19
votes
What is the truth about risks and benefits of seed oils?
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- Title
- RFK Jr says they are poisoning us, influencers call them unnatural - but what is the truth about seed oils?
- Published
- Mar 29 2025
- Word count
- 1166 words
https://youtu.be/efTBLsv4yYs?si=DwLH_N9GhM5q5aoM
I found this podcast by Adam Ragusea to be a very good run down of what the science says ( or at least what it said 2 years ago). While there are a few serious scientists arguing that seed oils can be harmful, the vast majority of scientists studying this kind of thing believe that there is insufficient evidence that seed oils are harmful and significant evidence that they are much less harmful than animal fats.
But his point at the end is what i find the most compelling. These scientists are the only ones who can really have any sort of valid opinion. The rest of us, and that especially includes every tiktok health influencer, lack the decades of experience required to truly understand the enormously complex systems in human nutrition and should really just stick to admitting that we don't know and to trusting the current consensus. And at the moment the overwhelming consensus is that seed oils are not harmful and overall much healthier to consume than animal fats. But if you can afford to stick to olive and avocado oils, that's probably the best choice.
I hate that argument. Food is cultural. Many dishes that are regional or national staples wouldn’t qualify as healthy under this paradigm. Now, I agree that nutritional scientists should have a seat at the table in terms of food policy. But if you don’t bring in other stakeholders, these “ideal recommendations” would not stick around for very long.
I think it's more in the "determine what's harmful" than " telling you specifically what you should eat.". There are tons of influencers who walk around grocery stores yelling at viewers for daring to eat, say, seed oils or artificial sweetener and then will hawk products that contain... You guessed it, seed oils and artificial sweeteners.
That's where people should be listening to experts.
I wholeheartedly agree.
I recently came across a blog post that does a good job at explaining why it's not an exact science yet: https://dynomight.net/seed-oil/.
The article suggests that there is no strong scientific consensus that seed oils are inherently harmful, but there are plausible concerns. While some studies link seed oils to negative health outcomes, others show neutral or even beneficial effects. Mainstream nutrition generally considers polyunsaturated fats, including those in seed oils, to be healthier than saturated fats. However, skeptics argue that factors like oxidation, inflammation, and processing methods could contribute to health issues. The lack of definitive evidence means the debate is ongoing, with both sides presenting reasonable arguments but no clear resolution.
Correct me if I am wrong. I'm no scientist. My understanding, of why seed oils are bad, is the refining process which uses a lot of heat. Short chain fatty acids are prone to oxidation. By consuming seed oils you are basically dumping free radicals into your system. These oxidized fats are then used by your body to make crappy cell walls which are weaker and more prone to failure. Fat is essential for many metabolic processes and you are basically starting with poor source material.
I feel like you might be responding to the title without having read the article? Because the article very much goes into detail about all of this.
Bruh, I made that comment because the article doesnt touch on the topic.
The article does touch on the topic though. Both directly and indirectly. For example, it does mention that cold pressed oils are less common, but also says that solvents are more commonly used (implicitly saying that heat also isn't used). It also specifically states that anything potentially harmful will be removed in the process.
You mention short chain fatty acids, seed oils primarily contain long chain fatty acids (like linoleic acid mentioned in the article), not short chain fatty acids.
The article doesn't directly address your oxidation claims, though see also my previous point. It does challenge the broader narrative that seed oils are harmful. In fact the research cited in the article found that replacing butter with plant-based oils was associated with a 17% reduction in risk of death from all causes.
As far as "crappy cell walls" go, it is stated that linoleic acid (the primary fatty acid in seed oils) is "an essential nutrient" that is important for immune function and platelet function.
Everything in the article challenges your claim for "poor source material" and actually suggests that these oils may have health benefits. And that is what prompted me to wonder if you had even read the article.
I believe your premise is not quite right. As far as I know seed oils aren't inherently bad for you. There's simply a correlation between how they're often used for cooking and adverse health effects of those cooking methods. Any oil you repeatedly heat and fry stuff in becomes worse and worse for you due to changes occuring when heating the oil. Seed oils per se don't have that problem if they're used differently, and other oils suffer the same fate when used that way.
Here's a two minute clip from a SciShow video summarizing that point quite nicely (starting at 6:44): https://www.youtube.com/watch?v=Ikev3XcqAJM&t=404
Do you have some (good) data? I appreciate the article because it takes the things that sound like they could be true and provide expert opinions on the research.
That sounds wrong. What's the justification for that claim ?
The scientists agree with you.
