The Gut Health Podcast

The Gut Dictionary: Probiotics, Prebiotics and Postbiotics Explained.

• Kate Scarlata and Megan Riehl • Episode 23

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Dr. Mary Ellen Sanders, an expert in probiotic microbiology, helps us decode the often confusing world of probiotics, prebiotics, and postbiotics by explaining their scientific definitions, evidence-based benefits, and practical applications for gut health (and beyond). 

This episode has been sponsored by Activia.

• Probiotics are live microorganisms that confer health benefits when consumed in adequate amounts
• For something to be called a probiotic, it must be alive, defined to the strain level, and tested in the research setting for health benefits
• When selecting probiotics, look for products with strain designations and doses guaranteed through end of shelf life, not just "at time of manufacture"
• The US Probiotic Guide (usprobioticguide.com) offers independent assessments of probiotic products and their evidence levels, including specific conditions or symptoms
• Specific probiotic benefits include supporting gut function during antibiotic use, reducing respiratory infections, and decreasing crying in colicky babies
• Prebiotics are substrates (often fibers, but also polyphenols) that feed beneficial gut bacteria
• Research suggests about 5 grams of prebiotics daily may be beneficial
• Postbiotics are beneficial preparations of dead microorganisms or their components, challenging the notion that microbes must be alive to benefit health
• When trying probiotics, consult with your health care provider first, as there are some conditions in which they are contraindicated. 
• Multi-strain probiotics and synbiotics are commonly available but rarely tested in their exact formulations

References and resources: 

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Website: www.katescarlata.com and www.drriehl.com
Instagram: @katescarlata @drriehl and @theguthealthpodcast

Order Kate and Dr. Riehl's book, Mind Your Gut: The Science-Based, Whole-body Guide to Living Well with IBS.

The information included in this podcast is not a substitute for professional medical advice, examination, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider before starting any new treatment or making changes to existing treatment.

Kate Scarlata, MPH, RDN:

This podcast has been sponsored by Activia.

Kate Scarlata, MPH, RDN:

Maintaining a healthy gut is key for overall physical and mental well-being. Whether you're a health conscious advocate, an individual navigating the complexities of living with GI issues, or a healthcare provider, you are in the right place. Healthcare provider, you are in the right place. The Gut Health Podcast will empower you with a fascinating scientific connection between your brain, food and the gut. Come join us. We welcome you.

Dr. Megan Riehl:

Hello friends, and welcome to the Gut Health Podcast, where we talk about all things related to your gut and well-being. We are your hosts. I'm Dr Megan Riehl, a GI health psychologist.

Kate Scarlata, MPH, RDN:

And I'm Kate Scarlata, a GI expert, dietician, and today we're diving into the world of biotics, probiotics, prebiotics and postbiotics. You've probably seen these terms on yogurt labels and supplements or even health blogs, but do you really know what they mean? Are they different? Do you need all of them? Most importantly, how do they actually affect your digestion, your immune system and your overall well-being? We'll unpack the science, bust a few myths and give you some easy takeaways that can support your gut health for every day.

Dr. Megan Riehl:

So our guest today is going to help us with many of these answers. Dr Mary Ellen Sanders, welcome. She is a consultant in the area of probiotic microbiology. She works internationally with food and supplement companies to develop new probiotic products and offers perspective on paths to scientific substantiation of probiotic product label claims. She was the founding president and executive science officer for the International Scientific Association of Probiotics and Prebiotics, the ISAPP. You can check out very valuable information at www. isappscience. org. This is an organization devoted to advancing the science of probiotics, prebiotics, symbiotics, postbiotics and fermented foods. Through ISAPP, she participated in many scientific efforts, as reflected in her over 140 peer publications, and led many communication efforts in the biotic space. Dr. Sanders lives in Colorado with her husband, where she enjoys time with her two grandchildren hiking and riding her 26-year-old Morgan horse. Welcome, Dr Sanders.

Dr. Mary Ellen Sanders:

Thank you so much, Megan.

Kate Scarlata, MPH, RDN:

Love that you have a horse. I actually love horseback riding. I don't do it that often, I don't own one, but any chance I get to ride one I find it just the most peaceful, relaxing activity. So I love that.

Dr. Mary Ellen Sanders:

It's been a great hobby and I've really enjoyed sharing it with my grandkids and my daughter, of course, while she was growing up.

Kate Scarlata, MPH, RDN:

Yeah, that's awesome. Really enjoyed sharing it with my grandkids and my daughter, of course, while she was growing up. Yeah, that's awesome.

Dr. Mary Ellen Sanders:

So we're going to get right into the definition of probiotics. What is it? So? Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host, and this is a very broad definition. And it's important to realize that probiotics, even though we know them mostly in foods and dietary supplements, the definition is broad enough that it really encompasses not just food for people. So there are probiotic products that are made for agricultural animals and even some, for example, for my horse. You know you can buy probiotics for your horse, you can buy them for your pets. They're not just foods you mentioned dietary supplements already but they could also be potentially formulated into drugs, into medical products, and they're not just orally consumed. So, in addition to not being just foods, they could, for example, be applied as a probiotic on your skin. There's also some preparations that are intravaginal. So there are different ways that probiotics can be administered, and so I just point that out, because it is a very broad, all-encompassing definition.

