← What's That Rash?
What's That Rash?
Why is everyone suddenly talking about seed oils?
00:20:02
It can be hard to keep up with food fads and diet trends (and spoiler: you don’t need to). But an intriguing assumption that has gained traction recently is that seed oils – think canola, sunflower, grapeseed – are terrible for you. Norman and Tegan unpack how that assumption has spread, and whether there’s any solid evidence to back it up. References: Biomarkers of Dietary Omega-6 Fatty Acids and Incident Cardiovascular Disease and Mortality Serum n-6 polyunsaturated fatty acids and risk of death: the Kuopio Ischaemic Heart Disease Risk Factor Study Omega-6 fats to prevent and treat heart and circulatory diseases Polyunsaturated fatty acids intake and risk of all-cause mortality, cardiovascular disease, breast cancer, mental health, and type 2 diabetes: A systematic review and meta-analysis of prospective cohort studies Perspective on the health effects of unsaturated fatty acids and commonly consumed plant oils high in unsaturated fat If you’re worried about inflammation, stop...
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- [00:01]
A
Listen. That's the sound of the fully electric Audi Q6E Tron. The sound of captivating electric performance, dynamic drive and the quiet confidence of ultra smooth handling. The elevated interior reminds you this is more than an EV. This is electric performance. Redefined. The fully electric Audi Q6E Tron.
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B
ABC. Listen. Podcasts, radio, news, music and more. Norman, it pains me to ask you this because I have forgotten my Mediterranean diet bell today.
- [00:43]
C
Ting.
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B
That's it. I was going to ask you what your favourite oil is to cook with.
- [00:48]
C
Well, you kind of know what it is already. It's olive oil.
- [00:51]
B
Exactly. I know.
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C
Ding, ding, but only at low. Only at low temperature, following that sort of moderate heat type recipe. If it's high heat, it's a different story.
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B
What do you go for?
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C
I go for canola. Which in fact leads into today's episode of what's that Rash? Where we answer your questions.
- [01:06]
B
Let's get into it. So Peter has written in saying RFK I. E. Robert F. Kennedy Jr. Who's Trump's pick for health secretary in the US has stated that people are being poisoned by seed oils and has implied animal fats would be a preferable alternative. People in my life who have expressed similar views, I know that over the last few decades, production of seed oils has increased dramatically and our consumption must now be much higher than in traditional. This is what Peter writes. Ding. Diet based around olive oil. Peter personally loves olive oil, uses it whenever he can. But on the other hand, he's not worried if seed oils are called for in a recipe or in the ingredients list. Should I be? He asks, and he finishes by saying, to preempt the obvious pun, could you give us the good oil on this, please?
- [01:56]
C
You must be disappointed in that because somebody else has stolen your pun.
- [02:00]
B
Well, yes, and you know, I do love a pun, but I'm going to give this one to Peter because it was clever. So it'd be good to first start with a bit of a definition of what we're talking about. When we're talking about seed oils, we're.
- [02:12]
C
Talking about oils which are pressed or manufactured from seeds. So sunflower seeds, flax seeds, sesame seeds, peanuts. Some people would even say olive oil might even be considered a seed oil, but it's not really. It's the oil of the fruit. You're not really getting the seed in the middle. So it's oils made from those seeds.
- [02:33]
B
And canola is the big one. Or at least in Australia, we're a big manufacturer of canola oil.
- [02:37]
C
Yeah, canola is a big One internationally, but peanut's pretty big, as is rice bran oil. So when you go into the supermarket, there's a lot of seed oils there. And those are the oils that are being, if you like, condemned by Robert F Kennedy Jr and some others for various reasons.
- [02:55]
B
So oils, by definition, are really high in calories, like they're very high in energy, sort of no matter where they're coming from. What is it about seed oils specifically that seems to be the problem? Is it a paleo diet thing? Cause if it is, I've got ammunition.
- [03:11]
C
Well, let's do the paleo diet first. Cause there's a lot of misconception about the paleo diet. I mean, seed oils are not really new.
- [03:19]
B
No. And a few years ago, some years ago now, I interviewed an academic from the University of Minnesota who had a wonderful term she called paleo fantasy. And this idea that we kind of romanticise this period in human history where humans sort of were one with nature and we were eating what our bodies were evolved to eat. And that since then, with the agricultural revolution, the Industrial revolution, all that sort of stuff, we're now not living in harmony with nature. And she pushes back against that, she's an evolutionary biologist, by basically saying humans have never lived in harmony with nature, we're constantly adapting to it. That's what evolution means. And in addition to that, that sense that perhaps we're not living the way we were, quote, unquote, evolved to eat, is the fact that seeds have been part of human diets for, well, hominid diets for millions of years. There's evidence that even before sapiens existed as a species, that seeds were part of the diets of early human ancestors. So maybe not in the volumes, definitely not in the volumes that we eat them today, but they're not new to human diets like you say.
