Gut microbiome and Plant-based diets (Part 1): How eating more plants helps you lose unhealthy weight, improve your metabolism and increase resiliency to mental stress - with guest Marcel van de Wouw, PhD

In Episode #7 I interviewed MarceI van de Wouw, PhD and we discussed how eating a plant-based diet can positively impact your gut microbiome. We also talk about the ways in which the gut microbiota influences your health; like losing weight, improving metabolism and  decreasing the negative effects of mental stress. 

In this conversation we also discussed:

- Marcel’s journey to becoming plant-based. 

- The by-products made by your gut microbiome and how they communicate health in your body (e.g. short chain fatty acids or SCFAs)

- The microbiota-gut-brain connection and how stress can negatively impact your microbiome (and vice versa!). 

- Strategies to improve your gut microbiota with plants and fiber. 

- Research that demonstrates the benefits of eating a fiber rich plant-based diet and how vegan diets make some of the biggest changes.

Resources:

- University of Calgary Psychobiology Developmental Lab: IG https://cumming.ucalgary.ca/labs/developmental-psychobiology/people/current-team

- Vegan Diets and Gut Microbiota research: https://pubmed.ncbi.nlm.nih.gov/35071294/

- Vegan diet intervention research: https://pubmed.ncbi.nlm.nih.gov/32987642/ and https://pubmed.ncbi.nlm.nih.gov/31292752/

- Research on how plant-based diets may influence the gut microbiota (e.g., increased fiber intake): https://pubmed.ncbi.nlm.nih.gov/31058160/

and https://pubmed.ncbi.nlm.nih.gov/32098430/

- Many of these fibers are broken down by the gut microbiota into a type of compounds called "short-chain fatty acids", which have been linked to energy metabolism, gut health, the immune system, how resilient we are to stress, and even mental health. A review on the topic: https://pubmed.ncbi.nlm.nih.gov/27259147/ and https://pubmed.ncbi.nlm.nih.gov/32521538/

Want to support the show? Help us by subscribing and leaving a review on Apple podcasts or wherever you listen to your podcasts. It only takes a few minutes and helps more people find the episodes.

About your host: Dr. Travis Cox - BA, DC, MSc is a Doctor of Chiropractic with a focus on Functional Medicine and plant-based nutrition. He is the creator of PBandHealthy.com and host of the Plant-Based and Healthy podcast. Connect with him on Instagram, Twitter and Facebook @yourvegandoc #pbandhealthy. And remember, individuals inspire and communities create change!

Transcript

Dr. Travis Cox (host):

Welcome back, listeners, to another episode of Plant-Based and Healthy. On today's episode, we have a special guest, Dr. Marcel van der Wouw, who is a postdoctoral fellow at the University of [Calgary 00:00:12] in the Developmental Psychobiology lab. His research focuses on the impact of stress on brain development and mental health during [inaudible 00:00:20] life, and the role that microorganisms in your intestines, i.e, the [gut microbiota 00:00:25], play in this relationship.

Marcel van der Wouw, PhD (guest):

We should care about these different microbes is because they have a huge influence on our healthy living from that perspective. And thinking specifically about diet as well, is all the food that we eat goes into our gastrointestinal tract. And a lot of these nutrients are sort of broken down and changed into the next metabolite or next nutrient that a body uses and uptakes. So for a lot of very specific nutrients, these microbes sort of form this bridge between diets and our health, which really emphasizes why it's so important that we care about these microbes.

Dr. Travis Cox (host):

Further understanding this topic allows us to make more efficient gut microbiome supplements, such as probiotics and prebiotics, to better support mental health. Welcome to the show, Marcel.

Marcel van der Wouw, PhD (guest):

Thank you. Thank you so much for having me.

Dr. Travis Cox (host):

Yeah. So I understand that you've recently been transitioning to a more plant-based lifestyle. So just take our listeners through your experience and journey in that transition to being more plant-based.

Marcel van der Wouw, PhD (guest):

Yeah, as with any sort of major dietary changes, sometimes we found it a bit difficult initially. What we tried to do is just switch in one go altogether, but we found that, that was difficult to adhere to for a long period of time. And I can imagine for some people it's a lot easier to adhere to. And then what we started doing, especially over the last few months, is do a more sort of slow transit where we're really focusing just on increasing more plant-based protein sources as well. So I've really tried to make a point of making sure that we have tofu, for instance, each week and try to improve the recipe and the taste of it so that we can really make these day, week by week improvements so that we can really get there. But yeah, it has been a journey and a good bit of trial and error, but it's exciting.