Dr. Mary Ellen Sanders:

And one other point I think that we don't want to leave behind in this introduction to probiotics is how important it is that the microorganisms that are in a pro or that comprise a probiotic are defined to the strain level. And what that means is that you have a genus of a microorganism, a species, and then there's always a strain designation, because even within the same species you can have genetic variation that will identify different strains among the same species. So one popular probiotic is Lactocaceae bacillus rhamnosus GG, so the Lactocaceae bacillus, which incidentally used to be Lactobacillus, but the nomenclature changed. So Lactocaceae bacillus is the genus, rhamnosus is the species and GG is the strain designation. And then one last really important point about that definition is that these microorganisms need to be well-defined to the strain level, but they also have to be tested for a health benefit to be able to legitimately be called a probiotic.

Kate Scarlata, MPH, RDN:

Yeah, I think it's also confusing. Sometimes people don't realize they're alive. They have to be alive. You know what I mean. In your body they are alive. So when we're talking about, like, even fermented foods and I know they don't, we've had an episode on that If something's baked, it's not going to be a source of a probiotic because that microorganism has been killed. So when consumers are looking for a probiotic, what should they be looking for when they're selecting one?

Dr. Mary Ellen Sanders:

And that's a great question and it's quite difficult, I think, for consumers to weed through everything that's on the market that has the word probiotic on a label. You know just some tips for doing that. If you're looking for a probiotic in a food product, I think one helpful thing to do is to make sure that the product lists the strain designation on the label. And I was involved in a survey project with a colleague of mine and we looked at the different products in the refrigerated section of the grocery store and looked at what kind of information was given on the labels and what we found was the products that contain the strain designations were more likely to be able to be linked then to health benefits. So I think it's a good idea to just make sure that the company is putting the strain designation. That also says that they're being sophisticated about their approach to the field.

Dr. Mary Ellen Sanders:

You know they recognize that not all probiotics are the same. So that's just one hint I would throw out there. And I think if you're looking at supplements and it's not quite as common in food products, unfortunately, but make sure if you're looking for a dietary supplement, that it does show the dose that's in the product and, very importantly, the product should not say at time of manufacture. So the dose should not be at time of manufacture, it should be indicated to be through the end of shelf life, and so if the use by date on the product is there, you should be able to get the indicated dose all the way through that use by time. And so it's important to make sure that your product does not say at time of manufacture.

Dr. Megan Riehl:

Absolutely. You know it's so funny that and I want to hear more of these tips and tricks because you know now that we're doing this podcast and we've had really the benefit of having some amazing, world-renowned experts but I'm now getting more and more of my friends and family that they're like hey, it makes sense that a probiotic is at the pharmacy. But, exactly to your point earlier, I've had a friend reach out and she's like I was at my OBGYN, she's offering probiotics. Does my vagina really need a probiotic? And it's like it feels like there is something for everything these days. So to hear you bringing up all the products that are available, these tips and tricks are so helpful.

Dr. Mary Ellen Sanders:

Good, you know.

Dr. Mary Ellen Sanders:

One other tip I will give your listeners is that because again it is so difficult to wade through you know the type of evidence that's available for a specific strain that's listed on a label.

Dr. Mary Ellen Sanders:

There is a guide out there and it can be found at www. usprobioticguide. com, and this is a guide that is updated yearly and it lists products available in the United States and what it does. That's different from pretty much any other resource you have out there is. It specifies products and it tells you what strains are there, what the dose is and what the tested evidence is for, and so it's really worth looking at and if you can find products on that list, at least you know that a group of independent reviewers said that there was evidence to show that this product was tested for that benefit. But what I would caution you about that guide is that it includes three levels of benefit. It has level one evidence, level two evidence and level three evidence, and I would pretty much ignore the level two and three evidence and just go with products that have level one evidence, because it starts getting pretty. The level of evidence once they get to the level three is not that strong.

Kate Scarlata, MPH, RDN:

Okay, I think that's really important and that's what I tell my patients. That strong Okay, I think that's really important and that's what I tell my patients If they're coming in with constipation. I'm going to try to find evidence for a probiotic strain that helps with constipation, right? So it's not necessarily like lactobacillus. What is it? Kci whatever the new nomenclature.

Dr. Mary Ellen Sanders:

The new name is lactacta Caseyi Bacillus. I know it's such a mouthful, I know.

Kate Scarlata, MPH, RDN:

It is a mouthful, my goodness so. But you do want to like select the right one for the right indication, and I think that's why a health professional can be a good guide and you know certainly online guidance as well but think about why you're taking it and then see if there's an indication for a specific probiotic strain, for that indication.

Dr. Mary Ellen Sanders:

And I do think another important point is that people will be their own determiners of a success, and you know, what we sometimes fail to communicate well, I think, is that you know, we do these research studies. They are all composed, or at the end of the study, what you have is aggregate data, and within that aggregate of data, there are all composed, or at the end of the study, what you have is aggregate data, and within that aggregate of data, there are always responders and non-responders that then get averaged out into the whole thing, and we are at a point in the field where we don't understand what really drives response and non-response to certain probiotics, and that's certainly true in the medical field, with drugs as well, and so I think people can be their own titrators of is this working for me or not?

