Is A Ketogenic Diet Harmful Over The Long Term?


Welcome to Better Brain Fitness, hosted by doctors Josh Turknett and Tommy Wood. In this podcast, we will explore the frontiers of how to keep our brain fit and healthy so that we can perform at our best and do the things we love for as long as possible. Let’s go. Hello and welcome back to the Better Brain Fitness podcast. My name is Tommy Wood and I am joined by my low carbohydrate host Dr josh Turknet hello Josh, Hello Tommy.

00:36 : I joke but mainly because of today’s question that Josh is an expert in and is going to going to tackle. Today’s question is from Simeon in New York. Who says I am on a ketogenic diet? After reading your book The Migraine Miracle, I have read articles here and there by other medical professionals saying it is a dangerous or unhealthy diet in the long run. I don’t intend to switch back anytime soon as going keto all but erased by migraines, but I would appreciate your comments. So Josh, what are your comments? All right, I do feel a little triggered by this question and your description is fair of me at least the perception is that I’m the low carb and keto guy, for better or worse, cuz I have promoted those tools in various ways.

01:31 : So this is a good question because I know it’s one that’s out there anybody who’s you know in the world of keto at all and it’s been online is going to encounter all sorts of opinions about it. And it’s an area where we, both of us have quite a bit of experience and there’s a lot of places we could go answering this question we could, this could be a 12 hour conversation if we wanted to. But just to kind of zoom out, I think part of the issue here is that anything that becomes popular, especially popular quickly, like keto has, is going to invariably invite attention and detractors, that’s just a super common, an old story.

02:10 : And I would say just first and foremost, as a general rule, anyone who makes a statement like that, you know, keto is unhealthy. Keto is dangerous, something that broad and referring to a ketogenic diet as if it’s some kind of single monolithic thing either doesn’t understand the subject or maybe has some ulterior motive or reason to kind of dispense some misinformation about it. Unfortunately, that probably describes the vast majority of things written online in health and nutrition. I’d see it say it’s also likely true that if someone is making a statement like that they haven’t been in the position of using ketogenic diet with patients or clients first because they probably have the expertise to know that it’s you know, it’s too broad and ultimately A nonsensical kind of statement but they’d also have first hand experience with what actually happens to people’s health and well-being And again, so the statement itself is kind of so broad and general that it becomes meaningless and that’s not the fault at all the questioner here because you see statements of that kind, this kind of nature all the time so the problem here is that when we say someone is eating a ketogenic diet, all we really mean is that they’re eating in a way that stimulates nutritional ketosis.

03:28 : But there are literally an endless number of ways to eat that would accomplish that. So in some ways, it’s kind of like saying walking is dangerous, right it all depends on where you’re walking. And a house in a grocery store, on a freeway, on a tightrope. And there have indeed been studies, you know, on people who’ve been on a ketogenic diet over the long term that say it’s safe and not dangerous. But I don’t even like to really cite those because it’s, again, kind of too general a question to be useful. It’s like saying we did a study on walking and found that it’s safe. It still doesn’t mean it’s safe to walk in the freeway or to walk on a tightrope, right? The specific details are going to be everything in a question like that.

04:13 : And yet those kind of details are lost when we study things in these broadways. So it’s always going to depend on the individual cases. And as we’ve discussed, there really just aren’t, these aren’t questions that we can answer with our existing research tools to answer in individual cases. So first I’m going to back up, just to give a little context of why this even matters. You know why we’re talking about a ketogenic diet i imagine most people have heard of the term, but probably there are varying levels of familiarity with it. So as I mentioned, the goal of a ketogenic diet is really to just stimulate ketosis just to stimulate the production of ketones by the liver, which are then reduced into the bloodstream.