Dr. Travis Cox (host):

Absolutely. So it sounds like more of a recent transition. And what's your experience been like? Is it challenging? Is it just sort of learning the rope, so to speak?

Marcel van der Wouw, PhD (guest):

I think the sudden switch was very challenging, also because there's a lot of different recipes that you have to switch as well. And it just makes for a huge change, which can be difficult if you're both working as well. But sort of the recent week to week changes have been a lot easier, given they're not extremely fast, but to some extent, any little bit of progress is progress made anyway so...

Dr. Travis Cox (host):

Totally, little baby steps in the right direction and take your time, don't rush into it and if you do, it probably feels like too much.

Marcel van der Wouw, PhD (guest):

Yeah.

Dr. Travis Cox (host):

Awesome. And if you don't mind me asking, what motivated you to decide to become more plant-based with your diet?

Marcel van der Wouw, PhD (guest):

Yeah, great question. I guess the main reason is that it's just way better for the environment, but it's also from an ethical perspective. It just feels better to move towards a more vegetarian diet and vegetarian direction, and there's another one that kind of-

Dr. Travis Cox (host):

The health [inaudible 00:03:47].

Marcel van der Wouw, PhD (guest):

Health reason, yeah. That's also a huge component. So there's a myriad of reasons essentially.

Dr. Travis Cox (host):

Yeah. I find it interesting when I delve into the research on your vegan diets, et cetera, when I read up more on it, I almost become invigorated, like, oh, I'm glad I'm plant-based, but I kind of worry about other people that aren't more plant-based because of some of the research when I read it, how vastly healthful it is to be more plant-based for your cardiovascular risk factors and for cancers and metabolic syndromes like diabetes, et cetera. And that being said, take a segue into more about what we're going to talk about today and this episode, which is gut health and a plant-based diet. So you have a very large experience with gut microbiota and its connection to health outcomes. Can you just take our listeners through a brief overview of the basics of the gut microbiome?

Marcel van der Wouw, PhD (guest):

Yeah, of course. So I'll start with the microbiome, which are all the sort of microorganisms that live within our body as well as on our body. So here we're talking about bacteria, fungi, but also viruses. And what's always sort of staggering is that the amount of these microbes that are sort of around us and on us is almost the same number as the... or sometimes it slightly surpasses the amount of cells that we have in our body. So it's really is just a staggering amount.

Dr. Travis Cox (host):

Mm-hmm (affirmative).

Marcel van der Wouw, PhD (guest):

And this relationship between all these microbes and our sort of own health is really this sort of symbiotic working together relationship where we're both sort of trying to promote health, I think to some extent.

Dr. Travis Cox (host):

Mm-hmm (affirmative).

Marcel van der Wouw, PhD (guest):

The reason I think why we should care and care about these different microbes is because they have a huge influence on our healthy living from that perspective, and thinking specifically about diet as well, is all the food that we eat goes into our gastrointestinal tract. And a lot of these nutrients are sort of broken down and changed into the next metabolite or next nutrient that a body uses and uptakes. So for a lot of very specific nutrients, these microbes sort of form this bridge between diets and our health, which really emphasizes why it's so important that we care about these microbes.

Dr. Travis Cox (host):

Absolutely. No, I find that very interesting that we are almost more microorganism than we are human cells.

Marcel van der Wouw, PhD (guest):

Yeah.

Dr. Travis Cox (host):

But living in this symbiotic relationship could be a benefit, or it could be a detriment depending on the health status of that or those different microbiomes, which don't just exist in the gut.

It seems like with the literature, there is a lot more health benefits to eating more fibrous-rich plants for the gut microbiota. Can you just talk more about some specific literature on that topic?

Marcel van der Wouw, PhD (guest):

Yeah, of course. So there was a paper that actually came out about a month ago or so, and they compared long term individuals who were eating a long term vegan diet or a long term omnivore diet. In the vegan group they had 62 individuals, in the omnivore diet 33. And what they really tried to compare is how are their microbiomes differing, if that makes sense.