Kate Scarlata, MPH, RDN:

I love that advice. I mean, we think our gut microbiome is personal to us, so why wouldn't our response be a little bit different, right? We're all different genes, different microbiome. I love that advice.

Dr. Megan Riehl:

So if we've been on something for three years and you still are constipated, probably not the right probiotic for you.

Dr. Mary Ellen Sanders:

Right, exactly, and in fact I will say, without any evidence for saying this. I will usually tell people who just ask me at a party what should I do, and I'll say try it for a month and if you see no benefit then try something else. Maybe probiotics aren't going to be a solution, or maybe you've got the wrong strain.

Dr. Megan Riehl:

That's perfect. This kind of leads into our next question here Should we all be using probiotics? Are there adverse effects to using them? Let's start with that.

Dr. Mary Ellen Sanders:

Well, the adverse effects is an excellent question and I think sometimes in the food and dietary supplement world we forget to ask that question and we need to realize that products that are on the market as foods and dietary supplements are designed you know, it's a legal category of product to sell in the US and they're designed for the general population that's generally healthy, and so if you have underlying health concerns, you have to recognize that these products have not necessarily been tested and shown to be safe in whatever condition you happen to have. Now, having said that, there's been many clinical conditions that have been tested for probiotics, but nothing is ever 100% safe. We have to recognize that. But I will say, with the standard probiotics the lactobacillus umbrella probiotics, the bifidobacteria, the saccharomyces and some other genera that have been used for a long time we see really good tolerance for those and there are very few side effects associated with them. But again, if you're severely immunocompromised or if you have some other underlying conditions, you for sure check with a medical professional before engaging in them.

Dr. Megan Riehl:

Okay, let's say I'm in my 40s. I eat a pretty wide range of fruits and vegetables. My bowel habits are typically pretty normal. I have the stressors of being a working mom. Do I need a probiotic?

Dr. Mary Ellen Sanders:

There's very little evidence to say that yes, you do. That's just not really how the studies have been done. I think I was involved in another project not too long ago. We really looked at the literature in certain areas for certain clinical indications for probiotics and we asked the question like is there convincing evidence that healthy people should take a probiotic? And the end of our assessment now keep in mind, we used a very high level of evidence. In other words, we were approaching this as if we were the United States, the US Preventive Services Task Force, who makes recommendations on you know, recommendations for healthy people and they say what you can recommend and what you isn't there yet to really substantiate that you're going to necessarily benefit if you have no underlying concern that you're trying to address.

Dr. Mary Ellen Sanders:

I do think that there's emerging evidence to suggest that adding live microbes to your diet may provide some benefit, and those could come from fermented foods, those could come from probiotic foods or supplements. But you know, I think the way to look at probiotics is to really focus on where the evidence shows that they seem to be beneficial, and I think probably top of the list is to support gut function during antibiotic use. You know it helps to decrease symptoms associated with antibiotic use. There is some good evidence not excellent evidence, but good evidence to show that it can reduce the risk of respiratory tract infections and again, I'm saying this very generally. Obviously there are certain strains that have been tested for these conditions. Another one that I think is very interesting with your potential stressed mom, is that there's really good evidence I would say this is very high level evidence that one specific strain of lactobacillus reuteri can reduce crying time in colicky breastfed babies.

Dr. Megan Riehl:

And that's a great one actually.

Dr. Mary Ellen Sanders:

Then we also, you know, to allude to the further point I mean sorry, a previous point that was made is that there's reasonable evidence that you can reduce vaginal and urinary tract infections in women with using probiotics, evidence that you can reduce vaginal and urinary tract infections in women with using probiotics. And there are some digestive complaints like constipation, bloating, those types of things that I think it can do, and so, you know, those are the areas that I think I would focus on. But, again, if you have some reason that you have a concern, then you should be able to find out if it's working for you or not. Right, If you?

Dr. Mary Ellen Sanders:

take a probiotic so there's very little harm in taking a probiotic and seeing if it.

Dr. Megan Riehl:

Well, I would have loved that probiotic about eight years ago with my firstborn you had a colicky baby, so did I yeah.

Dr. Mary Ellen Sanders:

I think it reduced crying time by about an hour. I can't remember an hour per day or something like that, and I'm thinking that's such a wonderful endpoint to study because people don't care how many lactobacillus reuteri you have in your gut or they don't.

Dr. Megan Riehl:

You know, they don't care about any of that.

Kate Scarlata, MPH, RDN:

Like my baby's not crying as much. That's a good one.

Dr. Megan Riehl:

Yeah, that's a good one. Yes, I know my mental health probably would have been better at that point if I had less crying and more sleep. So let's turn to your thoughts on this term psychobiotics. What does the science tell us about these?

