Butter vs Plant Oils: What 200,000 People's Data Actually Shows | Andrea Glenn | EP#416

Added: 2026-05-10

[00:00:00]You sent me a few other nutrition studies that have come out in like the last year or so. I believe you're not you weren't a direct author on these, but there's some overlap with your group and you're familiar with them and and I think they speak to foods that people are consuming every day. And so our audience will be interested in in kind of what these studies show us. Maybe we can start with the the one that looked at butter versus plant-based oils. Yeah, so this one came out in JAMA Internal Medicine last year.

[00:00:32]Um and I think it's uh probably a pretty relevant paper in our hate on seed oil era. Um they looked at butter and plant oils and they specifically looked at safflower, soybean, corn, canola, and olive oil. Um so they created like a variable that had all of these foods together. Um and then they looked at them individually.

[00:00:54]And this is also in the Harvard cohorts, so the same like 200,000 healthcare professionals, 30 years of follow-up, and this one they're looking at mortality.

[00:01:04]Um so what they found was that those who were consuming the highest butter intake had a 15% higher risk of total mortality compared to lowest. And that those who had the highest intake of plant-based oils had a 16% lower risk of total mortality compared to those consuming less plant oils.

[00:01:26]Um so maybe different than what some people might expect given some of the advice that's currently out there. When they saw that most of this was related to soybean, canola, and olive oil. This is a great example of a study where immediate pushback will be this must be industry funded. So this must be funded by canola or soy or safflower uh or olive oil um and or healthy user bias. Right.

[00:01:57]Yes, so they did do all these adjustments that I talked about earlier and I believe they did lots of sensitivity analysis as well to try and see what happens with that and I don't know about the funding, but I'm pretty sure it's not canola oil. Right.

[00:02:12]>> [laughter] >> I mean I looked at the funding and it didn't look like it was industry funded.

[00:02:15]>> Yeah, it's I think it's probably just students working on this data.

[00:02:19]Um but it's a great question and I think um you know, they did do all the same adjustments and they still saw higher risk of mortality with butter compared to plant-based oils.

[00:02:31]>> And that was total mortality or was there was it disease specific mortality?

[00:02:38]It's a great question.

[00:02:41]I think it was Yes, they did look at cancer and cardiovascular disease mortality as well. Right. And I believe they saw that plant-based oils were associated with lower risk of cardiovascular disease um mortality and some of them were also related to cancer mortality. Higher intake of butter was associated with higher cancer mortality. So with with that in mind, why do you think that the the butter is back kind of rhetoric >> [snorts] >> it's kind of picked up steam again. Yes.

[00:03:14]>> Particularly I I don't spend a lot of time on TikTok and Instagram, but people send me this stuff and there's people that are putting big plates of butter and you see this? I have, yes.

[00:03:24]>> Yeah, it's a trend. Yeah. It's It seems ridiculous to me, but anyway, for whatever reason that has become a kind of popular video piece of content to do.

[00:03:34]Yeah.

[00:03:35]So what's behind that as a and how do you feel about that as a as a registered dietitian and nutrition scientist? I think it might have to do with like natural foods kind of people trying to avoid processed foods or foods that can't pronounce.

[00:03:52]Um I think that's where a lot of it's coming from cuz butter is natural.

[00:03:56]Um I assume anyway. I I also don't spend that much time on social media. Um but I assume that's where a lot of it's coming from. It's more natural. Which is then a kind of uh a presumption that what's natural is best. Yeah, exactly, which is not always true. And we also obviously have data to support a lot of that. Um but I think as a dietitian, it just seems kind of silly.

[00:04:21]So what do you cook with at home? And what would you tell your family to cook with? Oh yeah, I cook with olive oil mainly. Um sometimes canola oil, but mostly olive oil. My dad has high cholesterol, so I got him to cut back on the butter and his cholesterol went down. Begrudgingly or?

