Small, deliberate stressors can strengthen the body when recovery is built into the ritual. In this conversation from the source, the useful thread is not novelty. It is agency: what the body can learn when the signal is clear and the dose is respected.
Rhonda, welcome. This been a long time coming. Even longer than you know, because even before we discussed you coming on this podcast as a guest, I've been watching your content for a very long time. So, want to start off by saying thank you. You were the spearhead to break through from academic science to public education. So, I consider you first in and the rest of us are just in your wake. So, thank you for that. It's been Oh, that is so kind. Thank you so much. Well, it's absolutely true. I'm so excited to be here having a conversation with you. So, Well, it's absolutely true. If anyone does the research, they will realize that the statement I just made is absolutely true and there isn't even a close second, you know, any other public-facing educators that have formal science training and uh do regular posting of content um came in several years after you initiated it. So, we're all grateful. Uh I have so many questions, but I want to start off with a kind of a new but old theme that you're very familiar with. So, temperature is a powerful stimulus, as we know for biology, and you've covered a lot of material related to the utility of cold, but also the utility of heat. And as I learn more and more from your content and from the various papers, it seems that there's a bit of a a conundrum in that cold can stimulate a number of things like increases in metabolism, brown fat, etc. Hopefully, you'll tell us more about those. But, heat seems to be able to do a lot of the same things. And I wonder whether or not the discomfort of cold, deliberate cold exposure, and the discomfort of heat might be anchoring to the same pathway. So, would you mind sharing with us a little bit about what happens when we get into a cold environment on purpose and what happens when we get into a hot environment on purpose. And I'm hoping that this might eventually lead us to some point of convergent understanding. So, if you
convergent understanding. So, if you would. I would love to. Let's take a step back, and I think you brought up a really important point here, and I think that point has to do with the intermittent challenging of yourself, and and whether that is through, you know, temperature changes like cold or heat, or through other types of stressors like physical activity, or perhaps even dietary compounds that are found in plants. These are things like polyphenols or flavonols. Humans were, you know, we evolved to intermittently challenge ourselves. And before we had Instacart, where you could basically just get your food delivered to you, before the Industrial Revolution, you know, occurred, we were out hunting, and I say we, not us, but humans. We were out, you know, gathering. We were moving, um, and we had to be physically fit. You couldn't, you know, catch your prey if you were a sedentary slob, right? You were moving, and you had to like, you know, pick your berries. You had to move. And so, physical activity was a part of everyday life. And caloric restriction or intermittent fasting was also a part of it. This is another type of challenge, you know, we we didn't always, you know, have a prey that we caught, or maybe temperatures were such that, you know, there was nothing for us to gather, right? So, food scarcity was something common, as well as eating plants. So, getting these compounds that I mentioned. So, this is This These are all types of stress, intermittent challenges that activate genetic pathways in our bodies. These are often referred to in science as stress response pathways, because they respond to a little bit of stress, you know, physical activity is strenuous. Fasting is a little bit stressful. Heat, cold, these things are all types of little intermittent challenges. And, um, there is a a of cross-talk between these stressors and the genetic pathways that they activate. And these genetic pathways that are activated help you deal with stress. And they
you deal with stress. And they do it in a way that is not only beneficial to help you deal with that little stressor, exercise or heat, it's it stays active and it helps you deal with the stress of normal metabolism, normal immune function happening, just life, aging, right? So, this concept is referred to as hormesis, right? This is a uh a a little bit of stressful challenge that activates these stress response pathways in a beneficial way that is a net positive that actually, you know, is has a very profound antioxidant, anti-inflammatory response or, you know, or whatever the response is. It could be the production of more stem cells. These are cells that help regenerate different um cells within tissues or something like autophagy, which is a process that can clear away all the gunk inside of our cells, pieces of DNA, protein aggregates. So, you'll find that these stress response pathways are activated like by a a variety of stressors. So, for example, one pathway is called heat shock proteins. And as their name would apply, one would go, "Oh, they're activated by heat." Well, correct. They are activated very robustly by heat, and we can talk about that, but you know, you can eat a a plant like broccoli sprouts, which is high in something called sulforaphane. This is a a compound that um is is sort of like a hormetic compound or as David Sinclair likes to say, it's a xenohormetic compound. I love that term. Um and it activates heat shock proteins, among other things. It also act activates a very powerful detoxification pathway called NRF2, which helps you detoxify things like carcinogens that you're exposed to. Well, guess what? Heat activates that. So, what I'm getting at is there is overlap. Like, cold also activates heat shock proteins. You're like, "Really? Cold?" Yes, it activates These are stress response pathways, and they are activated by various types of stressors. Now, you know, you're going to more robustly activate heat shock proteins from heat versus cold, but there is some overlap. Um so, I think that sort of forms the foundation there.