Dr. Mary Ellen Sanders:

Well, first of all, personally I'm not a fan of the term Okay. I say that only because there's just so many terms that people throw out there, and I think it causes more harm than good. I think people get very confused about what do all of these? You see immunobiotics, you see psychobiotics. You see pharmabiotics. You see immunobiotics. You see psychobiotics, you see pharmabiotics. There's all these different terms and they aren't robustly defined.

Dr. Mary Ellen Sanders:

And you know, I would much, rather, much, much rather have someone say we have a probiotic that has been studied for mental health issues or brain function or whatever, and that's my own personal bias. I do think that this is a really interesting evolving area. We're not there yet to be able to strongly say that these specific strains are going to show big benefits for anxiety or mild depression or issues like that. But there are a few studies that have been conducted that show signals. You know that, show that there might be something there. Great animal research show signals, you know that, show that there might be something there.

Dr. Mary Ellen Sanders:

Great animal research, great preclinical research, is behind a lot of this. But I think the translation of that research into humans has been tough to do and I think we lack high quality, properly powered human trials to really get at this. And I will say you know those trials are expensive to do and until we better understand mechanisms and things like that, it's really hard to know who's going to benefit, who's not, as we mentioned earlier. So it's hard to know who to recruit into your study in order to give yourself a chance of really seeing a better signal. But I think it's a very exciting area and again, I know there are some products on the market already with those endpoints. You can give them a try and if they work for you, great.

Kate Scarlata, MPH, RDN:

Yeah, we're just not there.

Dr. Megan Riehl:

We're not there yet, and you know, so often there's still a lot of stigma around taking medication, pharmaceutical medication for mental health, and we see this similarly in gastroenterology patients, right. So you know, I think, that they oftentimes would rather try a prebiotic than a pharmaceutical, and so this again may open some doors for people in the mental health space for additional options. But our takeaway today is the science just isn't there to yet totally replace your SSRI or your neuromodulator.

Dr. Mary Ellen Sanders:

Well, and I think the other point that you alluded to but didn't say overtly was the medications that do exist can be laden with serious side effects.

Dr. Mary Ellen Sanders:

That's right, you know these are not medications that are just take it and you never, you know you see a benefit or nothing at all. They might be that you see a benefit, but you also see some real downsides to them, and that's where I think probiotics really have. You know, there's a door open there because we don't seem to see the adverse effects associated with taking them, and that's because they're acting mechanistically in different ways than these other drugs are, and so I think there's real potential there and I hope that that continues. I know there's so many good scientists interested in this area. You know we'll make some progress.

Kate Scarlata, MPH, RDN:

Yeah, definitely, it is very interesting. And again, when you think back, you know the gut and brain and microbes creating neurotransmitters and how does that all make out in this probiotic, psychobiotics or whatever we want to call?

Dr. Mary Ellen Sanders:

them.

Kate Scarlata, MPH, RDN:

We're going to call them probiotics for gut brain health. That's what we're going to call it.

Dr. Mary Ellen Sanders:

Either that or just make sure you define what you mean by your term.

Kate Scarlata, MPH, RDN:

I hear you. I think it is very confusing for the consumer to hear all these different terms and what the heck they mean. So I think, keep to probiotic, but then qualify what it's for. So we're going to switch to prebiotics, so I'd like to hear the definition of prebiotics. And then, where are we finding these prebiotics?

Dr. Mary Ellen Sanders:

Well, I'll start with the scientific definition of prebiotics and then I will go from there. A prebiotic has been defined as a substrate that is selectively utilized by host microorganisms, conferring a health benefit, and that's a big mouthful. But, in short, what that really means is that prebiotics typically serve as food for the beneficial microorganisms that reside in your body. Okay, and like probiotics, they also have to be tested and shown to have a health benefit. So just because we have a soluble fiber that you can show that might have some impact on gut microbes, we won't call that a prebiotic until someone does a study and shows some endpoint that's been improved by consuming it. If that makes sense, yeah.

Kate Scarlata, MPH, RDN:

It totally does. I love that this conferring, that's the big word, conferring it's confers.

Dr. Mary Ellen Sanders:

I was on the panels that came up with these definitions, and it's a lot harder to do than you might think, because every single word has a meaning and you have to make sure it's not going to be misunderstood or somehow have a separate meaning that you didn't intend.

Kate Scarlata, MPH, RDN:

Exactly, exactly, but it just it does kind of crack me up. So when we think about prebiotics, you know I know this definition's changed a little bit over the years because I've been in the science for a while and you know kind of was always about carbohydrates as being sort of a prebiotic, and now it's kind of slid into polyphenols and maybe some other food components too that can act this way. Can you just touch on that a little bit?

Dr. Mary Ellen Sanders:

Yeah, you're absolutely right. Initially they talked about them being carbohydrates and then usually fibers, and typically soluble fibers, and so it was a very, very specific kind of a box, a chemical structure box, that they were putting prebiotics in initially. The way the field has gone is that they started recognizing that. Maybe the value here is to look at what we're looking at in terms of mechanism of action, like what substances can be utilized by the microbes in your gut and then have some changes that are in your gut microbes and then can that lead to a benefit? And what we found is it's more than just soluble fibers that can do that. And I am far from an expert on polyphenols, so I'm not going to say much at all about them. I know that they're very, very interesting compounds. They've got antioxidant properties. They have all these properties that are beyond just their ability to be utilized by the microbiota. I think that's a very exciting area that will be developed, but you're right.