That channel/site (NutritionFacts.org) and its creator (Michael Greger, MD) don't seem to be entirely unbiased or wholly trustworthy sources of information. They're a whole-food, plant-based, vegan diet advocate with an apparently somewhat questionable history of making unsubstantiated health claims and cherry picking data. See:
https://sciencebasedmedicine.org/death-as-a-foodborne-illness-curable-by-veganism/
https://www.redpenreviews.org/reviews/how-not-to-diet/#scroll-scientific-accuracy
https://www.redpenreviews.org/reviews/how-not-to-diet/#scroll-unusual-claim
https://www.healthline.com/nutrition/how-not-to-die-review
p.s. I have nothing against vegan diets, per se. But there are unfortunately a lot of advocates for veganism that take their health claims a little too far, and Dr Greger appears to be one of them.
LIterally every doctor that talks about vegan diets in a positive light gets this kind of pushback. Dr. Greger gets the worst of it because he is one of the most visible advocates for whole food plant based diets. You yourself are doing it right now: a quick ctrl-f search didn't have any of them use the word "unsubstantiated" - though to be fair, I am not in a place to be reading them fully critical at the moment so I could have missed it. In any case, Greger is often thought of as less trustworthy because there is a social thirst for disbelief in his message.
I find this to be a really bad thing. Not only because I personally follow a whole food plant based diet, but because I think that the distrust is so much less deserved than the people who are promoting diets that we know are not healthy for you, like carnivore, varieties of paleo, atkins, keto, etc. When talking about the potential negative effects of his diet advice, the worst criticism I have ever seen about the potential side-effects are that you could have are vitamin deficiency - most commonly for B12, which is strange to me because B12 is one of the things that he says to feel free to get from supplements.
Talking about dieting is going into lifestyle medicine, which is the single most complex medical topic because it's holistic in nature. There is no way to publish books as long and detailed as How Not to Die etc. without error. Since it is a holistic view, it's essentially impossible to avoid "cherry-picking". It's also important to keep in mind that his videos and books are meant for mass communication and thus are not meant to be put to the same standards as his academic writings.
That being said, his videos are a whole lot less researched than his books, so I wouldn't take them super seriously either. They quote studies, but I think it's important to realize that the conclusions are essentially opinions, and some of them you might even categorize as hot takes. But to Greger's credits, looking through his website I have seen corrections, so he does update his stuff and updates his opinions as the science advances. When evaluating him as a health influencer rather than a doctor, I'd actually say he's at or near the top tier.
It's almost like "unsubstantiated" can be expressed in multiple different ways. How about RTFAs I linked to before you jump down my throat next time. At least read the first one, which is the most comprehensive and damning criticism of one of his videos. But the other two articles focused on the issues present in two of his books also don't paint the most flattering picture of him and his claims either.
Or perhaps he is thought of as less trustworthy because he keeps making bold claims like “a plant-based diet of fruits, vegetables, whole grains, legumes, no meat, reverses heart disease, completely prevents deaths from heart disease, and slows the progression of cancer” that lack evidence to support them?
I’m not jumping down your throat and I’m sorrry if I made that impression on you. I have read the first article before and I also pointed out that his videos are relatively low quality compared to his other works which have extensive citation.
The other two links are critical reviews and to properly evaluate their counterclaims I would have to do extensive research in a field I have relatively little knowledge of. Frankly it’s not fair to expect me to put that much labor into it.
You put that phrase in quotation marks but to my knowledge he has never made such a claim. He has made simelar claims, but they have significantly more reasoning, complications , and nuances associated with them, and he typically cites studies. I’ve seen him do it even in an informal interview before.
If you don’t agree with what he said in that video that is fine. But right now it seems more like you’re trying to do a character assasination.
It's a word for word quote of him from his video lecture, the one the first article I linked to is criticizing.
p.s. BTW, just because I am critical of someone and skeptical of some of that person's claims doesn't invalid absolutely all their advice. Eating a balanced, whole food, plant based diet is undeniably far healthier than the vast majority of other diets out there. And if that was all Dr Greger claimed then I would have no problems with him.
And I also truly commend you for your own whole food plant based diet. That takes an amazing level of commitment and discipline! I myself am an on-again/off-again pescatarian, albeit not especially strict (cured meat is my kryptonite! and I occasionally still eat chicken/turkey). And at some point I would like to go strict pescatarian, but fully admit I am simply not disciplined enough for pure vegetarianism/veganism despite the health benefits. So I am genuinely not against the idea of vegetarianism/veganism, or even promotion of those diets. I do, however, have a serious issue with people treating them like a panacea and making claims to that effect.