that sort of forms the foundation there. Yeah, that's very helpful. And you know, it brings to mind in the context of the nervous system, I will tell people, you know, you only have a small kit of neurochemicals to work with. There isn't dopamine for um Netflix and then dopamine for relationship and dopamine for work, etc. They're dopamine is a generic pathway by which motivation, craving, and pursuit emerge. Etc. And just like adrenaline is a a generic theme of many different behaviors. And I It seems that it is the job of biological systems to be able to take a diverse range of inputs, even unknown inputs. Like, we don't know what technology will look like in 3 years, but you can bet that some of those novel technologies will tap into the very systems that I'm talking about now. And um there certainly will be other stressors to come about that will tap into these pathways. I have two questions related to what you just said uh before we talk a little bit more about cold and heat. It You mentioned plants as a a route to to creating intermittent challenge. There's a lot of debate, mostly online, about whether or not plants are our friends or plants are trying to kill us. Um the extreme version from the carnivore types um pure carnivore diet types is that plants are trying to kill us. From the plant-based diet folks, it seems like it's more about uh what's healthy for the planet, animals, and maybe for us. But, if we set aside that argument, and we just raise the hypothesis that plants have compounds that are bad for us, but maybe by consuming them in small amounts, they're creating this hormesis type scenario. So, then I think we conceivably solve the problem. We could say, "Yes, um plants are bad for us, but in small amounts they provide this hormetic response and they're good for us, right? So it in the same way that heat is too much heat is bad for us, too much cold is bad for us, can kill neurons, but appropriately dosed in an intermittent challenge type of scenarios can be good for us. Is that how I should think about plants and these compounds? Do you think of them as good for us or
Do you think of them as good for us or as um bad for us? They're a very sharp blade and we want to use them potently. I I actually I think that it's impo - almost impossible I mean you'd have to eat nothing but the same plant all day every day in large I mean the bioavailability of these these compounds in the plants they're attached to a food matrix. Um you know, it's it's not like taking it in a supplement form as well. Um it it's it's such that like it's it's very difficult to make it toxic. Now, there are some cases for example if you eat cabbage and I think there's some group in Africa or somewhere that like that's all they eat is cabbage and there's a goitrogen in cabbage. It's not sulforaphane, it's another compound, but that's all they eat every day. Nothing but that. And they get Yeah, and they're like iodine deficient on top of that. So um you know, I do think there's there you can of course make I mean there are types of plants that are toxic in small quantities, right? I mean Hemlock, exactly. So Folks don't don't play this game with hemlock. But you're not going to get poisoned from eating you know, your serving of broccoli at dinner, right? So I mean it it depends on the plant. It's it's I don't these generalizations are kind of they're just not useful and I think that a lot of people online um in the blogosphere it they gravitate towards them because it's just easier and it's a lot more sensational. I eat plants, meat and starches. I'm one of those rare omnivores out there now. I feel like I'm a rare it's rare to be an omnivore, but I think once you step out of the social media's as you said the blogosphere the most people I would say 99% of people on the planet are probably omnivores. Right. And someone will probably correct me, but I doubt the number falls below 90 98. I think if you look at data, you know, um and and when we have carnivore data I like I can't wait to see it, but like right now it's a lot of okay, well this is a lot of anecdotal
okay, well this is a lot of anecdotal evidence and there's you know, there's a good there's a lot of uh good starts with anecdotes, but like people change a thousand things at once and they don't realize that, but they do. And so anecdotal data is only so good, right? It's it's a starting point. Um and so we don't really know long-term what carnivore diets are going to do, you know, they may be beneficial short-term, um they may you know, be beneficial for reasons of elimination of other things like who knows, right? Lots of possibilities, but I do think with respect to plants um you know, that there's that that there's so much evidence like for example, sulforaphane is one that I I really like because um uh there's just evidence that sulforaphane is a very powerful activator of the NRF2 pathway. And this is a pathway that regulates a lot of genes and a lot of genes that are related to like glutathione production. Um genes that are involved in detoxifying compounds that we're exposed to from our food like heterocyclic amines. In fact, there have been GWA studies. So these are genetically um these are studies that are um genome-wide associated studies for people listening uh that