Kate Scarlata, MPH, RDN:

You don't have to be a carbohydrate anymore to fit into the prebiotic category. Yeah, which is great, because you know we see these polyphenols in a lot of fruits and vegetables extra virgin olive oil, so you know some good things.

Dr. Mary Ellen Sanders:

And I think that one of the things that we did keep in mind as we were developing definitions is that we really wanted them to be broad enough to encourage innovation. You know, we didn't want to paint these substances into a box that wouldn't allow the clever scientists of the future to be able to think of something that we wouldn't have anticipated, right.

Kate Scarlata, MPH, RDN:

Yeah, that's excellent. So what do you think? Should we be getting prebiotics from a supplement, or do we get them from food, or as a mix? What's the jury?

Dr. Mary Ellen Sanders:

I am a big food person, you know, try to get your dietary needs met through food rather than supplements. But what I will say is that most of the studies done in prebiotics have been done at levels of about five grams or more per day, and that's tough to get out of foods. The other thing you have is we always talk about onions and garlic, and maybe bananas have a few prebiotics in them and, you know, maybe a Jerusalem artichoke if you can find that in your grocery store, right. But you know it's not that easy to find the food sources and be able to eat enough of them where you're going to get the benefits that have been shown in these studies and I think that's where the supplemented foods come in. It does at least allow you to tap into a product that reflects the evidence that was developed in a controlled human study.

Kate Scarlata, MPH, RDN:

So you brought up a lot of foods and, being a GI dietitian, the foods that you brought up are fructans primarily, and those are a known prebiotic. But what about galacto-oligosaccharides in beans? Is that controversial?

Dr. Mary Ellen Sanders:

No, I don't think it is, and it's interesting you say that, because when I think of the top line foods that always get thrown out there about where do you get your prebiotics, you know it's always the ones that I already mentioned. Beans are certainly a great source of fiber, and fiber is wonderful. I mean we don't eat enough of it. We know that. You know, if you more beans, well I can't say the more beans the better, but I mean you know those are all great foods, to the extent that they're. What levels of prebiotics? Unfortunately, I just don't know. I'm sorry.

Kate Scarlata, MPH, RDN:

That's okay, I'm just curious. I was just curious because they were mostly fructan sources and when we look at supplements they're also fructans, so it's inulin chicory root extract.

Dr. Mary Ellen Sanders:

Those are the ones that you're seeing mostly, yeah you do see galactooligosaccharides, but I don't know the commercial names for those either. But the GOS is definitely around as well. But you're probably right, you're more familiar with the products actually than I am on those. But yeah, but goss is. I think there's a lot of evidence on GOS as well, and yeah.

Kate Scarlata, MPH, RDN:

If you can stand the farting and the gas, well, that's the thing. Yeah, go, gentle go, gentle.

Dr. Megan Riehl:

I was going to beans. Beans, the magical fruit. The more you eat the more you toot.

Dr. Megan Riehl:

We say that a lot at the Riehl House. There's a lot of tooting and that's okay.

Sponsor:

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Dr. Megan Riehl:

You mentioned five grams in the research. Is there a gram amount per day of prebiotics we should be aiming for in adults.

Dr. Mary Ellen Sanders:

That's what you're looking for is the five grams. If you want to tap into the benefits, I should say five grams per day. If you want to tap into the benefits that have been studied, five grams per day. If you want to tap into the benefits that have been studied. That's pretty much how they've been studied. But we have to keep in mind that the research is just so piecemeal that you know no one's done a study on six and a half grams or you know what I'm saying.

Dr. Mary Ellen Sanders:

Like we don't really know, or probably four and a half grams. Like we know that in the studies done there's zero, there's five grams, there's 10 grams and I'm making this up, but you know what I mean. Like you have these very distinct amounts that have been tested and the evidence isn't so broad that we're really clear on exactly what the doses are, and not all prebiotics are the same, and so it depends on if you are doing your study on fructooligosaccharide versus a galactooligosaccharide versus a polyphenol, and you know it's just really hard.

Dr. Mary Ellen Sanders:

So I just know, when I've pressed the prebiotic, people that know this literature way better than I do, you know the five grams is what they come to, is like they're just, and I think that that comes from that. There just haven't been studies conducted that have shown benefits below that.

Kate Scarlata, MPH, RDN:

Yeah, and I just want to interject quickly here because there's really interesting emerging evidence in IBD looking at fructans in a subset of patients being inflammatory. So I wonder just again to this personal nature of even prebiotics, and we see in IBS patients that fructans are a common, common, common trigger to their GI distress. So again I would just say you know, work with your healthcare provider. Listeners, because we've been studying this for a long time, but still it's still really kind of in its infancy and it's not going to be a one size fits all.

