Oh, I wasn't aware of that. But having read through it, I don't think responding to it would be very productive. The arguments in that post are mostly part of the standard "seed oil canon", meaning I'd seen similar arguments before writing my post above, and I've basically said what I have to say about them. For example, I'm happy for people to read my argument that mechanistic reasoning is unreliable and then that argument that it is reliable, and then decide for themselves. I definitely stand by my position, but I have no new arguments beyond those I've already made.
I don't have the time to refute all of the points but let me clear up some things.
1) There is one "seed oil theory" and it's not made up by randos on the internet, but by very real biochemists like Raymond Peat, Brad Marshall, Dr. Mercola, Kyle Mamounis and others. The theory is simple: PUFAs, especially linoleic acid, create poses a toxic risks to our system. Linoleic acid is not a danger in itself, the danger happens when it's oxydized. That's why measuring it in the blood is not a reliable marker and why we lack a good all-encompassing health marker for this.
2) There is debate as to whether or not EPA and DHA are also as harmful as linoleic acid. This is a niche debate no relevant to the overall point.
3) There is also a notable difference between rancid, heated, oxydized oils and non-rancid. Seasoning your salad with seed oils is very different than getting a bag of potato chips (which, you know, have been found to be, by a large margin, the most fattening food by Mozaffarian et al 2011 [even though he tried to hide the results]). In the first case, your body will go out of its way to burn the PUFAs as soon as it can (almost like it is scared of PUFAs...). In the second, you absorb toxic byproducts of the frying process, chiefly 4-hydroxynonenal (just put "HNE" in Google Scholar...), which seems much less desirable.
4) Since we've been drowning in them for decades, there is no control population. All industrial rich country rely massively on processed food, in which heated seed rancid PUFAs are present. No way to escape this. So any intervention study with no control group is useless at best.
5) Only way to be certain of any harm is by looking at pristine hunter-gatherer communities with no modern disease. There's plenty, and the correlation is clear (no seed oils, no metabolic syndrome problem), except for one -- one San bushmen tribe has seasonal diabetes. The main staple of their food during the season when they become diabetic? Litteral seeds made up of 40% linoleic acid.
6) It might very well be that these undesirable effects are triggered above a certain absolute threshold. At least that's what the aforementioned studies suggest (they never consume more than 2% of kcal as n-6s). If that is, we've far overblown above it.
7) In the context of an overweight population whose adipose tissue is full of PUFAs, there is no way to tell if any dietary intervention has any relevant result. Sugar may be bad in the context of seed oil soaked food. But outside of it? We don't know (actually we know if we look at hunter gatherer and older population studies -- spoiler it doesn't seem to be a problem). Same for saturated fat.
(Side note: storing n-6s in adipose tissue is a way for the body to avoid the danger of lipid peroxydation in cell membranes.)
8) Saturated fat and sugar consumption clearly stalled for the last 20, 30 years. Sugar is down from year 2000 and sat fat were largely replaced. Why do we keep getting fatter *at an even more exponential rate* ? (compare 2000-2010 to 2010-2020) Something doesn't add up.
9) Correlation is not causation, but it is by far the strongest correlation we see. A search for "history of seed oils" on YouTube will get you to Nina Teicholz talk and you'll see that edible seed oils litterally appeared in 1910, the first Crisco recipe book was published in 1911. Sure it was full of trans fat, so this might be a confounder which explains the early timid rise of the 1920s.
10) I've never seen anyone sell me something anti-seed oil-related. On TV, I hear food manufacturers selling us their cheaper vegetable oil, supposedly because it is "heart-healthy". Being far cheaper than any other kind of fat, you bet it is!
11) The Sydney Diet Heart study has been ommitted from several meta analysis, notably from the Cochrane review, known for its rigorous work. I agree that the Minnesota experiment wasn't the best designed study.
12) Blood n-6 level is a very unreliable marker. Diet predicts about 20% of the variation of blood n-6.
On inflammation, the data is very inconsistent because of genetic variables. To say "there are no study showing increased inflammation marker as the result of n-6 consumption" is simply false. Namely, a mutation in the D6D enzyme (CC, CT/TC and TT genotypes) is responsible for the fact that 20% of people are more resistant to diabetes and heart diseases while having upregulated CRP activity with n-6 consumption. Inversely, 30% of people have higher risk but decreased CRP activity in the same scenario. So ignoring this aspect, these results makes no sense.
13) There's a pretty visible correlation between n-6s and obesity in those graphs of yours. However I haven't looked at the way they got the information about n-6 consumption.