This is the actual quote from the transcript of the video in questions, if anyone wants to find it and read it. Just different enough to make searching not 100% accurate but the meaning was the same.
Thanks for that. I actually took the quote from the YouTube transcript, BTW... so that's where the slight difference in wording came from. Like you said though, the meaning is the same regardless.
I just got back from a city trek, and found that. The section @cfabbro is quoting is in quotes itself because it's a direct quote from another academic paper. I found a version of it here. That excerpt also has a note that points to almost a full page of notes with citations. So it appears there's actually a decent amount of research to back up those claims. Just to make sure that the article wasn't some crackpot thing I put it into Google Scholar and it looks like it's cited 41 times.
I know the claims are strong, but nutrition and diet is continuously coming up with paradigm shifts like this. Just in the past 20-30 years, we've seen a lot of papers written about health effects of things like the gut microbiome and ultraprocessed foodstuff. If we go back further we can see them flip-flopping on things like dietary cholesterol and the replacement of saturated fats with transsaturated fats. Years ago red meat used to be symbols of health and wealth, but now we know it causes cancer and heart issues. Greger's opinions may not be mainstream, but they aren't exactly crackpot either.
Once again, I really do recommend reading (or rereading, as the case may be) the first article I linked to... she goes through each of Greger's claims in that lecture one by one. E.g. For that particular claim of his about heart disease and cancer:
So Greger may not be a total quack, and I'm sure lots of his advice is perfectly sound. But at least some his more bold claims about the health benefits of veganism clearly don't hold up to scrutiny, and he also appears to have a habit of misrepresenting/exaggerating (or simply misunderstanding) the actual findings of certain studies. Hence my original comment about him and his site not being a wholly trustworthy source of information.
Nobody will ever make completely accurate statements all of the time. The author of the article that you want me to re-read rather famously endorsed the anti-trans pseudoscience book Irreversable Damage on that very site, and I don't see any reference to her recanting it before her death. I don't think that makes the rest of her work completely invalid. Why should we hold Greger to a higher standard? Surely telling people to avoid processed foods and animal products does significantly less damage to society.
Now that I look at it, I actually see a problem with your excerpt. The section on Cancer criticizes the article that he cites rather than Greger's work itself. Looking further into it, Hall also seems to be misrepresenting what it's trying to say. Here's the quote from the article (emphasis mine):
The article at hand was also not cited to support the idea that cancer was preventable, it was brought up for the main idea of it - that there are conflicts of interest in the making of the Dietary Guidelines for Americans.
It should also be mentioned that the video is over a dozen years old and science has advanced since then. I'm not smart enough to really follow everything that's happening but chatgpt seems to think that people are still building on Essylstein's work.
Skepticism can be a good thing. It can protect you from being taken advantage of. But if you're too skeptical it can keep you from the actual truth and make you stubbornly unable to understand viewpoints other than your own.
Sure, not everyone is correct all the time... and I try not to hold people to that absurd of a standard. But when people like Dr Greger make claims like "X diet completely prevents deaths from heart disease" even if they're just regurgitating it from another questionable source, I think they absolutely deserve to have their motivations and credibility questioned when they're presenting it as incontrovertible truth, regardless of how long ago they made such a statement. And it's not overzealous skepticism to do that when the claim is that wildly unbelievable, on its face, it's perfectly healthy skepticism, IMO.
Perhaps he has wised up since then, and doesn't make absurd health claims about veganism anymore, but based on the book reviews on his books which were published in 2015 and 2019, it seems he still doesn't do a very good job of accurately relaying the findings of studies he cites. E.g.
So, frankly, I still don't see any reason to trust him.
I have been watching this conversation between you and @Akir unfold with some curiosity/slight bafflement. To be frank, you both seem to be talking very neatly past each other while completely ignoring the initial context. You've shifted from discussing adverse health effects of refined seed oils to debating the credibility of one vegan diet promoter.
I'm puzzled by the hyper-focus on one person from both of you. When it comes to nutrition, there is no single authority who can speak with absolute certainty. Even more concerning, the conversation is full of appeals to authority, ad hominem attacks, and "tu quoque" responses, making it difficult to extract any useful information about the original topic.
I was about to type out a much longer response examining each point, but I'm not sure how helpful that would be. At this point, this has thoroughly devolved into an internet slap fight. A well-articulated one, but a slap fight nevertheless.