aren't familiar. People have a variety of versions of genes and um we have a gene that's able to make um heterocyclic amines to basically detoxify it so it's not as harmful. Um and and people that don't have a certain version of that that's doing it well are very prone to like colon cancer and increased cancer risk, but if they eat a lot of broccoli and cruciferous vegetables it negates that risk because they're getting sulforaphane which activates a lot of the glutathione transferase and synthase genes. So glutathione's a major antioxidant in our brain and in in our vascular system in our body basically. So um you know, there's there's evidence that it that that eating things like you know compounds that are like sulforaphane or broccoli broccoli sprouts which have like a 100 up to 100 times
which have like a 100 up to 100 times more sulforaphane than broccoli are activating glutathione in the brain. There's human evidence of that. I mean that's amazing. That is amazing. And in plasma, yeah. Uh sorry to interrupt, but I just want to make sure when uh So broccoli sprouts are different than broccoli. Um and you just told us that they have much they're much richer in these um these compounds. So note to self I should have broccoli sprouts not just broccoli. Uh can we cook the broccoli and still get these nutrients or do we have to eat raw? I confess eating raw broccoli is really aversive to me. Um so the the sulforaphane is formed from a compound called glucoraphanin which is in the broccoli. And the enzyme that converts it into sulforaphane is myrosinase and it's heat sensitive. Uh so you do somewhat lower the sulforaphane levels when you cook the broccoli. However, um there was a study a few years back that showed adding 1 g of mustard seed powder ground mustard seed powder which also contains the myrosinase enzyme to your cooked broccoli increases the sulforaphane by fourfold. So mu - So Th - this is great cuz I confess I like broccoli if it's cooked to the appropriate density um not too mushy but definitely not raw. The idea of eating raw broccoli to me just sounds horrible but I I like the way mustard seed sounds. So just a little bit of mustard seed powder added to the cooked broccoli can recover some of these compounds. Yes. So what I do is I will, you know, lightly steam my broccoli and then I add a little bit of my Kerrygold butter um and then I add some mustard seed powder on the top of that. And it's got a little little kick, like it's just a little spice, you know, and if you don't taste that, it's expired. Like it should have a little kick. And because I know people will want to know how often and how much, um you know, are you eating this every day or most days of the week? Well, I had shifted to supplementation with sulforaphane. I I admitted I'm admitting right now that I've been terrible about it the past like
terrible about it the past like I don't know, 6 months or so. The supplementation or the broccoli? the supplementation. And um and uh so there's another way to get there's another compound and it's actually called moringa. And Dr. Jed Fahey, who's really the expert on sulforaphane, uh he's a good friend of mine. He's been on the podcast a couple of times. He um he he basically thinks and you know, has done a lot of research on moringa as well, that it's a it's like a cousin and it activates the NRF2 pathway similarly to sulforaphane. And so I've been buying this Kuli Kuli moringa powder. I don't have any affiliation with them, but Kuli Kuli is a brand. Kuli Kuli is the brand. So Whole Foods. I have no affiliation. But Jed Fahey like has researched it like like that specific brand and so it's like legit it's legit, you know, it's like science-backed um in terms of actually containing moringa and it activating NRF2. Um and I add it to my smoothies. So that's what I've been doing. What what are some um dose ranges? And of course we give the usual recommendations that people should talk to their physician, etc., but um if people are going to what do you take? That's always the let's take the the David Sinclairian approach. What do you where he'll talk about what he does um as a way to to deal with this and of course everybody's different and should uh in all seriousness should um anytime you add or delete something from your uh consumption should consult some trusted healthcare professional trusted by you. What do you recall the the dosages? a big heaping tablespoon. Um So Moringa Moringa sounds like a song. It's with a K. I know it is. Um but you know, for people also listening it's like why would I do that? You know, I mentioned the glutathione in the brain. I I mentioned it in um plasma. It's it's been shown to lower DNA damage in people and in in white blood cells. Uh it's also been shown and there's been several different studies in China. You know, in China there's a lot of air pollution and I mentioned that it you know, it's a very powerful