14) I'm french. We're told to limit saturated fat. We also have a important dairy industry on which a good part of our internationally renowned cuisine relies. For the most part we're not shy on butter or cheese despite what the health authorities tell us. We're also the thinnest of Europe with the italians (same average BMI as of 2012 iirc). I went to the USA once, and the amount of fat people simply was unbelievable. You have seed oils in literally every food, even basic bread. If you don't call this a paradox, I don't know what is. There's also the Israeli paradox (it's the other way around).
Sorry for the messy writing!
PS: It turned out I took the time to write this up \o/
Re 1: If there is one true seed oil theory, where is it written down? Can you point me to a single canonical document that seed oil people all endorse?
Re 5: The trouble here is that the diets of hunter-gatherers differ along many other dimensions than just seed oils.
Re: 11. Are you asserting that the Sydney Diet Heart Study was excluded from the Cochrane review? If so, that's definitely not true. (I included pictures of tables in the document.)
(Also, fair warning: I let the accusation of dishonesty slide this time, but I will remove any further comments with accusations of bad faith. I'd appreciate it if you would edit your message to remove that.)
1) It's such a rich topic that it's hard to point to any one work... Cate Shanahan has something coming up soon. Chris Knobbe has supposedly good stuff but more targeted towards the general public, most likely doesn't get into the biochem details of it. Maybe the Zero Acre Farm white papers? (not technical either)
Raymond Peat definitely has some good detailed papers.
The bulk of the argument lies in hours of YouTube debates I'm afraid, until someone writes all of this down. And hundreds of scientific papers.
5) I agree, it's a mess... They all have this low seed oils consumption in common and the exception is a tribe that gets seasonally insulin resistant, and per Ben Bikman I think insulin resistance is the crucial indicator of metabolic dysfunction.
Also I forgot to mention something important: animal studies are clearly supportive of the seed oils bad argument. That's pretty much how Peat made his case at the time.
Overall it is a challenging field. it's easy to spend time policing people peddling false certainty, which is an important role of real science. But hard to find real answers. Which is the MOST important role of science.
The problem isn't on the food side, as you say. It's that cellular biology makes rocket science look like tic-tac-toe and we are a very long way from understanding mammalian metabolism. it's a clustercuss in there. What do mitochondria do? we know they're the powerhouse of the cell, which is about 10% of the answer. They have SUCH complex roles. Peroxisomes? they've barely been studied. etc etc. What are lipid droplets, do they count as organelles? (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3039932/) Why do they have such powerful roles in immune response? etc.
So that's part of the problem here. Another part is we mix up the questions. The question people want to answer is "Should I eat seed oils?" and they operationalise that as "do they cause obesity?" while at other times they ask about mortality and other health risks. Neither sub-question is well answered but flipping between them to answer the meta question only confuses.
An interesting hypothesis I saw is that the unsaturated fats are dangerous when they get oxidised (those unsaturated bonds oxidise easily) and so eating unsaturated fats may be a super bad idea if you smoke.
The heart risk angle of unsaturated fats would therefore be additive: you need to eat seed oils and smoke (or be exposed to a lot of pollution). We'd expect this effect of unsaturated fats to be present in older studies with more smokers, missing in newer studies with fewer smokers and obscured by meta analyses that combine old and new. This is just one way in which our understanding might be obscured!
To be fair to canola oil, you can press and extract it in the same way you describe extracting olive oil. As far as I know, hexane is also used in olive oil production to improve yields. I get that you're steelmanning the seed oil argument, but I suspect any food oil production can be described in *wholesome, friendly, DIY* terms or *scary, modern industrial yield maximization and purification* terms.
I've been avoiding seed oil for a while now. The seed oil movement reminds me a lot of, well, plenty of other diet movements. Kind of like how there are compelling ideas put forth about how vegetables are good for health, which then get tarnished when a large group of nutcases run around screaming about how a Whole Food Plant Diet will cure all cancer and allow you to communicate with spiritual beings. 90% of everything is crap and I think that applies to the proponents of diet concepts too: every promising concept out there inevitably attracts its nutbag group that loudly and overconfidently makes the whole thing look stupid.
It's definitely important to be mindful of falling into unfalsifiable Invisible Garage Dragon-type games with concepts we're attached to. Still, when it comes to obesity, I think the fact that we've done all this work and research and still haven't been able to make a dent in obesity rates is a sign that the solutions are probably unintuitive and we're probably grossly misinterpreting the data we have. The field of nutrition has a long history of misinterpreting short-term data points and making inappropriate predictions about how they might influence long-term hard endpoints like disease or death. According to several surveys, Americans have been exercising more and "eating better" than they used to decades ago: if obesity actually worked like mainstream nutrition thinks it does, we should have seen results from this, not exponential worsening of the problem. We're clearly doing SOMETHING wrong, and seed oil theories seem to provide some compelling ideas about why things are continuing to go sideways at such an alarming rate. That's why I perk up when I see things like rat studies where the seed-oil-fed rats have "great-looking biomarkers" in the short term, but then deeper examination reveals they actually developed NAFLD and atherosclerosis at higher rates than saturated-fat-fed rats. If we've been fooled by simplistic interpretations of observations done on an already PUFA-oversaturated population, it would go a long way towards explaining why our current definition of "healthy diet and lifestyle" - which is being adhered to more now than before! - is overall producing ass-backward results.