Dr. Mary Ellen Sanders:

No, but I do think what's interesting about a prebiotic and I don't think we have this robust of evidence with probiotics in that dietary fiber there's a lot of evidence and a lot of consensus that that's a good thing. And prebiotics many of the prebiotics fit into that and so to the extent you get one or two grams of a prebiotic along with your other fibers that you're getting through your diet, I just can't help but think that that's a good thing, absolutely. With the fibers I don't worry quite as much about hitting the exact dose on the nose.

Kate Scarlata, MPH, RDN:

Yeah, I think fiber is important.

Dr. Megan Riehl:

It's an umbrella term, so there's going to be so many different types of fibers and it's, you know, listening to your body, but yeah, fiber, but we're going to go to postbiotics. What is it? Has this term been sufficiently defined yet, or is it a moving target at this time? Talk to us about where we're at right now.

Dr. Mary Ellen Sanders:

So postbiotics are a fairly recent concept. The term's been around for over a decade but it's really kind of coming to a head now because of some new research that's been underway and has been completed on postbiotics and so you're going to start seeing the term more. And what a postbiotic is is a preparation of inanimate microorganisms and or their components that confers a health benefit on the host. It confers a health benefit on the host. Now, to break that down into easier language, I think what we consider a postbiotic is to be a preparation of dead microorganisms and the microorganisms may either be intact dead microorganisms or they may be cell components, so the microorganism may have been broken apart through some kind of treatment that the preparation underwent, and the preparation may or may not contain microbial metabolites or other microbial end products. And so we're looking at kind of this combination. It's not a purified preparation in the way that you might get purified butyric acid, for example, or something like that. It's really a combination of the microbes or their components and they may have cell fragments, they may have metabolites and other things thrown in.

Dr. Mary Ellen Sanders:

And I think that when you ask about is the definition established? I think the definition that I just gave you is a fairly clear definition. We have a very clear paper out that talks about it, but I will say there's not consensus on that. So I think that what we're seeing in the marketplace develop and this is the research I alluded to some very interesting studies that have looked at heat killed microorganisms and showing that they have health benefits, and that's a game changer when you start realizing that these microorganisms, once they're dead, are not necessarily inert. Okay, that's an important difference. But where there's lack of consensus is that some people want to say that the metabolites that are produced by the microbes in the absence of the microbes could also be called a postbiotic, and we disagree with that. At ISSAP you mentioned them early on in the podcast. You know our definition was is no, what's key to a postbiotic is to have the microorganism present, with or without those metabolites.

Kate Scarlata, MPH, RDN:

And so that's where I think we still need to sort it all out in the field. Yeah, because I was just reading a paper from the Stanford group and they were really kind of muddying that definition a little bit, because I've always followed what you've put out and then their paper was a little bit different, you know, talking about like sourdough itself having postbiotics.

Dr. Mary Ellen Sanders:

Right and we can get into that. Do you want to get into that right?

Kate Scarlata, MPH, RDN:

Now, well, first, yeah, where do we find these postbiotics? I know there's some preparations out there that have been studied for IBS, for instance, so I think it's really interesting in a supplement form. But you know just in general where do we find them, and then just maybe talk through the fermented food piece.

Dr. Mary Ellen Sanders:

Postbiotics. I think what's important to realize is that just because a microorganism is dead doesn't make it a postbiotic, right. So you have to then go to that last part of the definition about doing a study that shows that it confers a health benefit. Okay, so the postbiotics that are on the market I am not up to date or I'm not aware of exactly what's on the market right now. I don't know who's marketing what in this area and putting a postbiotic term on it. My guess is you can find all kinds of things labeled as postbiotics that would not meet the definition and, unfortunately, you might find all kinds of things labeled as postbiotics that don't have strong science behind them, and we don't have guides in this area yet. I think it's a really emerging field. So any product that you're looking at that says postbiotic, I guess I would dive deeper and find out. Well, what studies are they claiming that substantiate a health benefit that would justify my interest in their product? Basically is what I would do.

Dr. Mary Ellen Sanders:

But to get to the fermented foods, I think the important point here is that sourdough bread is a great food. Like we all love sourdough bread, we all love our fermented products, and I can lead a parade on that topic. I love them. But just because sourdough bread is a great product doesn't mean that it's providing postbiotics. Is it providing you dead microorganisms? Yes, has anyone done a study showing that the dead microorganisms that are the component of sourdough bread actually lead to a health benefit? So, in other words, do you have a controlled study that has a sourdough bread that was made, maybe with baking sodas? You know some sourdough compared to the actual sourdough you know.

Dr. Mary Ellen Sanders:

Have you established a health benefit, you know, in any kind of rigorous study? And I don't know the study that's done that. So I would not use the term postbiotic to describe sourdough. I would not say that sourdough is a source of postbiotics.

Kate Scarlata, MPH, RDN:

So even though it's and I agree with you, I mean I've read the definitions that have been put out I just want to like clarify this for our listeners. So you have your sourdough and you look at it in a lab like I know that they've looked at some of these end products in the bread and there's butyrate in it Still not a postbiotic, even though we know butyrate could be. The strain isn't characterized or the health benefit hasn't been proven. Like, just walk the listeners through that a little bit.