that it you know, it's a very powerful activator of Nrf2 and I know you're you're familiar with Nrf2 but Nrf2 is like it's a transcription factor that is it is binding to a little specific sequence in a variety of different genes and it's like turning them on. Uh or in some cases turning them off. It's regulating what's being activated or what's not being activated being turned off. And um some of the genes are are basically these these detoxifying pathways. We talked a little bit about the glutathione but there's also ones that are involved in um air airborne carcinogens like benzene. So benzene's found in air pollution. I mean cigarette smoke. If you're smoking cigarettes still like please try to quit. mutating your DNA. yeah, it's Like just saying nothing of the lung cancer, you're mutating your DNA. And heart disease risk but anyways, um people and this has been repeated in in more than one study that literally after 24 hours of taking can't remember off the top of my head what the dose of sulforaphane from broccoli extract broccoli um seed extract was or broccoli uh sprouts extract not the seed. It was the sprouts. Um anyways, they started excreting like 60% benzene and acrolein. I mean that's something that we get in cooked food. out in their urine. Coming out in their urine. Yeah. Well, I'm not a smoker and I have to be honest it's rare that I I of a supplement for the first time because I've been you know, deep diving on supplements since I was in my teens. This is fascinating and it brings me back to this question that we had before and I I appreciate that you've answered it very clearly. Plants have compounds that are good for us. They're not just stressing us. They're activating pathways that are reparative. That's what I'm taking away from what everything you're telling me. Right. And that our bodies were supposed to be getting that stress to have those pathways activated. Like it is like you know, right? I mean this is conserved among different animals. Like this is something that is it's supposed to happen. And in our modern-day world, we don't have to eat
modern-day world, we don't have to eat plants. We don't have to move anywhere or exercise. We don't have to go through periods of not eating food because we can have it at our fingertips at any second, right? So, I mean we've got this conundrum of we're never activating these stress response pathways that we're supposed to activate. We're supposed to. I find that fascinating and again drawing a parallel to the nervous system. So, what I'm hearing you say is that historically we would have to go through some stress, some confront cold or confront heat or confront effort or or hunger and have to exercise essentially in order to obtain these compounds and then those compounds are reparative. Yeah, I I feel that resembles uh the dopamine pathway. I always say, you know, there's nothing wrong with dopamine. People think about dopamine hits as bad or dopamine is bad. There's absolutely nothing wrong with dopamine. The problem is dopamine, especially high levels of dopamine released without the need for effort to access that dopamine is problematic. So, a line of cocaine gives you a ton of dopamine with no effort except to ingest the drug. Whereas um working for 4 years or more to get your degree will release a lot of dopamine and a lot of cortisol along the way as we know. And it's considered a healthy accomplishment in most cases. A tremendous amount of you we're approaching the spring and there'll be a lot of graduations. Weddings are coming up now that the pandemic is kind of hopefully slowing. And there'll be a lot of dopamine. High levels of dopamine are great, but only after the effort of having done something in order to access it. And so that's what I'm taking away from what you're saying is that we need to go through this intermittent the different types of intermittent challenge and we can we are rewarded with particular compounds that are reparative both for the challenge, but then it make us stronger. It is hormesis really is it seems a case of what doesn't kill us makes us stronger. Um What So you mentioned Can I add to that one thing you just said because because this has been shown with for example sulforaphane in animal studies you precondition give the animal
studies you precondition give the animal sulforaphane and then you expose them to like, you know, hypoxia or some kind of ischemic stroke condition, whatever they do to induce that. And the sulforaphane it basically protects that like it they're preconditioned and their stress response pathways are primed. And so when they're then exposed to the ischemic stroke, they their outcomes are so much better. So much better than the animals that didn't get the sulforaphane 48 hours before or whatever it was. You know, and and this is like this has been shown in multiple animal studies with sulforaphane specifically in the brain. Um I know Mark Mattson, uh Dr. Mark Mattson, he's a lot often thought of as the intermittent fasting king, but you know he's a neuro neuro scientist and he um he did publish some work and and talks about sulforaphane as well. I'm really glad you brought that up that example up because many of the questions I get on social media and elsewhere are about traumatic brain injury and TBI and you know, is just one example. Um and people always think oh sports, it's football. Whenever you say TBI people always think football. And I just wanted just take a a moment to editorialize. 90% or more of traumatic brain injury is construction work, at-home accidents. But, football players are a hockey players are a martial artists are a tiny fraction of the people who have TBI and concussion of various kinds. It just so happens that within those communities many of them, 75% or more, experience those. So, it's salient within those communities, but uh concussion is is prominent. People are always asking, "What can I do in order to offset brain injury? Uh I had a concussion 2 years ago. What can I do?" And and it's been a tough question because we really don't have anything for them. I mean, you tell them sleep well, eat well, exercise, but it sounds like some of these reparative pathways um either should be explored in the context of brain injury or I'm guessing are being explored in the context of brain injury. Yeah, so a couple of things there. Um one is that I mean, traumatic brain injury, I mean, it's terrible, but it's