Anyway, fantastic article and a great reminder not to be dogmatic and to keep an open mind even if an idea is super exciting. I'm obviously biased... trans fats used to be lauded as healthy and people who raised concerns about them were called unscientific. It's not hard at all for me to imagine we might be completely wrong about seed oils too, considering our track record. But we need to be able to produce real results and proof. I'm very interested to see where all this research goes in the next decade or so.
On the wider and more interesting question of "what went wrong", I agree that singe-cause explanations are not very believable. But in very broad terms, in the last century or so humanity has been hyper-optimizing all sorts of things. From capital usage, competition and advertising, to land yields and fabrication recipes, everything is now hyper optimized, or it just can't compete in the mainstream. Not to idealize or simplify the past too much, but nothing used to be so relentlessly optimized. Cultures would vary from one place to the next instead of being all in contact and competition, innovation was slow, expectations were much lower, and there weren't just that many people around to be fed and sold to.
And what happens in a dynamic system when you optimize for a subset of parameters, is that the *rest* of the parameters just jump around randomly. If there was some kind of cultural selection pressure keeping them within some bounds, it gets overwhelmed and is no longer operative.
So I'm not surprised that the result is what some people nowadays call a "polycrisis". Everything that isn't being directly optimized for by the economic system is just slowly going out of whack, from the Earth's climate to our physical and mental health, to the sanity of cultural output. It's Cory Doctorow's enshitiffication, but on the broadest scale.
And on the practical terms of "what can I do with the moderate amount of effort that I'm willing to put on this", I basically agree with Dynomight and other commenters' suggestions. At home we just use cold-pressed olive oil for everything; it's not some hard won virtue over here in Spain, it's just what my parents and their parents used to do, we're lucky the this particular continuity didn't get broken. Drink mostly water or teas (herbal or regular), eat plenty of vegetables, etc. And for home usage I try to avoid stuff with ingredients someone's great grandma wouldn't recognize - we get enough of that shit when eating out.
Great post, but isn’t using BMI for global comparisons problematic due to between-race variance in how well it correlates with obesity/bad health outcomes?
The origin of schools of thought like the seed oil one are pretty fascinating. Like why did people skip by the more straightforward stuff like calories in and out, glycemic index, highly palatable food, and nutrients? I mean, I guess I know the answer - it's because the basic answers are kind of boring and it's much more fun to have access to special knowledge that makes you special and also presents a workaround to boring stuff like eating less. And sometimes the special knowledge turns out to be true.
Overall, I guess I'm glad that we have people going off on weird tangents like seed oils, lithium in the water, and potato diets, but most of the time they're going to come to nothing. They're very low probability, high payoff bets.
I also continue to be amazed by how hard it is to really know anything in epidemiology. We've done, what, 30/50/100 studies on seed oils? And the answer we come out with after careful consideration for what seed oils do is, "Hmm, not quite sure, probably nothing in particular." I guess that's just how it is, but sometimes it makes me laugh/cry.
One reason why calories in/calories out has come into question is because aggregate food supply data show that calories per person have flattened, yet obesity continues to rise in an unmitigated fashion.
Similarly, sugar supply has tanked over the past 20 years while obesity has climbed.
To me the bigger mystery is why there is so much geographical variation *within* countries. Calories can’t explain that, neither can seed oils (probably).
Do you have a source that calories/person have flattened? I just checked the FAO data (where most people seem to get these numbers: https://www.fao.org/faostat/en/#data/FBS) and here's what they have for kcal/cap/d for the US in the last few years:
2010: 3729
2011: 3727
2012: 3765
2013: 3754
2014: 3742
2015: 3754
2016: 3777
2017: 3791
2018: 3824
2019: 3876
2020: 3892
2021: 3911
Pretty noisy, but looks like it's rising overall. But then... I guess this is only for calories "delivered" to people not necessarily consumed. (I can't believe people are actually consuming 3900 kcal/day on everage!)
Yes, I go to two sources: FAO [via "Our World In Data"] and the USDA Economic Research Service. I only had FAO up to 2017 so I didn't know of the recent uptick since then.
