Dr. Rhonda Patrick: Okay, this is— I want to kind of shift gears and talk about some hot topics, I guess, in the fitness and health world.

Dr. Layne Norton: Let's do it.

Dr. Rhonda Patrick: Yeah, starting with seed oils.

Dr. Layne Norton: Oh boy. This will be the most commented section of this podcast.

Dr. Rhonda Patrick: Well, it's an interesting one. I avoid them. I try to mostly avoid them. I mean, at home, olive oil is what I use for cooking, for everything. But I also think they've been overly demonized in the fitness and health world. And I know that many of our listeners that are listening, watching, have heard a lot of conflicting information about seed oils. But maybe you could start with just summarizing what seed oils are and why are they such a controversial topic?

Dr. Layne Norton: Yeah. Seed oils are generally polyunsaturated fats, which means they have multiple double bonds, versus monounsaturated fats like olive oil, which is a single double bond, or saturated fat like, say, butter, animal fats, typically saturated, you know, where you have no double bonds. And let me start with this. I don't think seed oils are innocuous from the perspective that in the last few decades, added oils are one of the biggest sources of increased energy in the American diet. And so I just want to set the stage appropriately as well, talking about levers. People will say, well, it can't just be the calories. Let me give you the data on calories right now. So if we— people will say, no, it's 2,400 calories have actually gone down in the American diet. I've heard this argument. They're looking at self-reported data from people, which puts it at like 2,400, 2,500 calories a day for Americans. The more accurate way to look at it is you look at the food production, you look at food waste, and you look at food availability, and you can calculate approximately how many calories per capita people are consuming. Okay, that is objective data. That's not, well, yesterday I think I had— Like, I don't even remember what I had to eat yesterday. Like, I mean, I can look at my app and I know, but if you ask me to recall it offhand, like, God, I don't really know. That data is over 3,500 calories a day on average per person, and the average person gets less than 20 minutes of physical activity per day. So yeah, I, I think like a big chunk of it is energy toxicity.

Seed oils can contribute to that for sure, because even right down to like, hey, you have a salad, what does it take for a chef just to, you know, put more oil on it? Or, you know, if you've ever had a dish, you know, I can approximately guesstimate like how much rice is on there, but how are you going to know how much oil somebody put in? Like, I mean, I guess it tastes a little bit slimier in your mouth, but good luck quantifying that, right? And then I think also seed oils are probably a proxy for poor overall diet quality because they are in a lot of processed foods. So the question to me, there's 2 questions. Practically, are they contributing to the health crisis? Yes. But is it for the reason that the really anti-seed oil people claim?

And what's interesting about this anti-seed oil movement is I've noticed it's kind of popped up out of the low-carb carnivore sphere. And I've seen this progression over the years, which at first, the kind of the low-carb hardcore keto folks were carbs are bad, just blanket carbs are bad. And then over time, that kind of shifted to, well, we think it's refined sugar is what's, you know, bad insulin. And then, I mean, we've had so many randomized controlled trials now and meta-analyses that kind of show that like sugar isn't good for you.

But if you're equating energy, like, I mean, I have several meta-analyses to show that it doesn't affect inflammatory markers, doesn't affect blood glucose metabolism, as long as you're getting in the same total calories per day compared to other diets and substituting out different carbohydrate sources. So then it shifted to And I think it coincides with— there's been a lot of low-carb people who also push for saturated fat to be healthy. Because I, again, I think this is like confirmation bias. We like animal protein. We want saturated fat to be good for us because then we can justify more animal protein.

And hey, listen, I always find it funny when people accuse me of bias on this because my research was funded by the National Dairy Council, the Egg Nutrition Center, and the National Cattlemen's Beef Association. There is nobody with a stronger bias towards animal protein than me, right? And I can remember when I did a debate with a carnivore person one time, I said, never in a million years I think I'd be on a podcast defending the virtues of plants. So I'm not saying that there isn't some benefits to animal protein. Everything's trade-offs. But if we look at the literature—if you say seed oils are uniquely deleterious to health, then you have to say saturated fat is uniquely deleterious to health.

Because for every level of evidence for seed oils, there is stronger evidence for saturated fat to be deleterious on health. So mechanistically, we know saturated fat raises LDL cholesterol. We know LDL cholesterol penetrates the endothelium. We know LDL cholesterol is a causative risk factor for cardiovascular disease. Now we can argue about particle size and all that kind of stuff, but we know regardless of particle size, LDL can penetrate the endothelium and cause damage. Okay, mechanism, right? And then people say, well, inflammation. Okay, well, if we look at the studies where they just have people eat more polyunsaturated fats, sometimes you see an increase in inflammation, sometimes you don't.

But if we look at the studies where they're substituting polyunsaturated fats in place of saturated fats, we see neutral or positive effects on inflammatory markers, blood glucose regulation, liver fat. In fact, one of the things I tell people is if you're worried about liver fat increase from fructose, you better be worried about saturated fat because they compared them straight up equating calories overfeeding fructose versus saturated fat. Saturated fat increased liver fat 70% more than fructose in a randomized controlled trial. So again, all right, you want to make the argument that seed oils are bad for you, you have to make the argument that saturated fat is bad for you too.