- [04:23]
C
No, indeed. And it's not just the oils, it's the carbohydrates as well. And they were processing carbohydrates. Really interesting recent study on hominids suggesting that they were processing quite complex carbohydrates to eat, and seeds would have been part of that. So the debate about this is about the fats in seed oils.
- [04:43]
B
Okay, so breaking down different types of fat, then. So what are we looking at?
- [04:47]
C
Well, let's just talk about the fats that we eat in oils and use terms that you've probably people have heard before. So there's monounsaturated fats, there's polyunsaturated fats, and there's saturated fats.
- [04:58]
B
Saturated fats bad.
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C
Right?
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B
I know that one.
- [05:01]
C
Saturated fats generally bad, depending on what food it comes in. But by and large, saturated fats are bad for you monounsaturated fats, which are the dominant fat. So these are not fats as much as fatty acids. And this is an important part of the story to understand what's going on here is that we're talking about fatty acids, which in the same way as amino acids, are the building blocks for proteins, fatty acids are the building blocks for fats in our bodies. And we do need fats to survive. We've got fats surrounding our cells to keep the integrity of our cells together.
- [05:34]
B
And our brains, really importantly.
- [05:36]
C
And communication between cells involves fats as well. So fats are important, and fatty acids are what they're made from. And fatty acids in this definition are defined chemically. I know I'm going to blind you with science here, but I'll blind the audience with science here. But when you talk about O omega 3s, omega 6s, these are different variations on the polyunsaturated fat. So saturated fats, the bonds that attach carbon to these fatty acid molecules, if it's just a single bond throughout the whole molecule, that's called a saturated fat. Sometimes there's a double bond there. And depending on whereabouts in the molecule it is near the beginning or near the end, it can be called an N3, in other words, an omega 3 fatty acid. Or towards the end, it could be an omega 6 fatty acid.
- [06:25]
B
Is that what the omegas mean?
- [06:26]
C
Yeah, it's the place on the molecule. And people have got it into their head that omega 6 fatty acids are bad for you and omega 3 fatty acids are good for you.
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B
Okay, so what I've heard a lot about in this space of people who sort of quoting research, quoting science with concerns around seed oils, is about the ratio of omega 3, which I think a lot of people have heard of, because it's in fish. And it's good for you, it's good for your brain. That's sort of the narrative around Omega 3 and Omega 6 and that perhaps we're eating a lot more Omega 6 compared to Omega 3 than we did in more traditional diets.
- [07:07]
C
Yeah. In many of these seed oils, not all of them, but in many of these seed oils, there's more Omega 6 than Omega 3. So you're talking about substance, for example, like linoleic acid as an omega 6, where alpha linoleic acid is an omega 3.
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B
Are you saying these as if they're household Names, Norman, like, where would I be finding linoleic acid?
- [07:27]
C
So you'll be finding linoleic acid in grapeseed oil in quite large amounts, canola, sunflower oil, in peanut oil, rice bran oil. They're all there. And it's much lower in olive oil, for example, although that's not a seed oil. So a scientist a few years ago decided that there was an important issue around the ratio in our diet of omega 6 to omega 3, and that somehow, if the ratio was high, in other words, you had Too much Omega 6 versus Omega 3 that was bad for you, caused an imbalance to your production of fats. So therefore, potentially increasing cholesterol, increasing inflammation, increasing oxidative stress in your body, and largely that's been debunked, is that the ratio of omega 6 to omega 3 fatty acids is really largely fallacious. Because what's known now is that omega 6 fatty acids are good for you. It's related to lower rates of heart disease, lower rates of inflammation, has not got an adverse effect on oxidative stress. And omega 3 fatty acids are good for you, too. And one critic of this ratio issue saying, is that you're dividing the good, in other words, omega 6, by the good omega 3, and it's really spurious, and that omega 6 fatty acids have been wrongly labeled as bad for you. They're not bad for you. There's almost no evidence for that. When you look at the large studies, omega 6 fatty acids are pretty good for you.
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B
So if they're good for you, then why are people like RFK saying that they're causing health harms?
- [09:01]
C
Because there are some writers based on not very much evidence, suggesting that these are poison and that they're causing major nutritional problems, in his case, in the American population, but elsewhere as well, and they're talking about the return to animal fats, which are high in saturated fats and are associated, amongst other things, with increasing inflammation, increase in oxidative stress, whereas these fatty acids aren't.