For the USDA ERS, it unfortunately cuts out at 2010 but here's what it reports:
2001: 2,546
2002: 2,574
2003: 2,566
2004: 2,566
2005: 2,551
2006: 2,554
2007: 2,562
2008: 2,543
2009: 2,469
2010: 2,501
I'm not sure why it's off by over 1,000 calories from the FAO data.
You can also get food diary data from NHANES. These show a completely flat trajectory since 2000 but not sure they are believable since it's self-reported food diary data, so easy to "forget" that you ate that extra handful of M&M's.
Unfortunately you have to click through and open each year's PDF to look at the data. I have an R script that goes through it and creates a chart that I'd be happy to share with you if you'd like.
Interestingly the food diary data shows an uptick of omega-6 PUFA consumption along with an uptick in the total disappearance of edible seed oils from the food supply data, but the levels are *way* off across the two.
The story gets even more interesting if you go back further. If you look at data from before 1960 (which is admittedly hard to come by), you'll find that we ate a lot more in, say, 1930 than we do today.
Wait, does it show that? That link shows that men in the heaviest labor roles were eating 3900 calories per day, and men in light labor roles much less. But the data above for 2021 suggests that the average over the *whole population* (women, children, men who are mostly not in heavy labor roles) was 3900.
Just to add to that. The main point the author there makes is that linoleic acid itself doesn’t necessarily make you fat. But it triggers torpor in animals to trigger pathways to start accumulating fat. It’s like a trigger from nature. Because usually linoleic acid rich foods are available around fall which is when animals need to store weight before the winter.
I have done a deeper dive on this than I care to admit, and where I landed was:
1. Olive oil and avocado oil are your best bet for everyday use in most applications.
2. Animal fats are okay *in moderation*. Don't go crazy. Avoid the non-animal highly saturated fats like coconut oil and palm oil.
3. Try to get some omega-3s. They are preferentially processed as compared to omega-6s, and the metabolic channel doesn't have infinite capacity. If you are processing omega-3s, you aren't processing omega-6s.
4. Avoid seed oils to the extent possible. But there's no need to be a zealot. Have some chips and queso when you're at the Mexican restaurant. It will be okay. There isn't a really good reason to believe that low level PUFA intake results in increased risks.
In practical terms, the regimen above is fairly conventional advice on diet (avoid junk food and eat lean proteins and vegetables and olive oil...Who knew??), and the downside risks seem to be slim to none.
My working theory is, more or less, PUFA intake above a certain threshold can interact with other diet and lifestyle factors to result in metabolic dysfunction that can cascade in lots of negative directions. It's tough to evaluate it all because, from an empirical perspective, the systems are absurdly complex and multi-variate and also because the impact of the hypothesized metabolic dysfunction is more in the way of long term chronic issues (diabetes, obesity, increased inflammation / cancer, etc.), whereas the benefits of replacing bad saturated fats with PUFAs is in the form of acute harm reduction (avoiding strokes, heart attacks, etc.).
Nice write-up. What is your source for the linoleic acid % in body composition over time? That's a very striking graph, but I'd like to know the source/methodology.
I think you've debunked it well enough. If you need to look TOO hard, you'll find what you're looking for because you get sloppy (as shown by your GDP data). The correlation that is easier to see is with "highly processed foods," meaning vending machine stuff, packaged muffins, that sort of thing. Obesity skyrocketed in Mexico after NAFTA made it possible to import said junk food in large, inexpensive quantities. I'll add this separate point: palm oil use is decimating jungles in Indonesia and other places, where jungles are being cut down for palm plantations. So... choose your (or the Earth's) poison.
Not sceptical enough, IMO.
This is the best analysis of this hysteria i've read yet. Thank you !
probably already on your radar, but are you open to responding to this :^) https://www.exfatloss.com/p/a-reply-to-dynomights-thoughts-on
Oh, I wasn't aware of that. But having read through it, I don't think responding to it would be very productive. The arguments in that post are mostly part of the standard "seed oil canon", meaning I'd seen similar arguments before writing my post above, and I've basically said what I have to say about them. For example, I'm happy for people to read my argument that mechanistic reasoning is unreliable and then that argument that it is reliable, and then decide for themselves. I definitely stand by my position, but I have no new arguments beyond those I've already made.
got it thanks!
Kudos for writing this.
I don't have the time to refute all of the points but let me clear up some things.
1) There is one "seed oil theory" and it's not made up by randos on the internet, but by very real biochemists like Raymond Peat, Brad Marshall, Dr. Mercola, Kyle Mamounis and others. The theory is simple: PUFAs, especially linoleic acid, create poses a toxic risks to our system. Linoleic acid is not a danger in itself, the danger happens when it's oxydized. That's why measuring it in the blood is not a reliable marker and why we lack a good all-encompassing health marker for this.