[00:04:38]Uh no, he was open to it. Um he ended up using like kind of the like olive oil margarine spreads cuz he does like that type of spread on his bread. But it helped, his cholesterol went down. So yeah. Okay. Is he on the viscous foods as well? Not as much.

[00:04:54]>> [laughter] >> That's all right.

[00:04:57]>> convinced him to do any oats.

[00:04:59]>> Or barley. Give him time. Adherence will go up in time.

[00:05:02]>> [laughter] >> Exactly.

[00:05:03]>> Right. Um that's a good first step.

[00:05:06]Okay. Proud proud of your dad. So that's that was that study. Anything else on that one before we move to the next one?

[00:05:12]Um no, we can go to the next one.

[00:05:14]So let's go to the the study that looked at plant versus animal mono unsaturated fats and risk of type 2 diabetes. Yes. So this is in the same cohort again, different outcome, but still looking at fatty acids. Um and in this one, it's mono unsaturated fatty acids. And what they did in this paper is they looked at total mono unsaturated fatty acids overall.

[00:05:42]And then they looked at the MUFAs that came from animals and the MUFAs that came from plants. So, they kind of split it up and looked at the association with type 2 diabetes.

[00:05:52]And they found that overall, MUFAs was associated with an increased risk, but that was totally explained by MUFAs from animal foods.

[00:06:01]Whereas, the plant-based MUFAs was associated with a lower risk of type 2 diabetes. Um and I just think this is kind of really interesting because it highlights more food source than overall macronutrients, which I think a lot of this data is kind of highlighting that we need to focus more on the type of food that we're eating as well as the replacement behind it. Which gets lost if you just tell people to eat low fat or high fat.

[00:06:28]>> Exactly. Like, what does that mean? What should I be eating? What should I cut out? Yeah. So, how do you think about this at a mechanism level?

[00:06:36]If someone's thinking, "Okay, so monounsaturated fats from plant foods associated with lower risk of diabetes, but let's take oleic acid, which is like the the most prominent monounsaturated fat in olive oil.

[00:06:49]Uh and they're thinking, "Look, at a molecular level, oleic acid is oleic acid, whether it comes from a steak or olive oil."

[00:06:57]With that in mind, like, what what do you think explains the divergent associations that that this paper found between the source of those? Yeah, I think a lot of it is displacement as well. Um so, we're getting rid of some of the saturated fat that comes along with that steak. Um and there's some research showing that saturated fat might increase insulin resistance and that could relate to type 2 diabetes.

[00:07:21]Um so, I think that's a big part, displacement. You're not getting the parts of the animal along with those MUFAs, and that could be also um some of the protein or the heme iron that comes along with those products.

[00:07:35]Um and then in terms of >> [snorts] >> if we're using oleic acid in olive oil, there could be some some like the polyphenols in those products as well um or the fiber and some of the um the plant foods. It's kind of like the overall package.

[00:07:49]>> So, those those things that you just mentioned there, so saturated fat, heme iron, fiber, polyphenols, all of these kind of come along for the ride with the monounsaturated fat, depending on where you're getting it from.

[00:08:03]And would you say, based on your understanding of of how nutrition affects diabetes risk, that outside of calories, cuz obviously calories make a big difference when it comes to risk of diabetes, right? So, if you kind of park put calories to the side, calories are equal, those nutritional factors can inherently or independently affect someone's risk of diabetes? So, in the discussion, they mentioned um some of these parameters we already talked about as well as replacement of carbohydrates as a potential role for the plant-based MUFAs lowering risk of diabetes. And the third paper, which you sent across, also from from Frank Hu. He's been busy.

[00:08:48]He's been very busy. He's publishing a lot of papers. He does publish a lot.

[00:08:52]>> get Frank on the show one day. Maybe you can you can put a good word in for me.

[00:08:55]>> Yeah, absolutely.

[00:08:56]He and his colleagues published another paper on on type 2 diabetes.