04:56 : If you want to get really technical, you’re trying to reduce the production of oxalyl acetate, increase the reduction in production of acetyl Co A, which is a breakdown of fats so that you are diverting. It’s so that some of that acetyl Co A can’t pass through the Kreb cycle. It’s then diverted and converted into ketones. And this is just a very elegant mechanism that our body has of shifting our source of energy depending on what we have available, whether we have a lot, you know, carbohydrates available or not or whether we need to run on fat.

05:29 : And it’s, you know, certainly been a mechanism that’s been critical for our ability to survive and thrive for you know millions of years. And that’s largely because when we have ketones circulating, our brain can use those as an alternative use fuel source instead of glucose. And that you know when the brain is using ketones for energy, it can have a very positive impact including in certain clinical conditions like epilepsy, migraines is the original questioner i was talking about mental illness as well as potentially preventing and treating certain neurodegenerative disorders like Alzheimer’s and Parkinson’s. In a recent episode, we talked about the evidence showing that in Alzheimer’s there’s impairments in the ability of brain cells to utilize glucose for energy so ketones can potentially improve cognitive function in that particular situation by acting as an alternative energy substrate that the brain can is better at using.

06:35 : The very first uses of the ketogenic diet were in children typically with intractable epilepsy. So these are kids who were having, you know, who would have very frequent seizures, nothing would really help and this was back in the early twentieth century and it was very found to be very effective, but it requires for most people an increase in their intake of dietary fat. And so once people started become scared of fat kind of mid search mid twentieth, century the ketogenic diet started to become viewed as something extreme. And I think that we’re kind of still dealing with that legacy.

07:16 : So the a lot of the concerns that you see are more an artifact of the history of keto rather than something that kind of comes directly from the science of it. And we’ve come a long way since then in terms of the science, but we’re kind of still dealing with that fallout. The Qgen diets also, you know, really helpful for metabolic disorders like obesity and diabetes and so many cases of Type 2 diabetes being effectively cured by it. So bottom line is it’s this enormously powerful intervention or tool that we can use and, you know, can transform people’s lives and already has relieved, you know, countless hours of suffering.

07:55 : And I know this first hand in working with people with migraines and epilepsy, as does the Simeon who asked the question. And in fact she voices what is the most common response to someone trying to say scary things about keto, which is, well, it doesn’t really matter because it’s helped me so much i’m not going to do anything differently. And you know the effects you know that we see in these in clinical instances likes epilepsy and migraine are far greater than any drug that we have. An illustration, just the fact the food that we eat is just a much more powerful tool. And I think it also highlights just how much more we stand to gain from fully exploring and utilizing lifestyle interventions than we do with pharmaceutical interventions.

08:42 : So I think anyone who should think very long and hard and make sure they really know the whole story before they try to dissuade someone from using a ketogenic diet or especially trying to encourage someone who’s benefiting benefiting from it to stop. Hey there. So if you like this podcast then I think you will enjoy the Brain Joe Connection newsletter. The Brain Joe Connection is a free newsletter sent out twice a month and is all about the science of how to keep our brain fit and healthy, along with products, books, tools and resources for improving brain health and function that we use and recommend.

09:22 : To subscribe. You can go to brain Joe dot Academy forward slash connection or click the link in the podcast description. All right, now back to the show. If we take the statement just that a ketogenic diet is dangerous over the long term at face value. And really, the claim that’s being made there is that circulating keen tones are harmful in the long term. That, you know, even though they have these beneficial effects in the short term, perhaps having them, you know, for longer periods of time is harmful. And I don’t think there’s any reason to believe that to be true. And I think you’d be hard pressed to find anyone with expertise in this area who believes that to be true, that there’s some something harmful about having ketones over a long period of time.

10:08 : And back to The Walking analogy, you know, the act of walking itself is not dangerous at all it’s quite good for you, in fact so I think you’d likely find most people saying the same thing about ketones. Now, as I mentioned, there are an endless number of ways that you could eat that would put you into ketosis. So two people can be eating a ketogenic diet quote and be eating an entirely different set of foods, and it’s entirely possible to eat a very nutrient poor diet that stimulates nutritional ketosis you know, you could eat nothing but Crisco and you’d stimulate ketosis.