2) There is debate as to whether or not EPA and DHA are also as harmful as linoleic acid. This is a niche debate no relevant to the overall point.
3) There is also a notable difference between rancid, heated, oxydized oils and non-rancid. Seasoning your salad with seed oils is very different than getting a bag of potato chips (which, you know, have been found to be, by a large margin, the most fattening food by Mozaffarian et al 2011 [even though he tried to hide the results]). In the first case, your body will go out of its way to burn the PUFAs as soon as it can (almost like it is scared of PUFAs...). In the second, you absorb toxic byproducts of the frying process, chiefly 4-hydroxynonenal (just put "HNE" in Google Scholar...), which seems much less desirable.
4) Since we've been drowning in them for decades, there is no control population. All industrial rich country rely massively on processed food, in which heated seed rancid PUFAs are present. No way to escape this. So any intervention study with no control group is useless at best.
5) Only way to be certain of any harm is by looking at pristine hunter-gatherer communities with no modern disease. There's plenty, and the correlation is clear (no seed oils, no metabolic syndrome problem), except for one -- one San bushmen tribe has seasonal diabetes. The main staple of their food during the season when they become diabetic? Litteral seeds made up of 40% linoleic acid.
6) It might very well be that these undesirable effects are triggered above a certain absolute threshold. At least that's what the aforementioned studies suggest (they never consume more than 2% of kcal as n-6s). If that is, we've far overblown above it.
7) In the context of an overweight population whose adipose tissue is full of PUFAs, there is no way to tell if any dietary intervention has any relevant result. Sugar may be bad in the context of seed oil soaked food. But outside of it? We don't know (actually we know if we look at hunter gatherer and older population studies -- spoiler it doesn't seem to be a problem). Same for saturated fat.
(Side note: storing n-6s in adipose tissue is a way for the body to avoid the danger of lipid peroxydation in cell membranes.)
8) Saturated fat and sugar consumption clearly stalled for the last 20, 30 years. Sugar is down from year 2000 and sat fat were largely replaced. Why do we keep getting fatter *at an even more exponential rate* ? (compare 2000-2010 to 2010-2020) Something doesn't add up.
9) Correlation is not causation, but it is by far the strongest correlation we see. A search for "history of seed oils" on YouTube will get you to Nina Teicholz talk and you'll see that edible seed oils litterally appeared in 1910, the first Crisco recipe book was published in 1911. Sure it was full of trans fat, so this might be a confounder which explains the early timid rise of the 1920s.
10) I've never seen anyone sell me something anti-seed oil-related. On TV, I hear food manufacturers selling us their cheaper vegetable oil, supposedly because it is "heart-healthy". Being far cheaper than any other kind of fat, you bet it is!
11) The Sydney Diet Heart study has been ommitted from several meta analysis, notably from the Cochrane review, known for its rigorous work. I agree that the Minnesota experiment wasn't the best designed study.
12) Blood n-6 level is a very unreliable marker. Diet predicts about 20% of the variation of blood n-6.
On inflammation, the data is very inconsistent because of genetic variables. To say "there are no study showing increased inflammation marker as the result of n-6 consumption" is simply false. Namely, a mutation in the D6D enzyme (CC, CT/TC and TT genotypes) is responsible for the fact that 20% of people are more resistant to diabetes and heart diseases while having upregulated CRP activity with n-6 consumption. Inversely, 30% of people have higher risk but decreased CRP activity in the same scenario. So ignoring this aspect, these results makes no sense.
13) There's a pretty visible correlation between n-6s and obesity in those graphs of yours. However I haven't looked at the way they got the information about n-6 consumption.
14) I'm french. We're told to limit saturated fat. We also have a important dairy industry on which a good part of our internationally renowned cuisine relies. For the most part we're not shy on butter or cheese despite what the health authorities tell us. We're also the thinnest of Europe with the italians (same average BMI as of 2012 iirc). I went to the USA once, and the amount of fat people simply was unbelievable. You have seed oils in literally every food, even basic bread. If you don't call this a paradox, I don't know what is. There's also the Israeli paradox (it's the other way around).
Sorry for the messy writing!
PS: It turned out I took the time to write this up \o/
Re 1: If there is one true seed oil theory, where is it written down? Can you point me to a single canonical document that seed oil people all endorse?
Re 5: The trouble here is that the diets of hunter-gatherers differ along many other dimensions than just seed oils.
Re: 11. Are you asserting that the Sydney Diet Heart Study was excluded from the Cochrane review? If so, that's definitely not true. (I included pictures of tables in the document.)
(Also, fair warning: I let the accusation of dishonesty slide this time, but I will remove any further comments with accusations of bad faith. I'd appreciate it if you would edit your message to remove that.)