- [09:24]
B
I do want to talk about that, because, yeah, I see a lot of make oil tallow. Again, they're really big on beef tallow and lard, which are rendered forms of animal fats, which for sure have absolutely been part of human diets for a really, really long time. But as you say, we do know that those animal fats are really high saturated fats, and we absolutely don't live other parts of our lives like cave people did either.
- [09:48]
C
So you can't take this in isolation. So often they'll talk about the Amish And I think you and I have spoken about the Amish before in North America. So a group of people who, for religious reasons and cultural reasons, live a very traditional, pre industrial lifestyle. And when you analyze their diet, it's very high in animal fat. But they're living a pre industrial lifestyle. They're burning thousands of calories a day.
- [10:13]
B
Yeah, I can't remember the last time I built a barn. They seem to do it every day. It doesn't feel like a fair comparison.
- [10:19]
C
That's right. And when you're burning a large number of calories a day, your body is actually quite forgiving of what you eat. Second thing is, which is partly this Paleo fantasy, just remember life expectancy in the paleolithic was about 28. So just be careful what you wish for here.
- [10:37]
B
Yes.
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C
So when you take a monounsaturated fat, so lots of us are having olive oil, and olive oil, particularly extra virgin olive oil, is great for you. It's got polyphenols in it, it's got antioxidants, it's got bioactive substances, and it's got monounsaturated fats. In other words, there's only one bond that's double in these fats. And the story with olive oil and coronary heart disease is not so much that monounsaturated fats are fantastic for you, it's that they're neutral when it comes to your cholesterol. What you do when you cook with olive oil and have it in your food is that you're replacing saturated fat with olive oil. And it's that replacement that gives you most of the benefit when you're eating monounsaturated fats. On the other hand, when you take polyunsaturated fats like omega 6 and omega 3, remember, these are also what are called essential fatty acids. We don't make these fatty acids in our body, we need to take them in our diet. And by the way, if you don't take enough linoleic acid in your diet, you can actually suffer a linoleic acid deficiency, which can be a dermatological condition like itchy, scaly skin. So we need these substances in our diet. But what these polyunsaturated fatty acids do is they interfere with cholesterol metabolism and reduce the production particularly of LDL cholesterol, the nasty form of cholesterol. So they intervene in a healthy way in the cholesterol metabolism in our body, which monounsaturated fats don't, which means they have potentially added benefit.
- [12:09]
B
Okay. So I feel like one of the big pieces of the puzzle with why people don't like seed oil is its role in manufactured food. So ultra processed foods, specifically, often really high in calories, and often those calories are coming from seed oils because they're cheap to produce and they don't really have strong flavour a lot of the time. So they end up being the source of fat in those foods.
- [12:34]
C
And they're also heat stable, which means if you need heat to make those foods, they're going to be stable.
- [12:38]
B
So how much of the bad rap that seed oils are getting are actually because they're in ultra processed foods, rather than the seed oils themselves as being the villain?
- [12:46]
C
Well, the people who are complaining about seed oils and saying that they are poison are actually arguing from a metabolic point of view. They're saying they're bad wherever you get them from. And at least my reading of it, they're not really that focused on ultra processed foods. They're focused on these fatty acids themselves. I mean, to give you an example of how misleading it is, they're worried about this substance called arachidonic acid. And arachidonic acid is actually known to increase inflammation to some extent. And so they say, well, because linoleic acid is turned into arachidonic acid, that's why you get a problem with inflammation. But in fact, the proportion of linoleic acid that's turned into arachidonic acid is 0.12%. So it's insignificant compared to everything else linic acid does, or the other polyunsaturated fats do in your body. So they do argue in quite a sophisticated way against it, but using misleading biochemistry.
- [13:42]
B
Okay, so I feel like we've said a lot of really long names, we've talked about chemical bonds and whatnot. I haven't really heard any strong evidence against seed oils. Norman, is there something that I've missed here?
- [13:54]
C
Not that I can find. If you just look at the literature of large groups, groups of people, there haven't been very many clinical trials. But when you look at the epidemiological studies, when you look at the metabolic studies, the biochemistry studies in the lab, they all point in the same direction in terms of a beneficial effect on blood fats, on cholesterol, LDL, maybe even with some seed oils, on type 2 diabetes, and that may be an effect on LDL cholesterol. It's a fascinating study. So we have a bell for the Mediterranean diet.
- [14:24]
B
Bring a ding, ding.
- [14:26]
C
But we also, over the last year or so, on what's that rash. Have been talking about another phenomenon, pleiotropy.