injury, I mean, it's terrible, but it's also it's so interesting because it's also like literal real-time brain aging. Like, you know, like it's you're able to like accelerate it and understand. So, I I often think of when I think of traumatic brain injury, I think of so much overlap between Alzheimer's disease and dementia and these neurodegenerative diseases because there is a there are a lot of similarities that there, you know? And so so for our fan, I personally think um and I do think there's been some animal research with TBI. I mean, and and um so for our fan, mostly preconditioning rather than uh treatment. Um so again, it's like, well, I mean, if you're going to if you want a healthy lifestyle thing and you're a construction worker or you're fill in the blank that's, you know, going to I mean, anyone that drives in a car, I mean, you're at risk to some degree, right? Or bicycle. yeah. Around Stanford, we have, you know, I would say uh people demonize motorcycles, people demonize a lot of things, but moving fast through space on a small object next to a 3, 000-lb vehicle, I I we've lost We have a number of friends who've died. We have a number of people with traumatic brain injury. Um I'm not against cycling or cyclists, but it it is um it's a risky sport uh by any stretch. Um so, in taking things like Moringa or eating my broccoli sprouts, maybe cooking them a little less than I'm currently cooking them, putting on the the mustard seed. Uh is there evidence that Well, first of all, NRF2 is expressed in neurons, right? So, those those cells should be protected. Are there other cells of the body that could possibly gain protection from these pathways? Um well, lungs for one. Uh but, you know, just even in plasma cells I I mean, I think it's pretty NRF2 is pretty ubiquitously expressed. Liver. Uh so, there's I mean, there's there's so many animal studies that have looked at all those things. I try to kind of gravitate towards human ones cuz it's a little little a lot more relevant. Um but but I think, you know, overall, like I said I mentioned, you know, DNA damage lower I think it was like 24 24 or 34% lower in
think it was like 24 24 or 34% lower in um human blood cells after broccoli um broccoli sprout powder supplementation. Wow. Um and I made a video on this like years ago, in 2016 maybe, and I think I have like the references on there to exact amounts. I can't remember. the video, yeah. But it it was it's kind of an old video. It's to the 2016. But um I also had Jet on the podcast and he he did talk about this. Um but you know, it's also been shown in randomized controlled trials to help treat autism and autistic symptoms. And yet again, it's doing interesting things in the brain. And um I think if I think it does have something to do with the oxidative stress and the glutathione, which would be relevant for TBI treatment. Uh it hasn't been shown empirically that that helps with treatment, but I do think uh someone could do that study. Um I think that it it should be done, honestly, because it's a low-hanging fruit. I mean, if there's any impact, and there is at least one preliminary study that glutathione is increased in the brain after humans are, you know, basically taking sulforaphane. So, uh
Transcript auto-generated by YouTube. Verbatim — duplicates intentionally preserved.
Hormesis describes a simple biological pattern: a controlled challenge can make the body more resilient. Exercise does this. Heat does this. Cold and fasting can do this. The point is not the stress itself. The point is the adaptation that follows.
Cold exposure quickly changes breathing, circulation, and alertness. The nervous system receives a clear message and has to organize around it. Over time, the practice can teach steadiness under pressure.
sauna and other heat practices raise cardiovascular demand while the body stays still. Heat shock proteins help protect cellular function under stress. The felt experience is often quiet: deeper relaxation, easier sleep, and a sense of reset.
A hormetic practice without recovery becomes strain. The elegant protocol is measured. It asks enough of the body to build capacity, then gives it the conditions to repair.
The body adapts best when the challenge is deliberate and the return to calm is protected.
Start with one hormetic tool and make the dose easy to repeat.
Pair every stressor with recovery: hydration, food, sleep, and downshift time.
Use your next-day state as feedback, not just the intensity of the session.
