiosis that are being used for long term use may actually harm the microbiome.

● He is continuing to build the Probiotic advisor data base.

● He states to choose probiotic tools wisely. Based on evidence. Not on manufacturer information.

● Prebiotics are undervalued and are the best at shifting microbiome

○ Used for obesity and metabolic issue as well

○ Prebiotics and prebiotic supplements taste good!


One of my favorite articles on prebiotics by Lauren Glucina, a New Zealand based Naturopath, Medical Herbalist and Nutritionist

Addition comments on the topic...

Plethora of possible mechanisms of Probiotics.

Probiotics have taken a big hit in scientific and lay person circles. Mainly because people think that we are just making expensive “poop” and that since probiotics do not necessarily permanently grow in the gut then they are a waste. Well many research models have continued to show some of the beneficial shifts that might happen while on probiotics. I think the graph below really highlights a few. Probiotics are best viewed like a medicine and once you stop then the benefits will likely taper down. Prebiotics might be looked however more of a longer-term move. For now these are some of the benefits of probiotics proposed.

(Hill et al., 2014)

Courtesy of Hill, et. al. 2014

When I think of this list as a clinician, I would rank the following as most noticeably:

  • Regulation of intestinal transit (better stool consistency and frequency)

  • Neurological effects (I will often see less anxiety and depression)

  • Reduced intestinal permeability ( probiotics help in some cases improve mucus lining, and helps reduce endotoxin levels)

  • I typically see less gas and bloating

However, do note, in my practice we focus on really specific strains and not mega volume, multi-species probiotics. Also, probiotics are usually introduced at a later stage of health stability in my patients. Hence, the body is usually in a better state to integrate this microbiome shift.

Future directions of probiotics will likely be further exploration of the long-term benefits of spore-based probiotics. I am personally interested in the spore-based probiotic Bacillus subtilis (HU-58) as its ability to live in anaerobic environment and release antimicrobial elements that may be effective in warding of pathobionts make it an attractive option. Also developing a flexible and prebiotic-centric diet

If you are generally well and want increase prebiotics in your diet you may start with something like a prebiotic smoothie bowl. Warning : if you currently on unstable digestively adding prebiotics rapidly like this may lead to more GI-distress temporarily. For the recipe ; Check it out below

Recipe courtesy of

Transcript of episdode

Dr. Adam Rinde: What's going on everybody? This is Dr. Adam Rinde and welcome to the next episode of The One Thing Podcast. Today, we're speaking with a probiotic expert, Dr. Jason Hawrelak, all the way from Tasmania, Australia.

He will take us through all the fundamentals of probiotics and we will speak deeply about clinical applications of probiotics, how to know which ones are proper to select, some of the controversies around probiotics and we will walk away with a better understanding of how to utilize probiotics for health and for specific health conditions. Without further ado, welcome our guest, Dr. Jason Hawrelak.

I'm here today with Dr. Jason Hawrelak. Jason, welcome to The One Thing Podcast. It's great to have you here. I thought we could just jump right into the interview and hear a little bit about what brought you into the microbiome space and interest in probiotics.

Dr. Jason Hawrelak: Thanks, Adam. It's a pleasure to be here and chatting about my favorite topics that you couldn't even give me this shut up about even once. What started me was almost like one of those random chance events that I was in my final year of my naturopathic training and there was this just fantastic lecture by one of our senior academics on what the data was around dysbiosis and increased intestinal permeability in these different disease states and this was back in 1999.

Probably 20 years ago now actually is probably at the time of his lecture and it really triggered something me passion drive to learn more and I was lucky that that it was at a research institution and I've trained here in Australia.

Where we have the opportunity to research honors degree which is essentially, we do a research project and we actually end up in the end doing a human clinical trial of a prebiotic-probiotic herbal combination for the treatment of IBS which my literature review started back in 1999 and followed that up with it with a PhD looking at the same topic area.

So, amazingly well timed because you had no idea about the boom that was supposed to happen but this was that area that was immense interest to me and it's always been an area of intense interest for naturopath broadly speaking, but there's some that it just really resonates well with and for me, it wasn't a health issue per se because I would argue that my health issues are mostly lung related but it just something that really captivated me and I just had to learn and delve more.