10:46 : So in that case, yes, on balance, the diet is not good for their health, for their health. And that has nothing to do with the ketones themselves, right the ketones are still beneficial, but it’s the net effect that’s negative in a case like that. And so again, we’re talking about a very poorly formulated ketogenic diet, which I wouldn’t advocate and not something I’ve ever used with patients. And again, this is like walking on a freeway or on the side of a Cliff, right? Even though the benefits of walking are still there, the net effect is that it’s still hazardous to your health.

11:19 : Now the reality is, I think that most people who switch to a ketogenic diet from a standard Western diet end up actually improving the nutrient quality of their diet because for most it requires removing refined carbohydrates as a source of calories, and those typically comprise a significant proportion, in many cases the bulk of calories in the standard Western diet. And those foods that are high or fired carbohydrates are some of the most nutrient poor things that people eat.

11:51 : So in the majority of cases you’re going to be replacing foods of low nutrient quality with foods of higher quality. So let’s then try to take the most kind of charitable view of this kind of objection and maybe consider some more informed potential areas of concern about keto. One reasonable question I think is restricting carbohydrates, you know, okay to do, especially over the long term. So as mentioned, you know, eating a ketogenic diet, stimulating ketosis does require, you know, being mindful of carbohydrate intake and also requires eating a certain amount of dietary fat. The amounts and in what ratio is going to vary a lot from one person to the next.

12:36 : But those things are still generally true. So the question is there any reason to be concerned about restricting carbs in general as a macro nutrient? And the answer to that is no. There aren’t any essential carbohydrates, whereas there are essential fats and protein, and we’ve known this for a very long time. Another thing that I’ve seen, you know, bouncing around the Internet is that keto is dangerous because the brain has to have glucose. And some instances of the claim is that the brain only uses glucose for energy, which we know to be absolutely false, but the brain can run on ketones instead of glucose but even on a ketogenic diet, it’s still only providing about 60 to 70 % of energy needs, with the other still provided by glucose, since the body can actually produce glucose in the absence of any dietary carbohydrates.

13:26 : Second potential area of concern, what about its impact on the gut, specifically on bacteria that produce a substance called butyrate? Butyrate is Purdue is a food for our gut cells or colonocytes and it also helps with gut barrier function. And so there are bacteria in our gut that are fed by the fiber in our diet and then those bacteria make butyrate. And again, I think this particular concern also largely stems from treating ketogenic diet as this monolithic thing. Because one thing you may hear is that or a common misconception is that it is a low fiber diet.

14:14 : And so you’re removing fiber, less fiber to feed these gut bacteria. When the reality is that you can consume lots of high quality fiber on a ketogenic diet since most green vegetables have minimal carbohydrates. And so again, in many instances, people will end up actually eating more fiber than on a standard Western diet. But again, you can stimulate ketosis without eating any plant matter. But now we’re back in the realm of just a poor quality diet. You know that’s has nothing to do with ketosis, right? And there’s no reason you can’t eat plenty of it on a ketogenic diet.

14:51 : Now, it’s actually still an open question as to how much, if any, fiber you do need on a ketogenic diet to produce butyrate as there’s reason to believe that our need for computer rate production from dietary fiber is diminished on a ketogenic diet, which I believe Tommy wrote a paper about, so I might let him fill on the details on that topic in a minute. And then the other area of potential concern gets back to the issue of the great fat scare is the impact on cholesterol or blood lipids.

15:26 : And again, this is going to be a scenario that you know anybody who’s worked with people is going to be no, it’s entirely dependent on what people are actually eating in a well formulated ketogenic diet. Most of the time you’re going to see improvements in lipids. You’ve been using very well established metrics. But again these effects are going to be individual. So you’d have to kind of look at things this particular issue on a case by case basis. So back to the main question, any reason to believe ketosis itself is dangerous over the long term? no.