1) It's such a rich topic that it's hard to point to any one work... Cate Shanahan has something coming up soon. Chris Knobbe has supposedly good stuff but more targeted towards the general public, most likely doesn't get into the biochem details of it. Maybe the Zero Acre Farm white papers? (not technical either)
Raymond Peat definitely has some good detailed papers.
The bulk of the argument lies in hours of YouTube debates I'm afraid, until someone writes all of this down. And hundreds of scientific papers.
5) I agree, it's a mess... They all have this low seed oils consumption in common and the exception is a tribe that gets seasonally insulin resistant, and per Ben Bikman I think insulin resistance is the crucial indicator of metabolic dysfunction.
Also I forgot to mention something important: animal studies are clearly supportive of the seed oils bad argument. That's pretty much how Peat made his case at the time.
11) I do not assert that.
(I removed the mention, sorry about that!)
Overall it is a challenging field. it's easy to spend time policing people peddling false certainty, which is an important role of real science. But hard to find real answers. Which is the MOST important role of science.
The problem isn't on the food side, as you say. It's that cellular biology makes rocket science look like tic-tac-toe and we are a very long way from understanding mammalian metabolism. it's a clustercuss in there. What do mitochondria do? we know they're the powerhouse of the cell, which is about 10% of the answer. They have SUCH complex roles. Peroxisomes? they've barely been studied. etc etc. What are lipid droplets, do they count as organelles? (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3039932/) Why do they have such powerful roles in immune response? etc.
So that's part of the problem here. Another part is we mix up the questions. The question people want to answer is "Should I eat seed oils?" and they operationalise that as "do they cause obesity?" while at other times they ask about mortality and other health risks. Neither sub-question is well answered but flipping between them to answer the meta question only confuses.
An interesting hypothesis I saw is that the unsaturated fats are dangerous when they get oxidised (those unsaturated bonds oxidise easily) and so eating unsaturated fats may be a super bad idea if you smoke.
The heart risk angle of unsaturated fats would therefore be additive: you need to eat seed oils and smoke (or be exposed to a lot of pollution). We'd expect this effect of unsaturated fats to be present in older studies with more smokers, missing in newer studies with fewer smokers and obscured by meta analyses that combine old and new. This is just one way in which our understanding might be obscured!
To be fair to canola oil, you can press and extract it in the same way you describe extracting olive oil. As far as I know, hexane is also used in olive oil production to improve yields. I get that you're steelmanning the seed oil argument, but I suspect any food oil production can be described in *wholesome, friendly, DIY* terms or *scary, modern industrial yield maximization and purification* terms.
Mm damn a great analysis on this; been hearing more on seed oils online! Thanks :)
I've been avoiding seed oil for a while now. The seed oil movement reminds me a lot of, well, plenty of other diet movements. Kind of like how there are compelling ideas put forth about how vegetables are good for health, which then get tarnished when a large group of nutcases run around screaming about how a Whole Food Plant Diet will cure all cancer and allow you to communicate with spiritual beings. 90% of everything is crap and I think that applies to the proponents of diet concepts too: every promising concept out there inevitably attracts its nutbag group that loudly and overconfidently makes the whole thing look stupid.
It's definitely important to be mindful of falling into unfalsifiable Invisible Garage Dragon-type games with concepts we're attached to. Still, when it comes to obesity, I think the fact that we've done all this work and research and still haven't been able to make a dent in obesity rates is a sign that the solutions are probably unintuitive and we're probably grossly misinterpreting the data we have. The field of nutrition has a long history of misinterpreting short-term data points and making inappropriate predictions about how they might influence long-term hard endpoints like disease or death. According to several surveys, Americans have been exercising more and "eating better" than they used to decades ago: if obesity actually worked like mainstream nutrition thinks it does, we should have seen results from this, not exponential worsening of the problem. We're clearly doing SOMETHING wrong, and seed oil theories seem to provide some compelling ideas about why things are continuing to go sideways at such an alarming rate. That's why I perk up when I see things like rat studies where the seed-oil-fed rats have "great-looking biomarkers" in the short term, but then deeper examination reveals they actually developed NAFLD and atherosclerosis at higher rates than saturated-fat-fed rats. If we've been fooled by simplistic interpretations of observations done on an already PUFA-oversaturated population, it would go a long way towards explaining why our current definition of "healthy diet and lifestyle" - which is being adhered to more now than before! - is overall producing ass-backward results.
Anyway, fantastic article and a great reminder not to be dogmatic and to keep an open mind even if an idea is super exciting. I'm obviously biased... trans fats used to be lauded as healthy and people who raised concerns about them were called unscientific. It's not hard at all for me to imagine we might be completely wrong about seed oils too, considering our track record. But we need to be able to produce real results and proof. I'm very interested to see where all this research goes in the next decade or so.