- [14:34]
B
Oh, pleiotropy. I want, like a xylophone, I think.
- [14:37]
C
Yeah, we need another noise for pleiotropy.
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B
Like a.
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C
Where genes have two kind of roles in the body. And there's a recent study which suggests that the genes for type 2 diabetes and LDL cholesterol might be linked. And when you reduce LDL, you also reduce the risk of type 2 diabetes. And it's a genetic effect which could be. The link here is that these substances, these polyunsaturated fatty acids, reduce LDL and therefore reduce the risk of type 2 diabetes.
- [15:06]
B
So, to come back to Peter's question, the claim that he's heard from RFK and others is that people are being poisoned by seed oils. Animal fats would be a preferable alternative. Is this something that he should be worried about?
- [15:19]
C
No, if he's using seed oils responsibly, in other words, if he's using them for frying and frying judiciously and not going mad and filling up his calorie allowance with fried foods, it's fine. So it's the fried foods and the calories that you should be worried about far more. But you should not be reusing seed oils more than once. In other words, once you've cooked with them at high heat, you have to get rid of them responsibly because they can change chemically from repeated heated use, which makes me concerned because when I was a child, my mother had a chip pan on the stove the whole time and that oil was never changed.
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B
Oh, my God.
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C
Don't grow up in Glasgow.
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B
I do love the rebrand that you've managed to pull off here, Norman, by being a boy eating chips in Glasgow to being the ding ding diet toting health guru that you are today.
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C
Yeah, but just show me a French fry and I go back, I regress immediately.
- [16:19]
B
Oh, well, Peter, thank you so much for sending in your question. If you have a question, we love answering them, you can email us thatrashbc.net au which is also where you can send us any other thoughts. Doesn't have to be a question. Nayri has sent us in a story, Norman. Do you want to hear it?
- [16:33]
C
Yeah, I do.
- [16:34]
B
Well, this is in response to our episode about basically whether you need to actually bathe. After all, people love this. Quite a few people have written about this, but Ngairi wants to tell us about a historian of England whose name is Ruth Goodman, who learns in part by experimentation. And she did Some work on Tudor England and went a whole year without Washington, washing her body with water. But she used Tudor era methods of cleaning the body. So mainly wearing linen as the first layer next to the skin, changing those linens daily or at least a few times a week, and rubbing her skin with a dry cloth from time to time, washing her face, hands and feet with water and cloth because Tudor people thought that getting wet was dangerous, that it was how the infections might have entered the body. Anyway, this woman, Ruth Goodman, a whole year living like a Tudor, wearing her linens, living among people with 21st century expectations of body smells. Nobody ever noticed anything and she didn't notice much either.
- [17:33]
C
And has she got a control experiment in here?
- [17:36]
B
Actually, yes, now that you mention it. She did have a colleague who did another experiment. He washed daily with water but didn't change his shirt and he stank. So he was wearing a synthetic blend fabric as well, which they thought might also be a factor. So yeah, a couple of things you've got to take into consideration if you are going to not bathe.
- [17:55]
C
I knew there was a reason I was a fan of linen, but then.
- [17:58]
B
Ivan has messaged in saying that he and his family haven't had any soap.
- [18:02]
C
In the shower shop, in the shower.
- [18:03]
B
Shop, in a shower, had any soap in the shower for 30 plus years and no one has noticed. We change our clothes daily and I'm sure we don't smell that.
- [18:13]
C
Wishful thinking. I don't know.
- [18:14]
B
Okay, with respect, Ivan, I feel like I need a different nose to tell me that.
- [18:19]
C
Yes, that's right. Rather than self report, we also have.
- [18:22]
B
Claire and and Paul who both basically haven't washed their hair for years either.
- [18:29]
C
The podcast audience is just dirty.
- [18:34]
B
I love skipping a shower. It's one of my favourite things. I don't do it as in French.
- [18:38]
C
You've mentioned this before, which is why I'm glad you're in Brisbane and I'm in Sydney.
- [18:41]
B
Oh, you better believe I'm showering at the moment. It is so hot here. Can't get away with not showering at this time of year. Claire washes her hair maybe four times a year and has a full shower maybe six times a year. I wonder what prompts those six times times, whether they're like a frequency or whether it's a special occasion or after a special occasion.
- [19:00]
C
We'll just leave the world to speculate on that one. And it's taken away all my appetite for french fries, this little conversation.
- [19:09]
B
Well, if you have a shower story or lack thereof, that you want to tell us? Or if you have an oil anecdote, we want to hear it. That rashbc.netu see you next time.
- [19:19]
C
See you then, Sam.