Dr. Mary Ellen Sanders:

First of all, I'm not sure I don't know how beneficial the amount of butyrate in a bread is going to be for you, and you know this better than I. Isn't butyrate going to be pretty much absorbed in the proximal small intestine? I mean, it's not making its way through your body. It's basically going to be an energy source, right? So butyrate that's produced in situ in the gut is great. It fuels your epithelial cells. I mean that's great.

Dr. Mary Ellen Sanders:

But that's very different than consuming butyrate, right, right, okay, so I think that would be a question that I would have about that claim to a benefit. But you're right, if there's solid evidence that some microbial metabolite causes a health benefit on its own and has been studied on its own and it's present in the bread, then I would say, yes, that sourdough bread. You could reasonably make the case that that sourdough bread would deliver that benefit that's associated with whatever it has. Would I call it at that point a postbiotic man? I don't know, I'd have to think about that. I would have to think about that because, again, the postbiotic is a preparation of these microorganisms which the sourdough reasonably could be, and if you could, then it's killed in the oven, it's heat killed and you know that there's a benefit associated with a component.

Dr. Mary Ellen Sanders:

Then yeah, I mean, it's a little edgy there, right, I think you probably could make the case, then I don't know that you would necessarily have to do the study on sourdough, but you know we talk about this a lot. With all the biotics is the method of delivery important. So can you take that lactocacy ibacillus rhamnosus GG, which has been studied in, you know, across a variety of formats, across a variety of clinical endpoints, and just throw it into whatever you want to throw it into and claim that same benefit, and a lot of people do that. I mean, that's a lot in the marketplace, but people question that, and so I think that's what these things might raise. But wow.

Dr. Megan Riehl:

Well, our listeners just got a front row seat to what these consensus meetings can look like, where you put, you know, 15 to 20 experts in the room, sometimes, you know, asking in these thoughtful ways, these questions on definitions, and you each have your own experience with this, and so it is it's fascinating for me to listen, and kind of have this front seat, to the two of you talking about this concept.

Kate Scarlata, MPH, RDN:

Well, I think we have to stay curious, right and learn from one another. And then that's when things evolve and change, which is, you know, exciting for sure, right.

Dr. Mary Ellen Sanders:

No, and it's a great question, you know, it's one that the field has to answer.

Dr. Megan Riehl:

Yes, I have one last question that I'm just now thinking more and more so the concept of a symbiotic is a probiotic and a prebiotic together. Can you just give hey, I'm a one-stop shop kind of girl, if I can a quick thought on these and how our listeners may benefit from some of these products?

Dr. Mary Ellen Sanders:

Yeah, symbiotics, that's a great definition really. We would define it with a lot more words, but essentially you're right pro and prebiotic. And the complication with synbiotics is I think there are two ways to consider them. One is is just a product that delivers two functional ingredients. You know that you have the pro and the pre together and they don't necessarily have to interact with each other. Another is is that the prebiotic is paired with the probiotic, so that the prebiotic actually, once you consume them, is the food for the probiotic, and so in the absence of the prebiotic in the symbiotic, the probiotic isn't necessarily going to do what it needs to do. Does that make sense? And so that's a much more sophisticated formulation of a symbiotic, and I don't think we have any on the market that actually do that.

Dr. Mary Ellen Sanders:

What we have on the market are combinations and the ideas to deliver two functional ingredients. I don't know that we would know they don't interact, but we don't have evidence that they do, that. They're just kind of functional in their own regard.

Kate Scarlata, MPH, RDN:

Okay, so you bring up a good point and this is going back a little bit to a comment a moment ago but there's so many products that might have known probiotics and they put three of them together but that product of those three have never been tested. That happens all the time. Daughter sent me a probiotic from one of her friends asking me what I thought about it and I said well, all three of these have known probiotic. They're strain level classifications, but I don't know how they're all working together. In that pill. There was nothing on the website and this is happening all the time. Can you just comment for our listeners, because it drives me a little bit nuts and I bet it was expensive, very expensive.

Dr. Mary Ellen Sanders:

Yes, I mean, in an ideal world, if we didn't have limited resources, all of these products would be tested as formulated, at the dose, with the combinations that they have. And that's just not the reality. And this is what I would call kind of the ingredient approach to probiotic formulation. So you've got a very strong research base, let's say on the L. rhamnosis GG. You've got a strong research on . They do different things. Let's combine them and just give those to our customers and do you expect the benefits from both of them to be present once the person consumes them? And we've thought about this a lot and in fact in the show notes we can maybe reference one of the papers that we put out addressing this issue. And I guess there's two ways to look at it. One is is no, we don't have evidence that they are necessarily delivering the same benefits they would alone.

Dr. Mary Ellen Sanders:

I think that you can go at it from the other way, saying would we reasonably expect that those benefits would be neutralized by combining them?