And usually it's kind of the opposite where they're trying to push that, you know, polyunsaturated fats are what's causing a lot of our health problems, when in reality at every level of evidence, whether it's animal mechanistic, human randomized controlled trials, or epidemiological, looking at polyunsaturated substituted for— or saturated substituted for polyunsaturated, it's either neutral or positive. And so again, with the seed oil thing, if you were looking at just, yes, it adds calories, but is it independently increasing inflammation? Like if we're talking about actual polyunsaturated fats, like not trans fats, I mean, if you're overeating it, sure, but if you're replacing saturated fat with that, the evidence suggests it's neutral or positive.

And so you're— they're talking about a mechanism. Well, those double bonds can oxidize and there can be XYZ. Okay, but what happens when you just feed it to people? And then you see— now some people have said, and we talked about this, like heating and reheating, it's probably not even like one-time heating, it's probably like multiple times heating, depends on the smoke point, all that kind of stuff. Um, but again, that's confounded by the fact that, okay, if you're heating and reheating, you're frying stuff, and fried food is a proxy for really poor diet quality. So again, is it the seed oils that they're frying it in, or is it the fact that these people just eat really poorly overall in these cohort studies who are eating a lot of fried foods? Certainly in the cohort studies. So the seed oils, so far the randomized controlled trial evidence doesn't suggest it increases cardiovascular disease, doesn't suggest it increases inflammatory biomarkers, at least in the randomized trials.

Dr. Rhonda Patrick: Yeah, like CRP or bile acids.

Dr. Layne Norton: CRP and some of the— yeah.

Dr. Rhonda Patrick: Now the heated versus the nonheated, and this is where I kind of think seed oils can be bad, and that it does have to do with what you said about cohort evidence is true, right? Because you're right, you can't know, are they just frying all this terrible food?

Dr. Layne Norton: There are too many confounders.

Dr. Rhonda Patrick: Right. There are very few, three or four, studies that have interestingly compared heating some seed oils, a lot of times it's safflower oil.

Dr. Layne Norton: Yeah.

Dr. Rhonda Patrick: They'll heat it or even do repeated heating, like once they did 20 and then did not and then made muffins, the same muffins with either the— I thought it was a great study, you know, the 20 times heated oil versus just the cool, like not heated oil. And the heated oils did increase inflammatory markers and they increased oxidized LDL. And like I said, too few studies really comparing just non-heated with heated.

Dr. Layne Norton: Yeah.

Dr. Rhonda Patrick: Because essentially, a lot of those randomized controlled trials showing no effect on inflammation with seed oils, they were giving them pills that were— they weren't cooking the seed oil, right? They're just putting it in the pill.

So I do think there's a strong possibility based on the very limited evidence so far that heated seed oils might cause more inflammation compared to consuming them Certainly in whole foods, but even just like putting it on a salad or— I don't know. What are your thoughts?

Dr. Layne Norton: It's kind of like if we look at the priority of what's important, that's some of the last stuff I'm worried about just because I'm like, again, most people are eating over 3,500 calories a day, doing less than 20 minutes of physical activity. Okay, let's get that under control first. And if you happen to be eating some seed oils while you're getting your calories down to, I don't know, 2,500 a day, not really that worried about it, right?

But, you know, do I think it's a good idea to eat a lot of highly processed foods that have had seed oils that are heated and reheated? No, I don't think it's a good idea. But I don't—

Dr. Rhonda Patrick: We have options too, right? What about avocado oil or olive oil? Do you think that maybe just getting a couple of those options?

Dr. Layne Norton: Yeah. I mean, like, you know, there was one really big cohort meta-analyses that was done that kind of showed that monounsaturated didn't have as big of an effect as polyunsaturates as decreasing the risk of cardiovascular disease. That monounsaturated was still positive and saturated was negative, but polyunsaturates was kind of better in a dose-response. But I mean, I think for the most part, if you're worried, use olive oil, use avocado.

Dr. Rhonda Patrick: What about the polyphenols in olive oil? There's some studies showing, like randomized controlled trials showing a beneficial effect just from on cardiovascular disease with olive oil.

Dr. Layne Norton: Yeah, I think olive oil specifically, there's, there's some evidence that like it may have some unique benefits for cardiovascular disease and whatnot, um, and like metabolic health overall. So, but again, I kind of look at that and go, okay, well, it still has one double bond that can be oxidized. That can be, you know, based on your mechanism for polyunsaturates, right? Like, shouldn't olive oil still be worse than saturated as well? And you can't like They never make that argument, or at least not that I've seen. So yeah, I mean, I think, again, we agree.

I might agree for a different reason in that I don't know if I've seen enough to really— I think if you're heating and reheating, yes. Like, once you get to the point where you're oxidizing those double bonds, I mean, now you're— who knows what's happening downstream of that? But I think it's probably, you know, people who are eating a lot of heated and reheated oils are just eating really crappy foods overall. You know, like, I'm not really worried about somebody who's, you know, they spray their pan with canola oil and cook some eggs on it. You know, like, I just— I'm not worried about that. It's, you know, the person eating fries that have been refried in the same oil over the course of time.

But then again, it's like All right, well, is it the oil or is it overall they're having a really poor quality overall diet? So I, I think for me, yes, I hold very much open the possibility that there could be some deleterious effects. But I think for most people, it's one of the reasons I say have guidelines, don't have rules, right? Because if you say things like, I don't eat seed oils, well, as a guideline, that might be okay because you're probably avoiding a lot of like hyper ultra-processed hyperpalatable foods, fried foods. But when you're like, you know, cooking in a bunch of butter instead of like canola oil or olive oil, or, well, I guess not olive oil, but, um, like you're kind of missing the point.