 Unlike Lisa Emerson's talk, which was funny, mine's gonna be pretty dry. I'm gonna blame it on the dehydrating effects of salt. Salt is such a huge topic, and I really only could talk about a tiny fraction of the things that one could imagine talking about with salt. And in fact, the one thing that I promised to talk about here, how much salt do we really need, was really kind of an over promise, and I'm very sorry, I can't possibly tell you that. But what I will talk about is ways that I see that different dietary contexts can affect your salt needs, and then you can maybe apply that to your own individual situation. So the reason that I became interested in this topic at all is because this growing difference that I was noticing between the ketogenic diet culture and the carnivore diet culture. So old school carnivore dieters like myself mostly actually avoid adding salt to our diets. We eat animal foods, few of any plants, and for most of us we don't even add any salt to our food, which is different from maybe more recent versions of the carnivore diet you might have heard, which say meat, salt, and water, that's not the old school. On the ketogenic diet, on the other hand, a lot of people are recommending eating very high amounts of salt, and lots of people swear by it and actually feel better, and so I have no dispute with that, but it made me very curious about whether some of these differences that we're seeing had some dietary origins, and that's what I wanna explore. So I'm gonna first briefly talk about this progression of claims that we've been seeing about salt that's really tied to the Western diet and doesn't necessarily have anything to do with any of our concerns here, and then claims that are more relevant to the sort of paleo ethos and talk about salt intake in humans across time and space, and then talk more about what claims are being made in the ketogenic diet space and how a ketogenic diet might affect salt needs and then go on to the carnivore diet and how plant eating might affect salt needs. So salt intake and the safety and healthfulness of it is controversial even in the conventional mainstream medical world, and has been for a really long time, but the focus of the controversy has been between whether it's detrimental or whether it's just neutral, and so it's quite interesting for the ketogenic diet community in particular to be now arguing that it's in fact beneficial or even necessary to eat high amounts of salt. So we've kind of opened the spectrum of what we're talking about, and it shifts the burden of proof somewhat, and it kind of opens the Overton window of what's possible to even consider. So we have this kind of hypnotizing pendulum going on from somehow in recognizing the error of the position on the left that you must decrease your salt intake. We've now zoomed past the middle and are arguing for the right, and I'm going to try to argue that the right is also wrong. So the left side of the pendulum has mostly been about blood pressure, salt's effect on blood pressure. I'm actually not going to go very deep on there because a lot of people have already written about it in depth, but just as an overview of what's at stake, high blood pressure is one of the main defining features of metabolic syndrome, so we know that blood pressure is something undesirable, and we do know that lowering salt can slightly lower your blood pressure and maybe more if your particular salt sensitive, but salt doesn't cause metabolic syndrome and if you lower salt, it doesn't solve your metabolic syndrome. If you want to solve metabolic syndrome, you need to do something different. So one of the people who wrote about this was Adele Hite, whom we lost this year, and I just want to take a moment to honor her memory. She made this really funny Facebook post in 2015. Hello, it's meat, and she had a really great sense of humor and a piercing sardonic wit and an exceptional capacity for nuance, and she'll be very missed. I like to imagine she could be saying hello from the other side. So as part of her investigations into the nutritional guidelines, she wrote a couple of posts on the topic of nutritional guidelines aimed at reducing salt intake, and one of her criticisms is about the methodology, which I agree with her quite a bit. Once a food item becomes a target of this kind of policy, the evidence after that point seems to not really matter how much sense it makes as long as it's consistent with the recommendation that's already in place. So once you've decided that salt being related to blood pressure is somehow actually causal of metabolic syndrome, and you put that idea into policy, then the gymnastics start. So we have this beautiful example here that's actually used to talk about why salt is causing the obesity crisis. So we have this dubious looking linear encapsulation of the relationship between salt intake and fluid consumption, which actually there's a long history of that belief, but it's now seems to be not true, and I'll talk about it a bit later. But it certainly doesn't look linear to me, but I'm gonna actually read what they say in this article because it's just so insane. Whilst salt is not a direct cause of obesity, it is a major influencing factor through its effect on soft drink consumption. Salt makes you thirsty and increases the amount of fluid you drink. 