What Are the Hidden Costs of Modern Hygiene?
Chris Kresser: Sure. I can just give a brief topline summary. We’ve talked about this before in more detail when
we had Moises Velasquez-Manoff, author of An Epidemic of Absence, on the show to talk about the “old friends” or hygiene hypothesis, which is the idea that we co-evolved with certain microorganisms that turn out to play a crucial role in regulating our immune system, and the disappearance of those microorganisms over the last hundred years in the industrialized world has led to a dramatic increase in chronic inflammatory disorders that can basically be separated into three categories: autoimmune disease, allergies, and then just general inflammatory conditions like asthma and arthritis, eczema, psoriasis, etc.
There’s a lot of evidence to support this hypothesis. You can look at epidemiological studies which show that the incidence of these inflammatory conditions is basically a mirror image of geographical maps of the incidence of helminth infections. Helminths are worm-like parasites that are considered to be “old friends,” meaning we evolved over a very long period of time with them, and they plan an important role in regulating our immune system. And so if you look at maps of helminth infections, they’re basically a flip-flop of maps of chronic inflammatory diseases, and the same is true when you look at levels of exposure to things like saprophytic mycobacteria, which is a kind of bacteria that are present in soil and untreated water that we’ve been exposed to throughout our entire evolutionary history but is increasingly absent in the modern environment because of changes. Essentially there is what we might call, not just a Paleolithic approach to food, but there’s a Paleolithic microbiome, and that microbiome has profound impacts on our physiology and particularly our immune system, and the shift in that microbiome may actually even be more important in some ways in terms of its effect on our health than the shift from a hunter-gatherer lifestyle to agriculture.
You may remember, Steve, when I talked about this in my presentation, what’s really interesting is there’s the theory that’s prevalent in the paleo community that the shift from a hunter-gatherer lifestyle to agriculture led to an increase in inflammatory disease and worsening in health, and there’s no doubt that there’s evidence that moving from a hunter-gatherer lifestyle to agriculture did lead to a decline in certain measures of human health, but the idea that compounds like gluten and saponins and lectins and capsaicin in peppers were responsible for this decline isn’t very well supported by the evidence because the significant increases in chronic inflammatory disease didn’t happen, really, until the last hundred years, and the change from a hunter-gatherer lifestyle to agriculture happened a full 10,000 years ago at least, maybe more like 11,000 or 12,000 years ago in certain areas. So there has to be something else that explains this because if it was true that gluten and capsaicin and lectins significantly increase the risk of inflammatory disease, it would have done that a lot longer ago than it actually did. And when you look at the evidence, one of the things that might clarify this or tie this together is it’s possible that those compounds in Neolithic foods are not a significant risk factor for inflammatory disease as long as the Paleolithic microbiome is still intact, whereas if the Paleolithic microbiome has been depleted or altered by sanitation and hygiene and other aspects of the modern lifestyle, then those foods do become risk factors for inflammatory disease.
I think actually this is probably the most important part of my whole talk, and it was a little bit buried in there. I hope it came across clearly because, for me, this has been one of the big challenges of resolving some of the apparent conflicts in this ancestral paradigm, is that if you ever talk to someone who’s well informed about anthropology and the history of human health and you say to them that grains have significantly increased the risk of inflammatory disorders, they might turn around and say: Really? Well, how did that not happen when all of these cultures were eating grains for thousands of years and those disorders were incredibly rare? Weston A. Price, for example, studied the people in the Lötschental Valley in Switzerland and the Scottish and Gaelic living in the Outer Hebrides both of whom relied on grains and dairy as staples. And then there are contemporary agricultural communities in South America and other parts of the world that really rely on tomatoes and grains and other foods that contain these Neolithic compounds, and yet autoimmune disease and asthma and things like that are really rare in those places.
We have to be able to resolve that contradiction if we want people to take us seriously when we talk about this diet, and so this “old friends” hypothesis is a way of really tying that together. And the way I would explain it to people now is by saying, look, it’s possible that if we still had the Paleolithic microbiome intact, we could tolerate grains and all of these compounds with no problem. And perhaps that explains why some people are able to tolerate those foods with apparently no problems.