[00:09:02]And I found this one really interesting and I thought the low-carb ketogenic community would as well and perhaps share it, but I didn't see it.

[00:09:10]It wasn't shared that widely.

[00:09:12]>> [snorts] >> And it was looking at different low-carb diets and the risk of type 2 diabetes. Yeah, so they actually looked at five different scoring systems.

[00:09:23]So, a lot of data here.

[00:09:24]Um and this is again in the same three Harvard cohorts.

[00:09:29]Um they did an overall low-carb diet, so that would focus more on total protein and fat.

[00:09:36]They did an animal-based low-carb diet, so that's more emphasizing animal protein and fat.

[00:09:43]They did an unhealthy low-carb diet, which was based on the animal-based one, but it kind of deprioritized healthier carbohydrates, like whole grains.

[00:09:54]They did a vegetable-based one that was prioritizing um plant protein and fat, and then the healthy low-carb diet prioritized healthy plant protein and fat, and then they also deprioritized more refined grains.

[00:10:10]Um so, there's a lot going on there.

[00:10:11]>> That's interesting though, because often when looking at like an animal-based low-carb diet, the first thing that people say is, "Well, that was a that was a low-quality. That was an unhealthy low-carb diet." So, in this analysis, they actually separated them out, it looks like. I think so, yep. Yeah. Yeah, they prioritized the grains a bit more.

[00:10:33]Um And really interesting what they found, so they compared quintiles, so like highest to lowest adherence to these types of dietary patterns.

[00:10:42]The overall low-carb diet was associated with a 31% increased risk of type 2 diabetes.

[00:10:48]That went up to 39% for the animal-based, and then that went up to 44% for the animal-based plus deprioritizing whole grains.

[00:10:58]And then they saw the opposite for the vegetable-based low-carb diet. Um so, they saw a 6% reduction, and then a 16% reduction when they combined it with um what they call the healthy low-carb diet, where they deprioritized the refined grains. So, essentially whether or not a low-carbohydrate diet was increasing or decreasing risk of type 2 diabetes depended on the quality.

[00:11:25]Yes.

[00:11:26]>> And when it when it featured more animal protein or more unhealthy carbohydrates for the carbohydrates that it did include, it was increasing risk, whereas when it included more fiber-rich foods and less refined grains, Yep. and presumably if it's less animal-based and had more plant protein, then it was associated with the greatest reduction in risk of type 2 diabetes.

[00:11:51]Yep, which is really interesting to highlight. Um And I think importantly, the percent energy was like 30 to 40% in the low-carb diets. So, some people There'd be some pushback on that.

[00:12:05]>> Yeah, They'd say that's not ketogenic.

[00:12:07]Exactly.

[00:12:07]>> know what? I would say granted.

[00:12:10]Also, I'd say not many people can adhere to a diet lower than 30% of calories from carbohydrates for very long. Yeah.

[00:12:17]So, you could go and run that analysis.

[00:12:19]There probably wouldn't be many subjects in that cohort that were doing [laughter] that. And that's reflective of of real life. Yeah, exactly.

[00:12:26]Especially like maybe they'll do it for a couple years, but this is usually like a cumulative average and they do intake over time.

[00:12:33]I doubt there's anybody who is following a ketogenic diet for is it 30 years in these papers. But the take-home point is if you're someone that is restricting carbohydrates to a degree, the foods that you are eating matters.

[00:12:50]Yes. All right, you can do it in a way that's less healthy or more healthy.

[00:12:55]Yep.

[00:12:55]And I think that's kind of the big take-home from a lot of these papers is that it's not just the macronutrients that matter, it's the food sources that matter. Right. So, in that circumstance, the healthy low-carb diet would have had more plant protein, like the foods we've been talking about. Yep. Fatty fish probably, cuz they tend to have a healthier fat profile than than other meats. And then whole grains and lots of fruits and vegetables rich in fiber. Yep, exactly.

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