Saturated fat has no effect on overall mortality according to the meta
https://sci-hub.se/10.1002/14651858.CD011737.pub3
That meta analysis is discussed at length in the article: https://dynomight.net/seed-oil/#the-inside-view
On the wider and more interesting question of "what went wrong", I agree that singe-cause explanations are not very believable. But in very broad terms, in the last century or so humanity has been hyper-optimizing all sorts of things. From capital usage, competition and advertising, to land yields and fabrication recipes, everything is now hyper optimized, or it just can't compete in the mainstream. Not to idealize or simplify the past too much, but nothing used to be so relentlessly optimized. Cultures would vary from one place to the next instead of being all in contact and competition, innovation was slow, expectations were much lower, and there weren't just that many people around to be fed and sold to.
And what happens in a dynamic system when you optimize for a subset of parameters, is that the *rest* of the parameters just jump around randomly. If there was some kind of cultural selection pressure keeping them within some bounds, it gets overwhelmed and is no longer operative.
So I'm not surprised that the result is what some people nowadays call a "polycrisis". Everything that isn't being directly optimized for by the economic system is just slowly going out of whack, from the Earth's climate to our physical and mental health, to the sanity of cultural output. It's Cory Doctorow's enshitiffication, but on the broadest scale.
And on the practical terms of "what can I do with the moderate amount of effort that I'm willing to put on this", I basically agree with Dynomight and other commenters' suggestions. At home we just use cold-pressed olive oil for everything; it's not some hard won virtue over here in Spain, it's just what my parents and their parents used to do, we're lucky the this particular continuity didn't get broken. Drink mostly water or teas (herbal or regular), eat plenty of vegetables, etc. And for home usage I try to avoid stuff with ingredients someone's great grandma wouldn't recognize - we get enough of that shit when eating out.
Great post, but isn’t using BMI for global comparisons problematic due to between-race variance in how well it correlates with obesity/bad health outcomes?
The origin of schools of thought like the seed oil one are pretty fascinating. Like why did people skip by the more straightforward stuff like calories in and out, glycemic index, highly palatable food, and nutrients? I mean, I guess I know the answer - it's because the basic answers are kind of boring and it's much more fun to have access to special knowledge that makes you special and also presents a workaround to boring stuff like eating less. And sometimes the special knowledge turns out to be true.
Overall, I guess I'm glad that we have people going off on weird tangents like seed oils, lithium in the water, and potato diets, but most of the time they're going to come to nothing. They're very low probability, high payoff bets.
I also continue to be amazed by how hard it is to really know anything in epidemiology. We've done, what, 30/50/100 studies on seed oils? And the answer we come out with after careful consideration for what seed oils do is, "Hmm, not quite sure, probably nothing in particular." I guess that's just how it is, but sometimes it makes me laugh/cry.
One reason why calories in/calories out has come into question is because aggregate food supply data show that calories per person have flattened, yet obesity continues to rise in an unmitigated fashion.
Similarly, sugar supply has tanked over the past 20 years while obesity has climbed.
To me the bigger mystery is why there is so much geographical variation *within* countries. Calories can’t explain that, neither can seed oils (probably).
Do you have a source that calories/person have flattened? I just checked the FAO data (where most people seem to get these numbers: https://www.fao.org/faostat/en/#data/FBS) and here's what they have for kcal/cap/d for the US in the last few years:
2010: 3729
2011: 3727
2012: 3765
2013: 3754
2014: 3742
2015: 3754
2016: 3777
2017: 3791
2018: 3824
2019: 3876
2020: 3892
2021: 3911
Pretty noisy, but looks like it's rising overall. But then... I guess this is only for calories "delivered" to people not necessarily consumed. (I can't believe people are actually consuming 3900 kcal/day on everage!)
Here's a document of charts I put together: https://raw.githack.com/tyleransom/obesity-graphs/master/writeup/graphs.pdf
You can find all data + code underlying the document here on GitHub: https://github.com/tyleransom/obesity-graphs
Interesting. I haven't looked into this in detail, but it seems like the FAO had a significant shift in methodology in 2010, might explain the reversal of the trend there? https://fenixservices.fao.org/faostat/static/documents/FBS/Key%20differences%20between%20new%20and%20old%20FBS%20June2022%20.pdf
(But that wouldn't explain the local maxima in 2006...)
Yes, I was vaguely aware of the methodological shift in 2010 but haven't looked too deeply into what it would mean. Thanks for sharing!