But given that the microbiome has changed so significantly because of things like sanitation and hygiene and also increased use of antibiotics and decline in the consumption of fermented foods and fermentable substrates that lead to a better gut microbiome, and increased use of soaps, which actually deplete the skin from certain types of ammonia-oxidizing bacteria that we’ve evolved with for a long time, a decline in breastfeeding – because of all of that, these foods which didn’t really bother us that much for many thousands of years when our microbiome was still intact are now significant risk factors for inflammatory disease, and that’s the reason why I tend to recommend that people avoid or minimize them because we’re not living with that microbiome still intact, and there are many other aspects of the modern lifestyle that are problematic and hostile to our immune system.
So given all of that, it makes sense to me to minimize the inputs that could potentially dysregulate the system in spite of the fact that it’s theoretically possible and even epidemiologically likely that those foods are not the sole cause of an increase in inflammatory disorders.
Steve Wright: So if I understand what you just said and if I understood the talk correctly, basically the prevalence of a different gut microbiome, which your talk specifically centered in on some specific parasites, but also talked about how there was typically probably a completely different makeup because we know that that changes based on what you eat and where you live and everything, but if we focus more on this other microbiome, then it basically modulated the immune system so it made us less reactive to potential problematic foods or other things in our environment, right?
Chris Kresser: Yep. That’s pretty much it. Let’s take helminths as an example. These are the worm-like parasites that we co-evolved with for millions of years, and in fact, helminth infections first started between 564 and 528 million years ago, so we’re talking about a very, very long time. There’s evidence that not only all humans, not only all hominids, not only all mammals, but all vertebrates in the history of evolution have been exposed to helminths and infected by helminths. And if that’s true, which it certainly seems to be, based on the fossil record, then there’s actually evidence suggesting that the adaptive immune system, which is one part of our immune system that evolved in response to helminth infection, which indicates that our immune system can’t really even function as it was designed to do without helminths being present, which is kind of a mind-blowing concept, right?! That are immune system is really not normal if helminths, which are parasites, are not present, and I think that’s a difficult concept to grasp. We’re conditioned to think that parasites are harmful, and of course, some are. Some are very harmful. This is not to suggest that we have this relationship with all parasites. But helminths have been around for a long time, and our immune system is tuned to expect their presence.
What they do is they have gently suppressed inflammatory responses, and that has acted as a type of brake, if we’re going to use an analogy. Our immune system has one foot on the brake throughout most of its history, and then there are these other genetic variants that were selected for that restored inflammatory responses when helminths were present. Why would this happen? Well, let’s say you live in an area where malaria is endemic, and inflammation is the body’s way of fighting malaria off, so if you had helminths that suppress your inflammatory response, that could potentially be a disadvantage in that situation, and any genetic variants that arose that restored inflammatory responses in that situation would have been selected for. Those genetic variants were like having one foot on the accelerator, so we had one accelerator and one foot on the brake, and it kept our immune system in a type of dynamic balance.
Then all of a sudden in the last hundred years or less – because in 1947 in Europe, for example, a third of the population or more than a third still had helminths; we’re talking about a relatively recent period of time – helminths completely disappeared from the environment and from our guts, and so that foot on the brake that was providing that dynamic tension with the accelerator, so to speak, was gone, and the pedal was to the metal [indiscernible] this really dramatic epidemic of inflammatory disease because there’s nothing now that’s preventing excess inflammation that’s caused by those genetic variants.
Steve Wright: This wasn’t part of your talk, but I think it’s a question on my mind and probably others who watched your talk: How do we start to reconcile the fact that only some of us – well, it is a big enough portion of the population – are having allergies, asthma, inflammatory disorders, but nowhere near the majority yet are having those? Are do we begin to reconcile that? We know that everything has changed. The food has changed, the environment has changed, and the microbiome has changed, and there are only some of us who are extremely affected by this.