31% of the fluid drunk by four to 18 year olds is sugary soft drinks, which have been shown to be related to childhood obesity. Reducing salt intake could therefore be important in reversing the current trend of increasing childhood obesity. So there you go, salt causes obesity. Okay, so I don't think we really need to argue too much more about that, at least in this community, but a very influential book that has had impact in this community came out about five years ago that made a swath of claims in an attempt to support its thesis, which is that not only is salt not harmful, but it's actually harmful not to eat it. So examples of the claims, and I'm not gonna address most of them, include, for example, that a low salt diet increases insulin and thereby can cause insulin resistance, that because a low salt diet activates the reninate angiotensin aldosterone system, this could lead to heart failure and kidney disease, and it reduces sex drive and fertility, increases erectile dysfunction, sleep problems, et cetera. And then because if you think about that, it wouldn't be very evolutionarily consistent if we had a low salt diet in the past and it was causing all these problems to not get a very high amount of salt, right? So it all kind of hinges on this other claim that the book starts with that despite the majority of scientists believing that our evolutionary ancestors evolved on a low salt diet, the other claims that we actually evolved on a high salt diet. So these claims have actually been addressed extensively elsewhere and you can read some critical reviews here. The first one here is a fairly quick and actually quite decimating, I think, look at the quality of evidence that's used specifically in trying to make that claim that we evolved on a high salt diet. That's from Matthew Dalby, who I know through this community, actually. The second one is an extensive set of counterarguments to many of the other claims throughout the book and I actually don't think I agree with all of the counterarguments, but that article provides an amazing bank of studies. So if you wanted to look into any of those specific claims and see where the evidence lies, you could look and see all the foreign against for it that the person has put together. So I'm leaving that for an interested reader. But because all of these claims are not diet specific, they're all tied to the Western diet, it kind of makes it irrelevant, especially since a lot of the evidence has to do with either epidemiology or other kinds of observations in people eating a grain-based diet. And so it may not, even if the claims are true, it may not be transferable to what we are caring about. So I wanna just step back and look a little bit about the history and geography of salt intake across humans. It's definitely the case that in Neolithic times, post-agriculture salt became very, very important. There was an extensive salt trade. I think taste was probably a part of it. I mean, other things like spices and luxuries were traded extensively. But I also think that a great deal of its importance was for preservation as a kind of alternative to fermentation, which would have been the main preservation before that. So it's a huge new technology that was very, very valuable. However, beyond the agricultural world, even in the current times, if you look at other societies that are not agricultural, and here I've just selected a few examples of specific peoples that have been studied by various authors over the past 50 or more years, if you look at all of them, their salt intake was actually very low, ranging from almost nothing through a couple of grams of sodium adesum, in any case, much lower than what we're eating now, and to no apparent detriment. And this is carbohydrate agnostic. So some of these societies were eating almost nothing but starchy carbs, and others almost nothing but meat. And so just an example of the very, very low sodium from this study, this was actually a study about the flora and fauna in a particular region and how those animals and organisms were adapting to the low salt. But of course, if you go up the food chain, the people who live there also had very low salt as a consequence, and he says that the Highland Papua consumes 200 to 400 times more potassium than sodium, and to give you a sort of reference for that, a typical wild carnivore would eat 20 to one potassium to sodium and an herbivore would be something, sorry, five to one and 20 to one for herbivores. So this is much, much bigger than that in the absolute amounts, less than one, less than 0.1 gram per day. And they had aldosterone levels, which are consistent with what we would consider, or what they would have considered sodium deficiency at the time. And aldosterone comes into place, into play to conserve sodium in the body. And so this look to them like it could be possibly dangerous, but whether it's actually dangerous is kind of a point of contention. In fact, we saw earlier that Nicola and Tonya was claiming that it could cause heart attacks to have aldosterone that high, and when we look at the stance in the ketogenic diet community, it's thought to be causing symptoms that might explain people's belief that a ketogenic diet causes quote unquote adrenal fatigue. On the other hand, there are views like this. So this is a review about the effects of low salt diets as much more recent, 2010, and the author is looking at all the physiology, and he concludes that it seems like the sodium restriction is making changes in adrenocortical function relative only to salt retaining hormones. So it's increasing the production of aldosterone, but the available evidence does not suggest that this is associated