16:02 : If we take the ancestral view kind of think about what would maybe have been the most common pattern that we that metabolic pattern we had over tens of thousands of years. It’s likely that we spent long periods of time in ketosis. So you know, a natural way to mimic that if you were to look sort of using the ancestral template, would it be to take a seasonal seasonal approach where perhaps you were in ketosis, lower carbohydrate in cold, colder months, and then you increase consumption in summertime as more fruits are available. I think a more interesting question is rather than whether it’s dangerous, is whether or not a well formulated ketogenic diet is optimal.

16:48 : And that’s probably a question for maybe a different pot, different episode. I think there are definitely scenarios where longterm use is probably optimal. Optimal you know, for certain clinical conditions and will hopefully get better at answering that question in coming years. So it may be optimal longterm in neurodegenerative disorders or in prevention for those who are at high risk. Another interesting area of debate and in area of research is in its use for athletic performance where you know, you might cycle and out of it as a means of kind of optimizing your metabolic machinery, you know, depending on your performance goals.

17:30 : And those answers are going to be very sports specific. But again, that’s a very different issue than the one raised. All in all, the fundamental answer to the question is it dangerous i will have to say definitive no. And I’ll turn the floor over to Tommy to see if he has any anything else to add, including any comments around the whole fiber butyrate issue. Sure, I can start there. I did write a paper on this with my colleagues Jonathan Scholl and Lucy mailing about this a couple years ago. And it’s very interesting that whenever studies that look at changes in diet, how that affects the gut marker bio so how that affects what the microbiota produce, things like butyrate that are known to support gut health and function.

18:26 : They’re always looked at from essentially the same slant that you have just described that there’s this assumption that fiber is necessary and meat and animal products are bad for the guts. But when you really look at the papers and their data, they don’t necessarily show that at all. And instead what they show is that if you make large shifts in your diet, your metabolites and what you use from your food to support gut function also shifts as you would expect. So you can make ISO, short chain fasci acid, so related to butyrate, but not the same as butyrate from protein instead and they can be used by the gut and you and the gut can also use some metabolites of fats for energy as well as ketones from the bloodstream you know from the from the other side.

19:20 : And all of those go essentially enter in the same common pathway for energy production as butyrate does. So the real summary from our paper was that the gut is inherently metabolically flexible or at least it should be which makes sense from an evolutionary standpoint because you want your gut to function regardless of what food you can get your hands on, which is going to be highly variable from you know what way you are based on latitude and season and all the things that you already mentioned.

19:50 : And so I think that that’s a really important takeaway point and that the brain largely is the same it can run fully on glucose or it can shift to majority ketones so not entirely ketones it based on the food that you are or aren’t eating. So that’s just I think that’s part of what allowed humans to occupy all the all the niches around the world that we did is the fact that almost all of our organs are very flexible in terms of the metabolic substrate they can use and.

20:23 : Be perfectly healthy. Doing so it’s a really important point to say that how you get into ketosis is matters and it’s also very, you know, there are just so many ways to achieve that because often you’ll have people who say on the one hand the ketogenic diet is dangerous, but hey, fasting is really good for your health, yet both of those end up with you being in nutritional ketosis. So then, so there’s definitely a huge amount of nuance in terms of how that’s achieved.

21:00 : One thing that you didn’t mention but people will probably be interested in is exogenous ketones or ways to get into ketosis exogenously. You can either take ketone salts or ketone esters ketonesters in particular are very rapidly converted into ketones and can elevate blood ketones quite you know very quickly and also to quite a high level, the kind of level you wouldn’t get into unless you fasted for you know days or weeks and then a medium chain triglycerides are the other way which are shorter chain saturated fats that get absorbed slightly differently and they go straight to the liver and they get turned into ketones.