Dr. Travis Cox (host):

Mm-hmm (affirmative).

Marcel van der Wouw, PhD (guest):

So overall, what they found was that there were small differences in the types of bacteria that lived there. So those were at least within their study, more minimal, but when they looked at sort of the metabolites they produce, so once again thinking about this bridge of getting on the other side of that bridge, there were vast differences in specific types of metabolites, where for instance, one class of metabolite, called short chain fatty acids, were elevated in the vegan group essentially. And these short chain fatty acids are very health promoting from that perspective. So long story short, this paper sort of highlighted some of the positive microbiome-related effects of a vegan diet, essentially.

Dr. Travis Cox (host):

Mm-hmm (affirmative). Yeah, I found that paper very interesting, that the vegan diet associated with not so much increased diversity or increased sort of which type of those [phyla 00:08:23] or [genera 00:08:24] of microorganisms exist in the gut microbiota in these omnivores versus vegans, but more so what those microbes were doing to turn on or inactivate or activate these different nutrients for the health benefit of the host being the human. I found that really interesting because I was more familiar with other research articles explaining more of the differences in gut microbiota, even though it's not cut and dry and the same for everyone that's a vegan versus omnivore. But there is other evidence to support that there is a benefit for diversity, but it's not just about who's in the gut or variety of those microorganisms in the gut, but also what byproducts you are creating for the host, right?

Marcel van der Wouw, PhD (guest):

Yeah, exactly.

Dr. Travis Cox (host):

So can you explain some of these of metabolites? I believe you mentioned that was kind of the main takeaway from this paper. So what are some examples of those metabolites?

Marcel van der Wouw, PhD (guest):

Great, great question. So some metabolites are a bit well more known. So also my niche within sort of microbiome work is its relation to sort of the brain and how we feel in our mood. So my focus is then also on metabolites that are associated with the brain. And what I think is always very fascinating about the microbiome is that it does have the capacity to create specific neurotransmitters and compounds that are very neuroactive. So just an example of that, serotonin is highly created in the gut. If I'm correct even, a vast portion of the serotonin within our body is within the gastrointestinal tracts, keeping in mind that's a reservoir of serotonin, might not necessarily be related to the brain because there's quite a bit of space and equity between them. But I think it's very fascinating. And some other examples are, for instance, [GABA 00:10:18] or dopamine precursors are also created there.

There's also another class which are called short chain fatty acids and a lot of my work is focused on short chain fatty acids. And what's really cool about this specific set of compounds is that these are primarily created when we eat fibers. So some of these fibers, our own body can't necessarily break down, but when these fibers reach the more distal part of our gastrointestinal part, so the later parts, there are a lot of bacteria that break down these fibers into these short chain fatty acids. And these short chain fatty acids are then highly absorbed by our body, and then really promotes specific health aspects of our body. Thinking about gut health, thinking about immune system health, thinking about metabolic health and even more and more research seems to indicate that these short chain fatty acids have a good impacts on our brain as well, which I think is really exciting.

Dr. Travis Cox (host):

Mm-hmm (affirmative). Yeah, super exciting. That's awesome. And I think one of those kind of takeaways from that first paper you mentioned, is the impact of those short chain fatty acids in the vegans that seem to have a significant difference or improvement on glucose or blood sugar metabolism and lipid metabolism and made it so that they had a higher chance of having a good, healthy metabolism so they could decrease the chances of having, I mean, hopefully decrease the chance of having things diabetes or obesity and those kind of metabolic syndromes.

Do you know of any other research that you could speak of that shows the benefits of a vegan diet.

Marcel van der Wouw, PhD (guest):

 Yeah.

Dr. Travis Cox (host):

In creating more of a healthier metabolic system in the body?

Marcel van der Wouw, PhD (guest):

Yeah. That's a great question. So there's another paper that's more of an intervention study and the reason why intervention studies are, I think really exciting in this realm specifically also, is because the previous study we discussed is more of a cross sectional study. And we're not really sure if they're variables behind the scenes that might be drawing some of these effects. So one can imagine a person that has a vegan lifestyle might also be more physically active, goes to the gym a lot more, and there can be a whole difference in sort of characteristics there, that might also affect what we're looking at.