with diminution in other adrenocortical function, and it follows that the ability to withstand stress should in no way be diminished by a decrease in the present general levels of salt ingestion. So in other words, his view is that the function of aldosterone is specific to maintaining salt balance, and it's just normal in a low salt context. And what I think these ethnographic studies show is that a low salt diet is normal. So if a low salt diet is normal, then maybe a higher aldosterone level is also normal. If we look at what people have estimated pre-agricultural sodium intake, it's also quite low. One person is estimated at below a gram per day, and cordane and colleagues say that there's minimal or no evolutionary precedent in the hominin species before the neolithic period of this 10 gram per day level of high salt consumption. So let's look at salt needs on ketogenic diets. Verda Health, where Stephen Finney and Jeff Bullock are advocating for and educating about nutritional ketosis, which they have done for a very long time, do advocate for salt, especially for ketoadaptation, which is a relatively short period, but then in an ongoing way for nutritional ketosis as well. And they make this interesting claim that I alluded to before that these symptoms that some people report when they're not feeling well on a ketogenic diet and they call it adrenal fatigue are exactly the symptoms that you would expect if you had a sodium deficiency. But they argue this on two premises, and the first one, I'm not really enthusiastic about it. It's an epidemiological argument, so they have this chart showing a mortality curve based on salt excretion from a certain day, and then based on that, in a grain-based population, they say that five grams, which is what they recommend, is the sweet spot for salt intake. But I just, I don't find it very compelling because I don't think that this kind of information can tell you anything about what's best on a ketogenic diet, even if it is relevant to a grain-based diet. But what's a bit more persuasive to me is their talk about the naturesis of fasting. That's sodium urine excretion. There's a long history of literature on that from fasting which translates somewhat to the ketogenic diet. And so I'm just gonna point to a couple of landmark studies along the way of the topic and things that they pointed out that are informative. So there's this very early study, one of the earliest in 1960. They're looking at here a comparison between the sodium excretion during a four-day fast compared to four days of a very low sodium diet. The low sodium diet is the very steep one where the excretion is very high at first, which is kind of counter-intuitive. But then it drops off very quickly. Whereas with fasting, it starts out about the same also very, very high and drops off a little more slowly. The reason that they were looking at this actually wasn't so much to compare it to the low-salt diet although they knew that was of interest. But it's because they had noticed, people had noticed that when you fast, you lose an enormous amount of weight at the very beginning. And we all know now that that's water weight. But one of the reasons that we know that is from studies like this. And what he says basically in the discussion is that this weight loss happened even though people were drinking as much water as they needed. So it's not altering some kind of normal mechanism for maintaining isotonicity of the body fluids. That means for keeping the concentration of salt and water in the extracellular fluid that has to be kept in a fairly tight range. He says, it seems likely that the changes in fasting would be of such a nature as to provide the optimum physiologic adaptation to this metabolic state. So in other words, he's saying that we're excreting salt so that we can get to the level that is more appropriate for this particular condition. We're not losing salt that we actually needed. And he goes on to say that maybe in our modern context with so much salt availability, we have this great excess and the excretion is just to kind of reset to what our extracellular fluid is supposed to be under that different state. Here's another study that I think is really interesting because what they've done in this case is they've done, it's just three days of fasting again, but they've done different levels of sodium intake. And so they're kind of trying to make up for the excretion. So they have 50 mil equivalents and 100 mil equivalents. 100 mil equivalents is about two and a half grams of sodium, a little less. So it's like a teaspoon of salt. And what you see is that over time, over three days, the excretion goes to match and exceed what's being given. So if you're given 100, you excrete 140. If you're given 50, you excrete 100. If you're given none, you excrete 40. And so the balance seems to maintain around this negative level. And so it seems like we're kind of chasing an excretion and it doesn't really benefit you to try to add more. Here's a study where it shows what happens if you let this go on longer. And it looks like it takes about a week for that high level of excretion to stop and then you go into approximate balance. You still need a little because you still will need some sodium replacement even no matter what condition you're in. So the balance isn't completely zero, but it settles out. And I think that supports the idea that in an ongoing situation, the body can adjust to these lower sodium levels. And then there are studies showing