Dr. Mary Ellen Sanders:

Yeah, right, and the more we thought about it, what we kind of came to the conclusion of and again, there's no guarantee on this, but it's like can you come up with a solid scientific rationale is that when you consider that these things are taken, you've got a mixed diet. It's going into your stomach with food and all these other things and then it's ending up in your gut with trillions of other microorganisms. Like, does it really matter that you necessarily have combined these two together and aren't they going to hit the gut or hit the small intestine, wherever it is that they have their effect and likely be able to do what they would normally do? And that's kind of where we landed on it, which is it would be harder we think it would be harder to you can never prove a negative but it would be harder to really come up with a solid reason why you would expect them to negatively interact and not deliver the benefit. All right Is kind of where we ended it up, but it's you know.

Kate Scarlata, MPH, RDN:

Complicated.

Dr. Mary Ellen Sanders:

Well, it's complicated and we find ourselves so often in this field, lacking the studies that allow us to robustly answer these questions, so we just kind of try to make our best guess.

Dr. Megan Riehl:

All right, we're going to do something called a speed round with you today and we'll go through these as quick as possible, and I think this is the case. We want to use your brain, your knowledge. We know we could probably argue on both sides, but we just want to hear what your answer is. But we just want to hear what your answer is. And so, okay, we'll move through quick. Prebiotic, probiotic sodas Are these gut heroes or overhyped?

Kate Scarlata, MPH, RDN:

I'd say overhyped Love it. How about kombucha? Gut hero or overhyped?

Dr. Mary Ellen Sanders:

I mean it's a good source of live microbes, but I'd say overhyped.

Dr. Megan Riehl:

Okay, Morning or night best time to take a probiotic?

Dr. Mary Ellen Sanders:

Whatever time that you're more likely to take it.

Kate Scarlata, MPH, RDN:

Good answer

Dr. Mary Ellen Sanders:

Showing that any particular timing is better than another.

Kate Scarlata, MPH, RDN:

Okay. What about probiotics during or after antibiotic use?

Dr. Mary Ellen Sanders:

I think best to take it with your antibiotic. Okay, the studies are typically done that way and you know, so just go ahead and take them. The worst that happens is the probiotic doesn't survive as well as it might once you stop. But most of the studies have been have co-administered them and then try to use one that's been tested for AAD or for antibiotic associated diarrhea.

Dr. Megan Riehl:

Okay. Are expensive probiotics better than less expensive probiotics, yay or nay?

Dr. Mary Ellen Sanders:

I would say not necessarily. But I will say research is expensive, so a responsible company is going to have to recoup their investment. But that does not mean that irresponsible companies can't sell very expensive products.

Kate Scarlata, MPH, RDN:

Okay, confusing out, there. Are refrigerated probiotics more effective than shelf-stable ones?

Dr. Mary Ellen Sanders:

I don't think you can say that out of hand. There's been a lot of technological development where they remain stable at room temperature now and you certainly don't want to get them hot. They will die as the temperature starts to climb, but if you can keep them at room temperature, a lot of them are stable.

Dr. Megan Riehl:

All right, and our final question should we consider these products for long-term or short-term use?

Dr. Mary Ellen Sanders:

Well, one thing I didn't get a chance to say I'll bring up now, which is absence of evidence is not evidence of the absence of any benefit. So what I mean by that is is I keep saying, and you keep saying, that we need more studies, but just because we don't know that we don't have evidence that things work, doesn't mean that they don't work, and so that's why you have to be your best advocate, and so if you find, over the course of a year, that you're feeling a lot better you started out taking a probiotic and you're sustaining it and you like it I would say go for it. I think most of the research on probiotics, though, is focused on more short-term types of indications.

Kate Scarlata, MPH, RDN:

Okay, so we ask all of our guests what they personally do for their own gut, health and well-being. So we'd love for you, outside of horseback riding, which sounds wonderful and probably great for your gut, what else do you do?

Dr. Mary Ellen Sanders:

Well, I don't have anything really clever to say about that. I mean I try to eat higher fiber foods and I try to eat whole grains and fruits and vegetables, and you know it's always a struggle to eat well, but I think that's the smart way to do it. But I mean overall health. Of course you have to live a life that you can be grateful for and you have to keep your sense of humor right and express love to people that you love, and you know all of those things I think might be just as important and I've said already I'm a big fan of fermented foods. The evidence is not strong right now that it really matters that we deliver unknown microbes in large amounts to our gut, but it sure seems a lot of populations have done this for many years and you know not many years, I mean for millennia and it seems like it could be a good thing to model, but we don't have the data to be confident in that.

Kate Scarlata, MPH, RDN:

I think that was a great answer.

Dr. Megan Riehl:

Yeah, lots of endorphins coming from relationships and food, so that's a pretty perfect place for us to wrap up today. We thank you so much for your time, Dr. Sanders. We certainly have provided a lovely Gut Dictionary for our listeners and we are going to wrap up for the day, so thank you so much for joining us and thanks for all of your expertise. Thank you so much for joining us and thanks for all of your expertise and to everyone out there, thank you so much for liking, subscribing, sharing The Gut Health Podcast. We appreciate your support, our friends. Thank you for joining us as we grow this gut health community. We hope you enjoyed this episode and don't forget to subscribe, rate and leave us a comment. You can also follow us on social media at the Gut Health Podcast, where we'd love for you to share your thoughts, questions and experiences. Thanks for tuning in, friends.

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Kate Scarlata

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Megan Riehl

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