Fair criticism. I doubt either of us were going to change our opinions on Dr Greger, so it was kind of a pointless conversation that ended up getting hyper fixated on him. But that's how conversations sometimes go. ¯\_(ツ)_/¯
However, I personally think accusing anyone of 'ad hominem' when they're criticizing someone speaking with authority and making rather bold claims, is a bit of an inappropriate deflection though. Credibility matters when it comes to someone sharing their so-called "expert" advice. And if that someone has a history of misrepresenting facts, lying by omission, and cherry-picking studies to back up those bold claims, then that deserves to be pointed out regardless of if it's technically an 'ad hominem' to do so, IMO.
As I said, I don't feel like doing a point by point response to this entire discussion. My comment was aimed at the both of you hence me pinging Akir as well. Both of you threw in the fair share of fallacies, and I'll leave it to you to reflect on that. Or not, I am not your boss just merely observing.
They do no such thing. For starters, the video you linked is about the presence of glycidol in refined oils (any refined oil) which has nothing to do with the idea of lipid oxidation, free radicals and cell membrane degradation.
Even in this context there is no "scientists agree" as it is a much more complex subject. Since the video is on the short side I attempted to look into it a bit more. To be clear, it seems that glycidol as a compound is generally agreed on to be harmful. It also does seem to be present in refined oils. However, here things do become a lot more complex. Complex to the point that you can't just say refined oils bad unrefined oils good.
The biggest issue with glycidol comes seems to come down to the quantity you ingest. When frying foods the amount of glycidol ingested is higher. For people who have a large amount of fried foods in their diet this can result in various higher risks in regard to cancer (prostate cancer). At the same time, frying in unrefined oils brings other risks as these release other compounds when frying foods.
The risks seem to go down when we start talking about baking instead of frying. Simply because there is less contact between the oils and the food and because temperatures are lower.
So from everything I gather:
Extra disclaimer: I am not a scientist or food expert
Which is why I made sure to not put anything in definitive terms. As a lot of things in this world this stuff is complex as hell. Which is not fun for us as consumers, but trying to reducing them to simple solved issues is akin to sticking your head in the sand and not productive either.
It’s a bummer that as a whole, frying things isn’t the most healthy. It’s quick and easy way to cook foods and make them tasty without dirtying a lot of dishes. Fresh veggies are good and all but sometimes you gotta add some fat and caramelization.
I think a key here is that watching your temperature (so you don't smoke your oil) and not using more oil than is needed to keep your food from sticking are key. Moderation and all that. I suspect that frying veggies and having a diet that's high in veggies, fiber, and protein while being low in starch, fat, and sugar is probably putting any risks from frying in a much lower risk category than a diet on the other end. A lot of issues in food/health/nutrition are multi-variable/multi-parameter problems. That makes isolating single things as being a problem kind of hard to separate out because there are so many other factors you have to try to control for.
Smoking your oil is a concern, but from what I read a lot of issues have little to do with the oil itself. Effectively frying creates other components from the food and temperatures (even lower frying temperatures) that come with all sorts of health risks.
Frying simply seems to compound a lot of things together resulting in the increased health risks.
Having said that as unhealthy as eating fried foods is there certainly are ways to make it increasingly unhealthy. So lower temperatures, oils with higher smoke points, not reusing your oil are all things that will keep it on the lower end of the risk scale.
It still is best to avoid fried foods to just an incidental basis.
If this is true.
Then why do we talk about frying ever being “necessary” at all?
I have not fried any food for myself since at least 2015.
Okay, I see. If you are just here for the quick scoring bullet points, I'll pass on that.
As I have already made very clear, it is actually a much more complex subject than just "these oils are good, these are bad, case closed".
Not who you asked.
Necessary is probably a wrong word to use, but a significant percentage of people choose comfort, familiarity, taste and other factors that increase pleasure over pure health.
Smokers and drinkers still exist in spite of clear science that indulging is less healthy than abstaining.
It also doesn't seem to be a huge concern if you eat the incidental fried dish as it appears to be dose-dependent. So high frequency and high volume intake.
It also a bit of a shift of a goal post as far as I am concerned. The health risks associated with frying food is worthwhile conversation to have. But, while related, still a separate conversation to have.
Also, even when you take frying foods out of the equation it still doesn't make it much simpler. Far from it.
Fried foods are staples of sorts in some cultures too, and cutting back on or leaving behind what one was raised with can be rough. In my case, having been born in Appalachia, dishes like fried potatoes, fried yellow squash, and fried chicken were common and as I understand it, that only intensifies as you go further south.