what happens when you try to add back food. So in this one, the two bars, one's sodium and one's potassium. And the dotted line that's higher is the sodium intake that they were given. And so we've got control as before the fast. And then an average of what happens over three days of fast and then refeeding with 600 calories of various macronutrients. So if you eat carbohydrates after that fast, you'll immediately go into positive salt balance. And in fact, it's not shown here, but that positive balance goes way higher than normal so that you're retaining a lot, which can possibly be a problem for some people. And when they added protein back, it went to almost neutral. And when they added fat, so made it even more ketogenic, but without any actual protein or carbohydrate or ability to add carbohydrates, the excretion went even higher. And then just another example of that, we've got a five day fast where you can see that the peak excretion has already been hit and is starting to come down. And then when they add protein, it just goes right into positive sodium balance. And so that can maybe shed light on what would happen if you were in the context of an actual ketogenic diet and not just fasting, which is obviously a bit different. And again, so this sentiment gets repeated. These authors say the naturalistic stimulus of fasting can be a profound one and it continues until an appreciable degree of contraction of the effective extracellular fluid volume occurs. And after this initial phase of naturesis, avid sodium retention is the rule. So maybe there's just an excess sodium required to support all that fluid that's not present in the fasted state. So the story looks like this, you start a ketogenic diet and that leads to a release of extracellular fluid and a negative sodium balance, despite intake, regardless of what you do, until you reach a new balance level. And the standard of care says to respond to that acutely with supplementation. And as far as I can tell that the excretion's just gonna exceed it. Okay, so I also just wanna point out from an evolutionary perspective, we're talking about a very old conserved metabolic state that originally was an adaptation for lack of access to food. And I would think that when you have lack of access to food, you also have lack of access to water and almost certainly little to no sodium at all. So if you believe that humans and prehumans were fairly frequently entering ketosis for millions of years, then it would seem strange that a sodium excretion here is a mistake that we need to correct. Now it could simply be that it was a necessary cost and that fixing it is actually better than not fixing it, but it's not necessary. It's hard to tell. All of this is very connected to water needs. So this is a graph from Kay Hill who was an early study of fasting. And he is pointing out that when you fast, your urea generation goes way, way down. This is not necessarily true if you're eating protein, but because of that, you don't need very much water to excrete it. And he says your urine volume can fall to 200 milliliters per day. But there's a second component here and that's that when you're eating that or consuming when you're metabolizing, let's say from either food or from your own body stores that much fat, you're also beginning to actually produce a significant amount of your own water. So let's look at metabolic water a little bit more. So despite what you may have heard, when we metabolize fat, we don't turn it into energy in a sort of matter into energy sense, right? There is an ATP byproduct, but the mass itself gets transformed into carbon dioxide and water. And we never talk about that usually because all we care about is calories and water and carbon dioxide don't have any calories, so why would we even talk about that? But we do get water out and that's pretty significant. If you're eating or losing from your body, say 200 grams of fat a day, which is quite plausible on a ketogenic or fasting situation, that's your 200 milliliters right there because a gram of fat will give you a gram of water approximately. If you're eating protein, you might need more than that. So it turns out that it's not just the case that burning fat can meet some of your water needs, but actually having water needs can cause you to increase your fat burning for the purpose of generating water. And I know two ways in which that can happen. First is not drinking. So there's this really cool study with birds, migrating birds, finches who are fasted overnight with and without water. And the take home is that when they didn't give them water, they burned six times as much fat to make those water needs. So that might be one reason to not drink water if you're fasting and you're really interested in fat burning. But the other, oh, and I wanted to mention that there are other animals that do make pretty much all of their water needs are met through their own metabolic water in addition to whatever they get in their food. And that would include some desert animals and hibernating mammals and some marine mammals. And the question comes, well, how much does that apply to humans? And it does, there is an interesting fact that it appears that humans have an adaptation for reduced water demands compared to other great apes. And that's a newish paper from Ponser and colleagues. But the other way that you can cause metabolic water to be made is by consuming salt. So like I said earlier, it used to be thought that high salt intake drives thirst. And that