21:41 : And in terms of cognitive decline, the best evidence is actually in that arena, although it’s still there’s still really early on in that and I’ve seen debates in the neurology world where people talk about ketosis or not for Alzheimer’s disease or Congress a decline and some will say you know there’s evidence that is beneficial and others will say, well actually there are no, you know, really good high quality randomized control trials and essentially both groups are right. That’s just where we are with the evidence right now so there are, there are some small studies done by people like Stephen Kinane where he gave I think he was 15 grams of medium change triglycerides twice a day for several months.

22:26 : And they had a placebo group and they saw that in the medium change triglyceride group they had improvements in various aspects of cognitive function and this was associated with increased ketone uptake into the brain so the brain is getting that energy substrate from the supplement but you know this is not on the scale that we would require to say you know this is what we should be doing for all people with Alzheimer’s disease or mild cognitive impairment. Another area or you know group that have maybe shown some benefit here is Dale Bredesen and his group.

22:59 : They use a diet which they call the Keto Flex twelve three diet which is largely plant based with some animal protein but it’s relatively low carbohydrate and people get ketosis partly because there’s an extended the time restricted eating components so you only eat within a maximum of 12 hours a day and you don’t eat for at least three hours before you go to bed. But this is all rolled into Bredesen’s wider recode program which includes a whole bunch of stuff that they intervene with and they’ve shown some benefit again in small studies so the diet may be playing a role there.

23:38 : However, other studies where they’ve just reduced the glycemic load of the diet in people with cognitive impairment has shown benefits so you’re not generally restricting carbohydrates, you’re just improving the quality of those carbohydrates and decreasing blood sugar spikes we’ve talked about blood sugar control being really important for the brain and in those diets you may even get into mild ketosis the in the morning before you before you break your fast you could be 3 or 5 milli molar of beta drugs, butyrate, that’s very normal and that’s also seen in more ancestral or hunter gatherer populations, even those who eat a reasonable amount of carbohydrate, they are in ketosis often first thing first thing in the morning because they eat a very low glycemic load and low total load of carbohydrate in general compared to say a standard western diet which is just all carbs all the time.

24:35 : So I think hopefully that provides some additional nuance to the question. My final arena was and I think this is where people are what they really mean when they say that a keygenic diet is dangerous is related to cholesterol and saturated fat intake. For a long time there was this big push in the in the keto world, the people would just eat fat bombs, which was essentially nothing but saturated fat.

25:06 : On average, that’s going to increase your LDL cholesterol, your or your APO B containing like proteins, which are the ones that are thought to be atherogenic or to drive, you know, plaque atherosclerosis in your arteries. And in general I’m not entirely sure that deriving the vast majority of your calories from that kind of food you know chugging heavy cream and eating whole sticks of butter all of that is nutrient poor. It’s you know there’s no protein in there. I’m, I probably wouldn’t advocate for that kind of Keith genic diet and I don’t think you would either Josh. So that’s a valid concern and it is worth like it is for everybody it’s worth looking at your lipid levels.

25:57 : I think we’re at a point where we can say that Applebee containing live proteins are necessary but not sufficient to cause atherosclerosis. And there’s definitely an interaction with overall metabolic health. So those who are in very good metabolic health seem to have less of an effect of having higher cholesterol levels. And this is something that’s still being passed out i’m part of a study as in part of the investigations on the study that are looking at this people who’ve been in ketosis for a long period of time who have very high cholesterol levels, looking at their arteries over time and seeing whether they’re developing all this plot like everybody says they should, but they’re otherwise in pristine health.

26:46 : So I think we’ll start to answer some of these questions. But if you went into a kestogenic diet after a long period of time of very poor health and your arteries are already in bad shape and then you your cholesterol shoots up and I think there’s a valid potential concern there, but it’s largely theoretical until you actually do some testing. So somebody who just tells you blanketly this is bad for you, I think you can go and get some hard data, ideally a c T coronary angiogram or you can do a coronary RT calcium score and there are some companies that can then convert that into a more detailed scan to like clearly to kind of give you a real picture of what your arterial health looks like and whether that should be something that’s of concern to you.

