The seed oil debate: are they uniquely harmful relative to other dietary fats? | Layne Norton, Ph.D.

**Peter Attia** (0:11)
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My guest this week is Layne Norton. Layne is a nutrition scientist, an accomplished power athlete and a very evidence-based thinker in the space of diet and metabolic health. While Layne has been on the podcast many times, today's episode is a little bit different from the usual podcast dynamic. Now, originally, this was supposed to be our first in a series that we've been toying with, which is a debate episode. I've talked about these a little bit on other podcasts, but the long and short of it is, I wanted to do a debate that was going to be incredibly rigorous. In fairness, I've never really seen a podcast debate that was anything other than nonsense, if I'm being blunt. The reason is the format is basically impossible because people can make up anything they want, they can cite anything they want out of context, and no human has the capacity to know the entire body of literature upfront, and therefore, it's very difficult to counter claims, regardless of whatever the topic of discussion is. I've just never found this appealing. So over the past year, we've been noodling this idea of, well, what if we ran a debate like a court case? Of course, in a court case, everybody has to present their evidence upfront during a process called discovery. That allows both sides to view the evidence of the opposing arguments along with their own arguments in equal time. That way, there's no ambiguity about what's being presented. We came up with an idea, which was we were going to start with this first topic, which is to be the seed oil debate, which I'll clarify a little bit more in a moment. The idea was we'll take two very thoughtful individuals who have opposing views, and we did just that. So Layne was on the side of the argument, which was that seed oils are not harmful. We had an individual who took the opposite point of view on that. The idea was that Layne and this other individual would share all of the information that they planned to present with our team and with each other, and that I would serve really here as a moderator of this discussion, and my research team would serve as the fact checkers, and that you as the public would basically serve as the jury to my judge. However, the individual on the other side of this argument, for reasons that I'm not entirely clear, decided that they just didn't want to do this, and we felt that it was still a worthwhile topic to explore, and while the format of today's podcast is, in my view, not as potentially interesting as it would have been had we done the original debate, we still think that it brought a lot of value. So what I did was I kind of attempted to steel man the argument against seed oils, and therefore allow Layne to represent the pro-seed oil position for why seed oils may or may not be harmful when consumed in isocaloric quantities relative to other fatty acids. That really is kind of the jugular question here, which is I don't think anybody would dispute that consuming excess anything is harmful. So consuming excess calories in the form of seed oils versus monounsaturated fats versus polyunsaturated fats versus carbohydrates, probably not many people are going to debate the downside of that. But what we were really trying to understand is, is there something that under even isocaloric conditions would make seed oils particularly metabolically harmful? So in this episode, we're going to discuss the role of bias, evidence evaluation and scientific interpretation is a lead in to this, the historical randomized controlled trials that shape the seed oil conversation, the mechanistic biology of LDL, oxidation and atherosclerosis, which is central to this argument or at least one of the arguments, the methods of oil processing and the chemistry behind modern seed oils, how evolutionary and ancestral arguments fit into these nutritional debates, the relationship between seed oils, ultra processed foods and modern dietary patterns, the broader lifestyle factors that influence cardiometabolic health, and then ultimately practical considerations around dietary fats, cooking oils and real world food choices. In the end, I think we salvaged a lot of hard work that had gone into the preparation for the debate over the course of a year. Ultimately, I think you're going to find a lot of value in this. Without further delay, please enjoy my conversation with Layne Norton.