was thought for a really long time and that was what was behind that soft drink claim. But that's now thought to be false. There was a really interesting paper that has many components to it that I would love to tell you all about but I'm just gonna tell you the one part that's relevant here. And that's that they found out that giving people high salt intake, it didn't cause them to drink more but it caused them to break down like it caused a catabolic state with cortisol and the more breakdown of fat and protein that led to more metabolic water. So it causes water retention in various ways. So this looks in many ways like water balance changes in keto adaptation and in dehydration. So maybe that's also a reason to try to consume salt. So you can drive fat oxidation by playing with those osmolality needs to keep your salt concentration in balance. To look at the other side, does drinking more water increase salt needs? It's not clear to me that it does because I think that we can regulate our excretion of water equally well but there may be certain athletic situations. Tim Nokes has a whole book about this called Waterlogged in which there can be a lot of danger from drinking a whole lot of water that's not properly salted in the athletic community. And it's not from sweating because sweating is actually a hypotonic, you sweat more water than you sweat salt so it increases your salt concentration. So let me just quickly go on to the carnivore diet. The most, the two most important figures of the modern carnivore diet community were these two figures. One is Wilmer Stephenson, he was an Arctic explorer and he stayed with the Inuit for six or seven years in aggregate and ate what they ate and that included low salt so he thought that that was pretty important. And Auslie Stanley who is this eclectic sound man for the Grateful Dead, LSD, Cooker, extraordinaire, ballet dancer is just really amazing guy and he ate a pure carnivore diet of all things for the last 50 years of his life and he had certain things that he believed about it for whatever reasons and he was adamant that salt should be avoided. And so those two people really influenced the culture that I cut my teeth on when I started the carnivore diet and that's part of why we didn't use salt. So why might that be? We know that salt licks are something that herbivores go to and carnivores only go to to get the herbivores, they don't really partake in it themselves. So what could it be about plant eating or about meat eating? What plants are very high in potassium which can increase your sodium needs. Another thing that's not talked about very often is that plants are full of secondary metabolites, anti-nutrients that need to be detoxified and that can take sodium. So there's some evidence that animals that go to salt licks will go to them more often if they're eating plants that are really high in certain toxins. And then on the meat side, meat has much more sodium than plants. So carnivores typically get all of their sodium needs met simply through the meat that they eat. So for a carnivore diet or we have those three reasons at the top and then I also speculate that it possibly has to do with drinking less because on a ketogenic diet you're often drinking sweetened drinks or some kind of, or you're encouraged to drink high levels because you're dieting or something and you don't really drink to thirst. You drink for the reasons of pleasure or for reasons of belief in health needs. Whereas if you're on a diet where you're said told to drink only water and drink it to thirst you're much less likely to over-drink. So maybe that is a component. What about people who just cry a lot? Not, I'm joking. So I can't tell you how much salt is optimal for you. I think there's a lot of individuality. I've seen some people who absolutely feel their best when they're eating a lot of salt. And I've also seen a lot of people who took salt out of their diet and suddenly feel way better than they ever felt before. So all I can really do is point to these patterns and see if it's helpful somehow to figure out why those things might be true. And it's interesting to notice that the only two groups that I know of that have this high salt intake are this agricultural grain-based diet and the ketogenic diet. One for, I don't know, historical reasons and the other, well, also for historical reasons. But these are the factors that I think might have something to do with it, water intake, plant intake, meat intake, and culture. And so I hope that that's useful for your own self-study. Thanks. Thank you, that was a great presentation. Your conclusion seems spot on, especially given that thirst and sodium intake are so regulated at a very basic level, you would expect that the thirst for water and taste for sodium would be the ultimate determinant of someone's needs. I had one comment and one question. So you showed each carbon generating one, accounting for one water molecule in metabolic oxidation, but that neglects the two water molecules that are consumed for each carbon in the complete beta-oxidation of a fatty acid, which is a loss of water. So one water for each acetyl-CoA generated in beta-oxidation is consumed and then three waters are consumed in the citric acid cycle. So I'm not sure that beta-oxidation can actually account for that metabolic water. But my question is on these ethnographies. So I don't wanna seem like I'm dissing ethnographers, but it seems like ethnographic research has its fair share of extremely sloppy, missed