I'm really lucky that I chose a topic that 20 years on, I still find immensely interesting and I'll still read papers late at night and watch other people lecturing late at night. There's a lot of people do their PhD in a topic that they really found boring and they just did it to get a PhD. Whereas I'm lucky that I chose a topic that I'm passionate about.

Dr. Adam Rinde: It's in the prime time right now. You can't open your browser without seeing a study every day about microbiome, probiotics and you're there at the right time.

Dr. Jason Hawrelak: It's pretty amazing to be from that time point and when I was writing my honors thesis in 2000 like going back and looking at all the probiotic research and all the microbiome research and you can read all of it back from the stuff that was done in the '70s, '80s and '90s.

So there wasn't that much and there's only a few research centers and researchers around the world who really focused on it and who were passionate about it and they were managed to pass on that passion to me, as well.

So, that absolute love and this idea of protecting and being custodian of the microbiota really grew out of that early research that was around that time point and certainly expanded dramatically due to changes in technology, which has allowed us to see so much more.

Now there's 1000s of researchers around the world, many 1000s are working on this area so the level of evidence is just powering more and more space all the time as you said before.

Dr. Adam Rinde: people are familiar with probiotics by now. People can just go to the supermarket, grab some yogurt, and they'll see that there have been customized to have certain probiotic strains in them. There's Kombucha on the shelves. So, it's not this conversation is likely to fall in the ears of someone who hasn't heard of probiotics.

This is likely to be listened to by clinicians but also health consumers and people who are dealing with health challenges, but I thought we could start out with just discussing the different types of probiotics and different categories because it can get quite confusing for people to understand everything from symbiotics to spore based products. If you could walk us through just some descriptions of these different categories.

Dr. Jason Hawrelak: I'll just take a step back to and just look at the definition of probiotics. We've all got a general idea but it's worth teasing out of the most commonly accepted definition at this time point, which is live microbes that when administered in adequate amounts confer a health benefit on the host.

If you take that definition apart, there are three components live microbes number one. Even if you have a therapeutic product that has lovely clinical trials on it, showing it works but it contains dead bacteria, it's actually no longer a probiotic at that time point.

Secondly is the adequate amount and once again, you can often look at some the range of probiotic products on the marketplace and see that many might well contain live microbes and they might contain those that has therapeutic effects shown in human studies, but don't have adequate amounts to actually have a therapeutic effect when we're given in that form that is recommended dosage.

So, that again would not be a probiotic and the third part of that definition is some parts of the world take that component where it confers a health benefit on the host very strictly, where you need human clinical trials done on the exact genetically unique strains found in your product for you to use the term probiotic you describe in your product.

Because if it doesn't have you in clinical trials, you can call it a source of microbes but you can't actually call it a probiotic itself. So, it's worth teasing out those aspects. If you look at how few products out there that claim to be probiotics actually meet that strict definition and a lot of those would be in a category of food and even within that food category.

You'd have what probiotic researchers would call sources of live and active culture which would be typical Kombucha's, Kefir's, Sauerkraut, Kimchi, where you're getting live microbes in generally large amounts.

They're wild ferments, so you really don't know about the potential of the strains that you're consuming. You don't know about the basic details of those strains. Do they have the characteristics that are essentially vital to have a chance of producing therapeutic effects in humans and that would be things like gastric acids stability, bile salts stability.

So that it can survive transit to the upper gut, can adhere to intestinal cells, does it produce the antimicrobial compounds that might have a selective decontaminating effect on the ecosystem or shift the ecosystem into something better.

And then, there's another category of those food sources of microbes that would meet the definition of probiotics where you might have a yogurt base, which would use a nondescript strain of Lactobacillus delbrueckii subspecies bulgaricus and Streptococcus thermophilus.

Those are the two species that always made milk into what we call yogurt today but they limit in their capacity to have any greater therapeutic effect, because in general they don't have the capacity to deal with gastric acid or bile. So, they will generally die in the stomach and small intestine.

This has been known for a long time. So, what some companies will do will actually add well characterized, well researched probiotic strains into that yogurt or kefir or kimchi potentially too.

You're getting fermenting bugs that are in that wild varying amounts of microbes, a whole range of different species and strains might be there but then you're also getting these therapeutic strains on top of that and that would define them as more medicinal yogurts or medicinal kefir.

So, I'd actually separate them quite clearly based on the addition of those human well researched therapeutic strains versus just the wild ferments rather than was there.