Chris Kresser: Well, actually 1 in 2 people now has allergies in the industrialized world, so that is nearly a majority, and it’s shocking when you really contemplate it. It’s 1 in 10 for autoimmune disease, and it’s tens of millions for chronic inflammatory conditions. The numbers are pretty impressive when you think about it, but nevertheless, the answer to that question, I already alluded to it. It’s a combination of genetic susceptibility, so I just talked about these genetic variants that evolved in places where other acute infections were endemic, like malaria, and they evolved as a way of protecting us from those life-threatening infections, especially when helminths were present because helminths kind of suppressed the immune response or the inflammatory response, and that’s beneficial in a certain way in that it protects us from autoimmune disease and allergies and inflammatory conditions, but it’s potentially harmful when we can get an infection like malaria and die unless we’re able to mount a sufficient inflammatory response.
There were certain areas where those genetic variants were selected for and more common. An example of this is Sardinia. Right now in Sardinia, 1 in 430 people has multiple sclerosis, and 1 in 270 has type 1 diabetes, which are extraordinarily high rates when you consider the global averages. So why are rates so high there? Well, malaria was very common in Sardinia up until it was eradicated from the island in the 1950s, and so all the people who live on Sardinia had these genes that promoted inflammation in order to help them fight off malaria infection, and as long as malaria was present at the same time, those genes didn’t lead to excess inflammation because the malaria was keeping it in check. But then when malaria was eradicated from the island in the 1950s, everyone still had those genes that promote excess inflammation, but the malaria was no longer keeping it in check, so those genes, all of a sudden, became a risk factor for autoimmune disease.
So definitely genetic predisposition is playing a big role here. Some people have these genetic variants that promote inflammation, and if they had helminths, those genetic variants wouldn’t be an issue and they wouldn’t be subject to an increased risk of autoimmune disease. And not just helminths, also the saprophytic mycobacteria and early exposure maybe even to certain viruses, like hepatitis A, and certain bacteria, like H. pylori, which is harmful later in life but may even be protective earlier in life. There are all these different aspects of the microbiome that help suppress inflammatory responses and protect against any excessive inflammation that would have been caused by these genetic variants. So that’s number one. And then number two is just exposure to other aspects of the modern lifestyle that predispose us to autoimmune disease and inflammatory conditions.
For example, if you’ve taken a lot of antibiotics when you were a kid, that had a significant impact on the microbiome, which, again, as I mentioned, shifts our susceptibility to inflammatory disease. It makes it more likely that you’ll have a leaky gut, which Dr. Fasano, who we’ve had on the show in the past, suggests is a big risk factor for autoimmune disease and may even be a precondition, which means that you can’t even develop autoimmune disease without having a leaky gut. And there’s exposure to environmental toxins. There’s exposure to food toxins. The poor-quality Western diet certainly affects the microbiome.
Basically what determines whether someone will manifest autoimmune or allergies or inflammatory disease is a combination of genetics, the status of their microbiome, and then the presence of environmental triggers, like poor diet, stress, sleep deprivation, and environmental toxins, to name a few.
Other ways to control inflammation
Steve Wright: OK, awesome. So that kind of leaves us with the question, and you’ve spoken about this before, that as you just said, H. pylori early in life seems to show a lot of benefit but late in life can be potentially carcinogenic, and you’re saying some people respond to helminth therapy and others don’t. I don’t hear you advocating for everybody getting helminths, so what are some other ways that people can take action and maybe do things to help downregulate their inflammatory response?
Chris Kresser: Well, let me just clarify something: I think the evidence is fairly clear that early exposure to helminths while the immune system is still developing is protective, meaning people who have helminths early on in life have a lower risk of developing inflammatory disease. What’s less clear is whether inoculating yourself with helminths after inflammatory disease has already manifested or after the immune system is fully developed has the same protective effect. There’s some evidence that it can be therapeutic and even reverse some of these conditions, but as you pointed out, as I mentioned in my talk, not all evidence supports that. There have been some disappointing results.