Dr. Travis Cox (host):

Right.

Marcel van der Wouw, PhD (guest):

But then if you start looking at an intervention study, which we're going to move into now, that's when you really can sort of tease apart these individual differences. And there was a study published about two years ago, that was one of the sort of intervention trials, where they had about 168 individuals that they split up between a vegan diet or a control diet in this case.

Dr. Travis Cox (host):

Mm-hmm (affirmative).

Marcel van der Wouw, PhD (guest):

And one of the interesting things as a result of this diet as well, was a reduction in sort of calorie intake, I think with a reduction of 500 calories on a daily basis, which I think is already amazing, honestly. And if you then look at sort of the positive effects on BMI and other sort of health variables, you also see a reduction in BMI and fat mass. And then once again, taking it back to the fiber and to the short chain fatty acids, we once again see that increase in fiber intake and that increase in short chain fatty acids. So even if we look at it from an intervention study, we see these quite consistent change then once again, that we discussed previously, which I think is super exciting.

Dr. Travis Cox (host):

No, definitely. Yeah. So from this study, it seems that the change from a normal omnivorous western diet to a, I believe it was a low fat vegan diet, and they did that for a period of time. And they noticed that there was increased short chain fatty acid production that influenced positively lipid metabolism and glucose blood sugar metabolism, so that it led for a decrease in the fat mass or the unhealthy body weight of these overweight individuals, which is amazing that your diet, not just from a caloric intake, but from a quality of what's in that diet that affects the gut microbiota, not just what is calories and calories out affects the health benefits, which is awesome. And I think I should have reviewed that paper because you shared it with me previously before our podcast here. But there was a particular finding I thought it was really cool was that there was a particular phylum of these microorganisms that is responsible approximately increasing caloric expenditure, burning more calories on their own accord, by over 150 kilo calories per day, which is interesting.

If you think about your microorganisms are burning calories for you without having to necessarily work out to burn those calories, then that's going to help you of course get to or retain a healthy body weight, which is really interesting.

Marcel van der Wouw, PhD (guest):

Yeah, definitely. And I think that also supports sort of this concept of having a long term healthy diet. It really sets up that positive ecosystem within your gastrointestinal tract for long term health as well then. And what's also then interesting is this long term ecosystem. Even if you have a day off where your diet is slightly off and perhaps you eat a little bit more junk food, it returns back to baseline pretty consistently if you have sort of this long term aspect as well. So I think that's one of the exciting parts of the microbiome as well, is this, you can set it up to really support your health altogether so...

Dr. Travis Cox (host):

Absolutely. So yeah, these effects are changes of the microbiota in the gut are not temporary. If you have it change over time or it's maintained over time through a healthier plant-based diet, then you're able to retain the benefits of that kind of, like you said, ecosystem within your gut. And if you have a bad day or like you said, eat some junk food, you're not going to totally lose and revert back to an unhealthy microbiota in your gut. What would be the... I mean, I think I might know the answer, but what would be the number one thing that might cause there to be a total disruption of the gut microbiota to cause it to go towards that [dysbiotic 00:16:50] unhealthy state?

Marcel van der Wouw, PhD (guest):

I mean, antibiotics, it's quite literally just a wipe out of all the entire [inaudible 00:16:58].

Dr. Travis Cox (host):

Right. Okay. [inaudible 00:17:01] bomb, I must say.

Marcel van der Wouw, PhD (guest):

Essentially, essentially. I do think that some of the research indicates that one or two weeks after antibiotics, your microbiome does go back to baseline and does try to go back to its normal self. So that's a positive thing, but yeah.

Dr. Travis Cox (host):

And would you say things, I mean, I don't know any specific research off hand, but I recall reviewing some of the past where chronic stress or of course, poor diet and even things like certain ingredients in processed foods like emulsifiers, et cetera, can actually disrupt the gut microbiota, which cause it to kind of go away from that healthier state. Do you know of anything off the top of your head with regards to stress that could do that? Because you work a lot with the brain and the gut?