observations that seem obvious to those of us whose primary concerns are nutritional. So two things that come to mind are the people who estimated that the Hadzi ate 150 grams of fiber a day because they neglected to note that they spit the fiber out into the dirt. And the people who estimated that the Zimani eat 96% carbohydrate, which is a high carbohydrate diet, but they only measured what they brought back to the camp and didn't measure anything that they were eating when they were out hunting. And so earlier in this conference, two days ago, I think Pedro Carabastos noted that stuff in Lindemburg noted that in their cooking water for their tubers, which is consistent with what you were saying about a high carbohydrate diet needing more sodium, they would include enough ocean water that they got 2.3 to three grams of sodium per day from it. And so what are the chances that these ethnographies have missed something like that when they've been studying it? I wonder if you have any comments on that. Yeah, thank you, Chris. Those are excellent comments. So about the metabolic water, I admit I didn't check that work. That seems to be the standard answer when you look around. I would counter that with the fact that tissue, the adipose tissue might also have water in it that gets released when it's burned, but I don't know what the actual, if that calculation is actually off. As to ethnography, you're absolutely right. Not only do we make mistakes, but we see what we want to see. And so if low salt was considered some kind of panacea, then it would be natural for people to overlook sources. So those are excellent points, thank you. Hi, Amber. Hi. Regarding the point that you made that sweat is hypotonic, I'm a little confused at that point. If I understood you correctly, it would seem to turn a lot of sports nutrition and hydration completely on its head. And that actually, if you're retaining more salt than you are losing fluid, then replacing it with water would seem to be completely adequate. Right. And so I thought that maybe the situation could be that instead of talking about like perhaps a purely assault depletion or overabundance, that maybe it is more of a, that we're missing things like magnesium or potassium, or there's kind of just maybe an imbalance in the way that we feed ourselves in modern diets. Right. So yeah, I think you're absolutely right that the whole industry is dependent on that belief. That's partly what Tim Nox's book is about. And there is a variance in the amount of sodium that's excreted in sweat, but it seems to be related to how much you take in in the same way that urine excretion is higher if you take in a lot. So if you say, well, you're losing all this salt in your sweat, so you have to replace it, that might actually just be a feedback of with the wrong causality. But I've also seen some people point to genetic differences. And you're absolutely right, we lose all kinds of other things in sweat like Lisa was mentioning that we lose iron and sweat. So maybe more complex than I put it. But I do think that it does have huge implications for our practices in endurance sports. And one of the things that Nox points out is that persistence runners in societies that do that go to great pains to not use a lot of water on their runs, because carrying it is a detriment. They need to be as light as possible. And combining that with noticing that humans seem to have this extra ability to need less water, it's kind of plausible to me that we're over drinking in our exercise. Right, thank you, Amber. Good presentation. Thanks. Amber, great talk. I have a question that I guess is kind of selfish because it's really for my own benefit after this, five grams. I recently read a book from Rick Johnson at the University of Colorado, why our nature wants us to get fat for some of the longer lines. And he talks about this pathway, which I'm gonna butcher, especially after following a question from Chris, but he says something along the lines of, if you have a high blood osmiality that it's gonna trigger this polyol pathway that's going to push glucose and form fructose, which might lead to increases in obesity as well as uric acid, which might have the connection to blood pressure and stuff like that. So my selfish question is, I'm a guy who saunas or goes on a hike or something and I'll come home and rehydrate with an electrolyte package that has high sodium of some sort. And I'm wondering if that'll put me in a state of high blood osmiality that if I go have a sweet potato or something thereafter, am I actually really driving that pathway or? Okay, yeah. So I actually had some slides on uric acid that I had to cut, because I've talked about uric acid here before. And one of the hypotheses that I didn't really talk about much on that talk was the blood pressure hypothesis. And specifically because we were in this low sodium environment that we needed that uric acid to bring blood pressure up. But the other thing that I went into in that talk was that the idea that there are these pathways that lead toward the metabolic syndrome kind of pathways don't seem to necessarily be relevant in the context of a healthy, metabolically healthy person who doesn't already have some kind of diabetes going on. And so while I think it's true that especially in someone who's already on the path to diabetes, that that polyel, the fructose generating pathway would become triggered, I'm not necessarily worried about it in someone who is otherwise healthy. Awesome, cool.