So really, I do think actually that if we’re exposed to helminths early on in life, we have less of a risk of developing autoimmune and inflammatory disease. The question is for those of us who are adults is, does inoculating ourselves with hookworm, which is not easy or possibly even legal – There’s some gray area in terms of legality here. I mean, certainly there’s no law against somebody developing a parasite infection unintentionally or even intentionally if they want to do that to themselves, but the gray area is around people who offer that as a service and when money is changing hands and things like that. It’s being done, certainly, in the scientific community to study it, but the commercial application is a little fuzzy, shall we say?
But certainly there are other things that can be done that have already been accepted in the mainstream to help improve the microbiome, and that includes things like eating fermented foods. Fermented foods contain these kinds of bacteria that we’ve been exposed to for most of our history, and we’ve likely been eating fermented foods for a very long time because we didn’t have refrigerators until very recently, and fermentation was really one of the few ways that we could preserve food, so it’s been a part of our path.
And then there’s the idea of eating prebiotic foods or foods with a prebiotic effect, and these prebiotics essentially stimulate the growth of bacteria that are already present in our gut. Studies have shown that prebiotics actually have a more quantitative impact on the gut microbiota over time, which means that they increase the levels of healthy bacteria in the gut more than taking probiotics does. Taking probiotics tends to have more of a qualitative impact, meaning it cause dendritic cells to become anti-inflammatory, it drives the development of T regulatory cells, so essentially it helps regulate the immune system, but contrary to previous belief, studies have shown that probiotics don’t really have a significant quantitative impact over times. In other words, they don’t really “top up” depleted bacteria in the gut in the same way that prebiotics do.
There are three options for prebiotics. One is soluble fiber that has a prebiotic effect, and that’s found in certain vegetables like onions and Jerusalem artichokes and starchy tubers, other fruits and vegetables. And then resistant starch, which is harder to come by in the diet but is found in potatoes that have been cooked and cooled for around 24 hours, green bananas, green plantains, which are virtually impossible to eat raw unless you dehydrate them, which is one way to do it. You can put them in the dehydrator and make dehydrated green plantain chips. Or you can use potato starch. Richard Nikoley has written a series on resistant starch on his blog, Free the Animal, so you might want to check that out if you’re interested. He did some experimentation with it himself and had a guest blogger who has done a lot of research on it come in and talk about it, too. So those are the ways you can do it with diet. I mean, it essentially involves eating a lot of fermentable fibers, if we were going to summarize it.
Then there are supplements that you can take that are commercial prebiotics that contain things like inulin and galactooligosaccharides. Now, the caution here is that many foods with prebiotic effect, with the exception of starch, are FODMAPs, and those can be problematic in people who have gut issues like IBS or IBD, especially if they’re eaten indiscriminately. What I’ve found, which is interesting, is that even in people who are FODMAP sensitive, if their flora is really disrupted, taking a commercial prebiotic at a very low dose to start with and then maybe increasing very slowly over time can still be beneficial is though that seems somewhat contradictory because they’re really trying to avoid FODMAPs in food for the most part. Taking a little bit of things like inulin and galactooligosaccharides, if they start at a low enough dose and build up slowly, can significantly increase the gut flora, which then paradoxically can make them less sensitive to FODMAPs over time.
That’s what I’ve noticed in working with patients, and I’ve also seen that prebiotics, in general, tend to be more helpful for constipation than probiotics, with the exception of some probiotics, like Prescript-Assist and maybe Mutaflor.
Steve Wright: Awesome. Yeah, I’ve actually seen the same thing with constipation and based on your work with other people on our blog and clients that we have.
Chris Kresser: Mm-hmm.
Steve Wright: So I also have come to similar conclusions working with people that the FODMAP diet seems to work really well to alleviate symptoms, yet paradoxically, as people heal, they almost need to reverse their thoughts on the FODMAPs and begin to eat those foods again.
Chris Kresser: Sure. I mean, if they can or even just, like I said, using maybe some resistant starch, like potato starch, or some commercial prebiotics in a therapeutic way because sometimes it’s a little easier to control your dose of things like that than it is to control the exposure to prebiotic ingredients in food.
Steve Wright: Right. That’s makes sense.
Chris Kresser: Yeah.
Steve Wright: So what are you thinking about doing with Sylvie?