Marcel van der Wouw, PhD (guest):

Yeah. Yeah. That's a really good question. So from people's experiences, you might recognize that the moment you're stressed, you might experience some changes in your gastrointestinal tract. You might have a bit of an upset tummy and quite often this is then also paired with changes in gastrointestinal motility. So how quickly stuff moves through a gastrointestinal tract and that this [inaudible 00:18:16] itself will change the microbiome as well. But there's also some really more [solo 00:18:23] mechanisms at play, I think where your body also talks back to the gut microbiome by secreting different compounds into the gastrointestinal tract, which is one of the ways in which it sort of remains stable and can recover after antibiotics. But I would imagine that chronic stress will also impact those subtle sort of ways of talking between our body and the microbiome.

Dr. Travis Cox (host):

Yeah. And is that something that would happen via hormones in the blood that goes to the gut or more from the vagus nerve coming from the brain down to the [enteric plexus 00:18:57] in the gut? How would you say that mostly or is it both?

Marcel van der Wouw, PhD (guest):

Probably both. I think at this stage within research, we're still trying to figure out the specific details of how this crosstalk works. Some research does seem to indicate that our body's able to secrete immune system related compounds into the gastrointestinal tract and that those can influence the composition of our gut microbiome. So I think there's some really exciting work that's being done there, but with the microbiome, there's so much still that we don't know and so much excitements about it that yeah, we still have ways to go essentially.

Dr. Travis Cox (host):

Well, absolutely. That's why you're doing your fellowship of their PhD at University of Calgary of course here. There's more to be researched, more to be real understood and of course hopefully applied in the clinical setting so we can get the takeaways of these relationships. So we can naturally help people get healthier or get back to health if they've lost it in regards to their gut and their whole body or body and gut.

Marcel van der Wouw, PhD (guest):

Yeah, exactly.

Dr. Travis Cox (host):

So curious to know more about the short chain fatty acids because that seems to be more of a paradigm shift, I mean, if I were to step back and let's say, ask my average patient about, hey, do you know anything about the gut microbiota? They say, oh yeah, you got to eat [inaudible 00:20:19] foods and probiotics and that helps your health. How? I don't know, but it seems not so much about the microorganism, the gut or who's there, or the diversity maybe as much as what they actually produce as far as the short chain fatty acids, another metabolite, so can you maybe dive a little deeper talking about the relationship of the short chain fatty acids and kind of different mechanisms in our health?

Marcel van der Wouw, PhD (guest):

Yeah, that's a great question. There's a lot to go here, so I'm going to try my best not to go on tangents, left, right and center.

Dr. Travis Cox (host):

Totally. Yep.

Marcel van der Wouw, PhD (guest):

So it all really starts within sort of the colon, I guess, which is where most of these short chain fatty acids are created. And I would like to also point out that there are three main types of short chain fatty acids that are produced by your gut microbiome. These are called acetates, propionates and butyrates. And these also have sort of slightly different characteristics, where some of them are a bit more easily absorbed or a bit more easily used for one thing rather than another.

Dr. Travis Cox (host):

Mm-hmm (affirmative).

Marcel van der Wouw, PhD (guest):

So we'll start with what happens in the [gut end 00:21:30] specifically. First of all, these short chain fatty acids are absorbed and pass our bloodstream and specifically butyrate then, while it is going through the wall of our intestines is used as a energy resource. So butyrate is really one of these compounds that really fosters gut health and healthy gut permeability as well. Some people might be familiar with the leaky gut syndrome where there's where the gut is more permeable than it is optimal.

And this can result in specific toxins, for instance, sort of seeping through the gastrointestinal tracts into the bloodstream and butyrates, really especially in the colon is able to foster this healthy gut intestinal wall or barrier.

Dr. Travis Cox (host):

Mm-hmm (affirmative).

Marcel van der Wouw, PhD (guest):

Then taking it a step further. There are also nerves that innovates the gastrointestinal tract tissue as well. And these nerves directly go into the brain as well. So short chain fatty acids can also activate this nerve called the vagus nerve, which is another way in which we expect the short chain fatty acids to signal. They're also gut hormones that are secreted by the gut, which can also be activated by these short chain fatty acids. And then the remaining short chain fatty acids can go into the liver, are metabolized by the liver to some extent, and then primarily as this is the one that actually makes them to the bloodstream and those additional functions within the body and that's it from a physiological perspective, those are sort of the major ways so it's a lot. A lot of research has been done and it's a lot. Yeah.