27:33 : And so my main takeaway here is that we’re reaching a point where we have access to tests and information and data that’s not particularly expensive they can actually allow you to decide whether, say, a large jump in your cholesterol levels because of a kestogenic diet is a net negative. So people who are talking in generalities, keysgent diets are bad for you, saturated fat is bad for you, meat is bad for you. As you will often hear against keysgent diets, I would just say, well, let me collect my data and then we can figure out whether that’s true or not.

28:09 : At a population level. These are things we’re thinking about. But for an individual, you just don’t know until you until you look. So if you did go on a keysgent diet and you saw a massive increase in your cholesterol, it’s worth, it’s worth thinking about. You know, if you’re worried about heart disease risk, it’s worth doing some additional testing to really figure out whether that’s something you need to be concerned about or not. So I think all of these aspects of nuance are really critical in order to answer this question for you as an individual.

28:46 : I think that’s it. Yeah i agree to your point about, you know, the sort of proliferation of bad versions of a ketogenic diet, you know, that emerged as it became more popular. That was kind of the reason I ended up writing a book called Keto for migraine. It was because, you know, it starts to get popular i know it’s this really effective tool however, the way it’s being promoted commonly, you know, people were to follow that would actually be worse for their migraines, you know and now we’re seeing that And so you’re kind of like, you know, again it gets to this issue that’s like you know extracting out the effects of the ketones themselves with all of these other variables that are changing.

29:30 : And so it’s all about the, it’s all about the net effect And so you want to, you know you want that net effect to steer in the right direction And I think both of us would advocate for an evolutionarily appropriate ketogenic diet as the way to kind of implement it. One other one other question for you that just short answer. If someone comes to you says you know I’m I’ve been on a ketogenic diet for a while you know maybe you know helping with some you know issue they were having.

30:06 : It’s a well formulated ketogenic diet. I’m not you know health markers are all good. I’d like to do this for you know indefinitely do you have any anything you’re going to say to caution them against that? No OK. I mean that’s what I’d say too i just curious to see but it is also worth saying that the other side is true if somebody comes to me and they’re eating very high carbohydrate diet, you know, even if they’re concerned about cardiovascular disease, Alzheimer’s disease, they’re eating a high proportion of their of their food comes from carbohydrate containing foods.

30:42 : You know, or you know they’re eating several hundred grams of carbohydrate today, which I, you know, lots of people I work with. That’s the case. Everything looks good, they’re in great shape, they feel good. Is there any reason I would caution them against that? no. So i think one of the most interesting things to me is that so many people thrive on a wide variety of diets. And the main thing is for me, and I also think for you, is the overall pattern of the quality of the foods.

31:13 : If the person eating a high carbohydrate diet is getting it mainly from, you know, gummy bears and French fries, then I would probably have a conversation with them about that just like if the person eating a huge Janet diet is mainly, you know, eating sticks of butter and chugging heavy cream, right? Neither of those are going to be good for the health long term, but there are there are ways that you can do those macro nutrient distributions in a way that can absolutely support your long term health, right. It’s all about the quality of those calories, right i mean, i think we probably would all be better off if we could like stopped even just talking about macro nutrients at all except for except for protein.

31:59 : Stop talking about fats and carbohydrates and just focus on nutrients. Yeah, yeah. But all right, agree with that as well thank you, Simeon for that question great one. I would imagine this conversation could invite some followup questions so please feel free to send those our way or any other questions you have for us on the topics of brain health, fitness, go to And that’s it for this one we will see you guys in the next episode thank you, Tommy. Thank you. Thanks so much for listening to Better Brain Fitness. If you’d like to support our efforts and help us spread the word about this all important topic, you can share this podcast with someone else you think might like it.