Dr. Adam Rinde: So, once my probiotic has met those particular qualifications and they do fit the probiotic definition, then take us from there. Let's say that they do have live microbes in adequate amounts and have been used in clinical trials. There still is separate categories, correct?

Dr. Jason Hawrelak: There might be ones that are based on lactobacill,i bifidobacteria based. There's a few exceptions to this but it essentially initially isolated from healthy human people. We don't like to think of it that way. My patients like to think of the fact that they're ingesting microbes that were originally isolated from someone else's poo but that's the reality.

So, some people have described it as more human origin strains and the idea has always been that because they came from human guts that they probably like living in a human intestinal tract environment in terms of the pH will be to his liking, the temperature will be to his liking, the food that we eat will be to its liking.

But there are other probiotics that have other origins. They're saccharomyces cerevisiae variety boulardii was isolated from the skin of lychees back in the 1920s. Henri Boulard was a microbiologist, went to Southeast Asia.

There's from memory a cholera epidemic going through and he noticed that that some locals were drinking this tea made from lychee skins and they were one not getting cholera into getting better. Coming from a microbiology background, he obviously assumed there was some microbe on it. So, he isolated a yeast which he then named after himself.

That microbiologists do and that's been used as a probiotic sold around the world since 1950s which is quite fast in terms of the duration of time that's been sold as a probiotic supplement isolated from skin of lychee and there's no other probiotics come from lychee's skin that I'm aware of.

There's a newer class that people have brought into the market in the last 10 or 15 years which is so called soil based probiotics that originally had their origin from microbes standing in dirt.

Dr. Adam Rinde: That's the spore-based probiotics.

Dr. Jason Hawrelak: Many would fit into that category. Taking another step back, there's some like bacillus clausii. It's a spore-based probiotic that has been sold as a probiotic in Italy for decades that does have long history of use. There's another bacillus coagulans that I read about. I can't remember the strain designation but originally came from cow intestinal tract.

So, there are some that have other origins as well and research is certainly clear that it doesn't have to be from humans. It just has to be therapeutic. That's clear thing. If it wasn't a clinical trial showing it works and it came from a cow or came from soil, or it came from somewhere else, then there's no way of knowing it works essentially.

Dr. Adam Rinde: Let's go through prebiotics versus probiotics. Besides the obvious if you could just take us through some of the key elements of what a prebiotic is and comparison to probiotics.

Dr. Jason Hawrelak: Prebiotics are a class of agents that are poorly utilized by clinicians. That's been to change I can see but that's certainly been the case. It's partly due to a lack of clarity around what the definition actually is because people often just assume prebiotics feed bacteria and that's it. It's not quite right because again the strict definition is a substrate that is selectively utilized by host microbes conferring a health benefit.

For a food ingredient or something, et cetera to be classified as prebiotic, they have to meet four criteria, one be indigestible so we can't break them down or absorb them because then they won't reach the lower gut to be therapeutic.

Two, they act as a selective substrate for one or a limited number of what we generally see as beneficial commensal bacteria in the large intestine primarily. Three, they shift the ecosystem to a healthier state and four, there's some health benefit that comes from that shift. When you strictly enforce that definition, there's a lot of things that don't meet that.

There's a whole range of dietary fibers, which are essential for us to be consuming but they don't meet that definition of prebiotic because they might feed 30, 40, 50 different species in the gut and that's not a bad thing.

It's just that they're not prebiotics by definition, whereas the prebiotic really is selective. If you do really good stool testing, you can clearly see this on the before and after results of supplementing with a prebiotic supplement is you'll see exactly what the research tells you. You'll see an increase of most prebiotic supplements that we have access to now will target Bifidobacteria.

There are some there will also feed a bit of Lactobacilli. Some that will feed up the Faecalibacterium and Akkermansia. Those would be probably the four with the best data set and another group called butyrate-producing bacteria, which is a broader group of organisms.

But you can clearly see the shifts and this is where prebiotics are absolutely wonderful. When you have an ecosystem, you assess the ecosystem and say, "The diversity is okay but you're actually really low in Bifidobacteria or potentially below detectable levels of Bifidobacteria. Here, we can introduce a prebiotic into their regime.

You can do a follow-up test in two months and you'll see almost exclusively the Bifidobacteria population goes up. It's pretty clear how selective it is but you also get because of the shift in environment that occurs with that prebiotic ingestion generally a lowering of the pH because you're getting increased short-chain fatty acid production due to feeding Bifidobacteria generally or Faecalibacterium or Akkermansia.