Dr. Travis Cox (host):

No, definitely. And that seems to be really interesting. The fact that these byproducts of these microbes in our gut microbiomes are the ones more helpful in promoting that healthy gut system. And of course communicating the brain like you mentioned, and creating this kind of homeostasis, this health balance effect. And when we just back up a little bit and take a look at those two first research articles that we briefly went over, they kind of indicated that plant-based diet that has higher fiber intake is going to influence our microbes ability to produce these byproducts, like short chain fatty acids that have the health benefit. Not so much as simple as you get more microbes in your gut or you have a more variety of better diversity and that's going to directly affect it. It's actually a little more subtle than that, or a little more in depth. And that's what I find the most interesting is the fact that these plant-based diets with high fiber can actually do that. And that's what we are aiming for in a plant-based dietary approach, right.

You mentioned before, again, the connection between the gut microbiota and the brain, and of course those byproducts or short chain fatty acids that can really directly influence the brain. Would you say that there's any particular direct benefit? Let's say if I'm just talking about layman's terms, for the brain, I think about mental health, depression or anxiety, or kind of worry or just bad mental states that are unpleasant, are you familiar with any of the evidence that supports that gut microbiomes influence on those kind of mood states?

Marcel van der Wouw, PhD (guest):

That's a great question. It's a difficult research question sometimes to investigate as well, because some of these short chain fatty acids as butyrate and propionate, they don't really reach the brain. So then we're talking about these sort of different cascading effects, which are difficult sometimes to untangle. But some of the research does seem to indicate there was a very, very interesting paper out in 2019, I think, where they looked at sort of the microbes and what are they able to do from a functional perspective. So they looked at types of microbes and can these type of microbes produce short chain fatty acids. And then what they further found is that there was a correlation between microbes that produced butyrates, those correlated with sort of depression and quality of life scores, in the sense that if you have more microbes that produce butyrates, these individual individuals also tend to have better mental health from those two metrics as well. And it was a huge study where they looked at like thousand different participants. And I think that study really bolstered my excitement as well, to really start going more into this direction. Yeah.

Dr. Travis Cox (host):

Mm-hmm (affirmative). Definitely. That's awesome. And for our listeners that are wondering all these research articles that we're referring to, I'll make sure that I confirm them with Marcel after the show here and put them in the description, the podcast notes, because yeah, I think we've done a lot of heavy lifting and unpacking the understandings of these... Yeah, like you said, the bridge between our diet and these health outcomes and that bridge is primarily that gut microbiota. And beyond that, there's actually more mechanisms at play. Like you say, there's a lot more of these cascades, these domino effects of different mechanisms in the body that go beyond that. And it gets pretty complicated, pretty fast. And that's why there's all this kind of push to get more research and more understandings of these mechanisms. And it doesn't start at a, hey, let's do a quick clinical trial intervention and see how making Marcel eat pure vegan diet for three years will help him improve his health.

It's obviously harder to do those more complex research studies and of course takes more funding, more time. So I think Marcel, what we will do, just for the sake of sanity for our listeners. I think that a lot of this information is more intense than my typical podcast episode. So what we'll do is we'll wrap up today and perhaps if you're willing, we'll record another episode another date where we can actually dive more into the kind of that psychological mental health or stress from the mind side connection with the gut microbiota and so the listeners that want to dive deeper can get that information in another episode. Does that sound like you could do that?

Marcel van der Wouw, PhD (guest):

That sounds wonderful. Thank you so much.

Dr. Travis Cox (host):

Awesome. Of course. And before we wrap up here for this episode, what would be your advice? I mean, understanding you're not a clinician and of course whoever's listening, knowing that this information is not going to replace any health information or health advice you get from your primary healthcare provider, but what would be your advice for anyone considering going onto a plant-based diet, wanting to get that positive health effect of a healthier microbiota and healthier body?

Marcel van der Wouw, PhD (guest):

Yeah, I would give two overall advices. One is make sure you have a varied diet, a varied diet will lead to more different types of microbes in your gut system. And this step typically has a very strong correlation to human health. So eat a variety of different foods and then to really bolster sort of fiber consumption, leafy greens can be a great source of dietary fibers. Yeah. Essentially vegetables to begin with, which is kind of nicely in the wheelhouse of a vegetarian and vegan diet as well so...