Yes, I go to two sources: FAO [via "Our World In Data"] and the USDA Economic Research Service. I only had FAO up to 2017 so I didn't know of the recent uptick since then.
The USDA ERS link is here (go to "Totals" tab): https://view.officeapps.live.com/op/view.aspx?src=https%3A%2F%2Fwww.ers.usda.gov%2Fwebdocs%2FDataFiles%2F50472%2Fcalories.xls%3Fv%3D6095.7&wdOrigin=BROWSELINK
The above link can be accessed by visiting the following link and then clicking on "Calories": https://www.ers.usda.gov/data-products/food-availability-per-capita-data-system/
For the USDA ERS, it unfortunately cuts out at 2010 but here's what it reports:
2001: 2,546
2002: 2,574
2003: 2,566
2004: 2,566
2005: 2,551
2006: 2,554
2007: 2,562
2008: 2,543
2009: 2,469
2010: 2,501
I'm not sure why it's off by over 1,000 calories from the FAO data.
You can also get food diary data from NHANES. These show a completely flat trajectory since 2000 but not sure they are believable since it's self-reported food diary data, so easy to "forget" that you ate that extra handful of M&M's.
The NHANES source is "What We Eat In America" here: https://www.ars.usda.gov/northeast-area/beltsville-md-bhnrc/beltsville-human-nutrition-research-center/food-surveys-research-group/docs/wweia-data-tables/
Unfortunately you have to click through and open each year's PDF to look at the data. I have an R script that goes through it and creates a chart that I'd be happy to share with you if you'd like.
Interestingly the food diary data shows an uptick of omega-6 PUFA consumption along with an uptick in the total disappearance of edible seed oils from the food supply data, but the levels are *way* off across the two.
Thanks. I guess I'll classify this as ambiguous for now.
Which, to be clear, is a shift from my expectations—I would have thought calorie consumption was unambiguously going up!
The story gets even more interesting if you go back further. If you look at data from before 1960 (which is admittedly hard to come by), you'll find that we ate a lot more in, say, 1930 than we do today.
unfashionable.blog/p/obesity
Wait, does it show that? That link shows that men in the heaviest labor roles were eating 3900 calories per day, and men in light labor roles much less. But the data above for 2021 suggests that the average over the *whole population* (women, children, men who are mostly not in heavy labor roles) was 3900.
Have you reviewed the works of Fire in a bottle and the surrounding community? Lots of good meta research on this topic.
Just to add to that. The main point the author there makes is that linoleic acid itself doesn’t necessarily make you fat. But it triggers torpor in animals to trigger pathways to start accumulating fat. It’s like a trigger from nature. Because usually linoleic acid rich foods are available around fall which is when animals need to store weight before the winter.
I have done a deeper dive on this than I care to admit, and where I landed was:
1. Olive oil and avocado oil are your best bet for everyday use in most applications.
2. Animal fats are okay *in moderation*. Don't go crazy. Avoid the non-animal highly saturated fats like coconut oil and palm oil.
3. Try to get some omega-3s. They are preferentially processed as compared to omega-6s, and the metabolic channel doesn't have infinite capacity. If you are processing omega-3s, you aren't processing omega-6s.
4. Avoid seed oils to the extent possible. But there's no need to be a zealot. Have some chips and queso when you're at the Mexican restaurant. It will be okay. There isn't a really good reason to believe that low level PUFA intake results in increased risks.
In practical terms, the regimen above is fairly conventional advice on diet (avoid junk food and eat lean proteins and vegetables and olive oil...Who knew??), and the downside risks seem to be slim to none.
My working theory is, more or less, PUFA intake above a certain threshold can interact with other diet and lifestyle factors to result in metabolic dysfunction that can cascade in lots of negative directions. It's tough to evaluate it all because, from an empirical perspective, the systems are absurdly complex and multi-variate and also because the impact of the hypothesized metabolic dysfunction is more in the way of long term chronic issues (diabetes, obesity, increased inflammation / cancer, etc.), whereas the benefits of replacing bad saturated fats with PUFAs is in the form of acute harm reduction (avoiding strokes, heart attacks, etc.).
Nice write-up. What is your source for the linoleic acid % in body composition over time? That's a very striking graph, but I'd like to know the source/methodology.
I think you've debunked it well enough. If you need to look TOO hard, you'll find what you're looking for because you get sloppy (as shown by your GDP data). The correlation that is easier to see is with "highly processed foods," meaning vending machine stuff, packaged muffins, that sort of thing. Obesity skyrocketed in Mexico after NAFTA made it possible to import said junk food in large, inexpensive quantities. I'll add this separate point: palm oil use is decimating jungles in Indonesia and other places, where jungles are being cut down for palm plantations. So... choose your (or the Earth's) poison.