You will get a reduction in potential pathogens as well pathobiont populations. Pathobiology is a term often used in the microbiome literature that's really describing species that when present in the right amounts and the right area are actually helpful and don't cause any harm.

But if they have a chance in the wrong environmental conditions or the wrong numbers causes harm and then most of the research around dysbiosis is around that definition pathobionts rather than single isolated pathogens.

But what I love about prebiotics is you tend to see pathobiont populations go down with their use as well as species that we tend to classify as beneficial like Bifidobacteria, Faecalibacterium. Their populations actually increased. You can see massive shifts with that.

If I've got that same patient to eat more fiber, we're still going have some nice shift to that ecosystem but you're not going to have that same thousandfold potentially increase in Bifidobacteria. There might be a slight increase because they might be enjoying some of the fruits of that fiber too, but they're not going to be selectively fed in the same way as with a prebiotic.

Dr. Adam Rinde: That's a really big point right there and helpful point because a lot of the patients I'm sure that see you would not tolerate just being loaded up with lots of fiber and the fact that you can step back and say, "Here's what I see is, something that's specifically going to help you" versus just taking an aim at the whole ecosystem with increasing fiber in the diet.

Dr. Jason Hawrelak: I agree. We were speaking before this recorded about the different patient sets we see now. I still recall the days I could be much broader with recommendations. They were generally healthier population base, whereas now we're seeing people that are often farther along in the disease process. So, you have to more gentle in targeting with how we approach.

Dr. Adam Rinde: People are looking for answers in their gut now more than ever, so they're coming to us with all chronic conditions not just irritable bowel syndrome or some constipation or diarrhea. This is a complex health condition and they're looking at their gut for answers.

Dr. Jason Hawrelak: That's been again brilliant looking at the research out there really looking at dysbiosis as a driver of primarily gut conditions to what we see now. Dysbiosis is a driver of anxiety, depression, obesity, type 2 diabetes, nonalcoholic fatty liver disease. There's very few Western diseases that I would argue that there isn't a degree, if not a lot of research that's built up around dysbiosis as a potent driver of that disease state.

Dr. Adam Rinde: You've already talked a little bit about this but I want to go deeper into certain controversies about probiotics. One of them I'm just going to put out there because a lot of people think that if you're deficient in certain microbiota or a certain genera in the microbiome that you could take a probiotic and it will fix it.

And so, I want to talk a little bit about your thoughts about that because there's some misconception or gray area around that and then just any other controversies that you like to bring up about probiotics.

Dr. Jason Hawrelak: That's a great starting point and that's what I would call the permanent colonization myth. I was taught this too as part of my naturopath training. That myth probably goes back to himself who believed that when we ate yogurt, the yogurt producing bacteria would take up residence in our gut.

This is going back to the early 1900s. So, there's a lot of history behind that mythology. It's sadly not of course based on research but you can look at the last 30, 40 years of clinical trials on probiotics and 95% of the time, there's no long term connotation with their use. If they stick around for a week to two weeks after cessation of these people that's very good and they do this follow-up test, you can see that it's there.

When they take it two days later, it's completely gone from that ecosystem and there's a tremendous body of evidence showing that same thing. So for probiotic researchers, this idea of colonization has been a myth for long time ago. It has been slow for this myth that you get out there so they do get people to do a test.

But actually here, I can just pop a supplement and I'll be colonized forever from this time point and that's not the reality of it. There's very few strains of Bifidobacteria and Lactobacilli that has been shown in research to stick around for any duration of time, and even then, it's been only a relatively small proportion of people that occurs that just might be the right environmental conditions but there's something unique about those potential strains as well.

So, we have to put paid to that one and that really shift your consideration in view of the microbiome too, because if you've got this idea that you can just hammer it, take tons of antibiotics and not worry about the consequences you can just pop up a high potency multi strain high CFU probiotics supplement that will recolonize your gut, then it cheapens. There's no appreciation for the complexity of that ecosystem and the fact that's not real. You're a custodian of that and it's not that simple.

You could do a fecal transplant but that's a whole new ballgame in terms of getting your head around if someone getting other people's poo in your system and that does have the capacity to recolonize in a much different way than current generation of probiotics. It's just that Lactobacilli and B