Podcast: Should I Avoid Seed Oils?

Dr. David Majure: There’s been a movement towards replacing the seed oils in the fryers with saturated fatty acids in the fryers instead, so like the beef tallow and the lard. I am sad to say, but I don’t think that’s gonna make anybody healthier and quite to the contrary, it may make us sicker in general.

Courtney: Welcome to Health Matters, your weekly dose of the latest in health and wellness from NewYork-Presbyterian. I’m Courtney Allison.

 If you’re on social media, you’ve maybe heard an influencer advise you to swap the canola oil in your kitchen for butter instead. Sounds delicious! But science may tell us otherwise.

This week, we talk to Dr. David Majure, a cardiologist at NewYork-Presbyterian and Weill Cornell Medicine. He busts common misconceptions about seed oils and tells us how to keep a healthy balance of fats in our diet. 

So Dr. Majure, we’re here today to talk about seed oils, which there’s a lot of conversation about these days. What kinds of questions about seed oils come up in your practice?

Dr. David Majure: Well, you know, it’s really interesting, Courtney, I have to say, they don’t come up in practice all that often, and I find that a lot of of doctors are really not even aware of the ongoing conversation related to seed oils. But I do find that patients know about them, and when I ask them about them, I very frequently get the statement that, well, they’re bad for me. Right. And that has piqued my curiosity. And led to a lot of investigation into both the root of the controversy and where we currently are.

Courtney: Right, so in order to understand that controversy, let’s get some nutritional background on seed oils. What role do they play in our diet?

Dr. David Majure: Fats and fatty acids are critical for life. And they come in a lot of 

different forms. Fat is how we store fatty acids. And the fatty acids themselves are used for a variety of different processes. They’re a source of energy. So, for example, our heart primarily consumes fatty acids for its energy, but they also are important in the cell membranes. They’re important in cell signaling between cells and various metabolic processes.

Now, the fatty acids themselves can be divided into two primary categories. We have saturated fatty acids and unsaturated fatty acids. Saturated fatty acids comprise about 10% of the North American diet, and you find them in say, butter cows, milk meat. But it’s also found in plant oils as well. So palm oil and coconut oil. What makes them saturated is when all the carbon molecules are occupied by hydrogen. There’s no double bonds in the carbon molecules. So unsaturated fatty acids is when there’s at least one or more double bonds in the carbon.

Courtney: Got it, and I know that there are also different types of unsaturated fatty acids. We might see “monounsaturated fat” or “polyunsaturated fat” on our food labels. Can you break down the difference between these two?

Dr. David Majure: So monounsaturated fatty acids or MUFAs. I have one double bond and PUFAs or polyunsaturated fatty acids have more than one. So the prototypic MUFA is olive oil, which along with other compounds like phytosterols, clearly confers cardiovascular benefits, can be anti-inflammatory and can reduce the risk of cancer. And both the PUFAs and the MUFAs clearly reduce cholesterol levels as compared to saturated fatty acids. PUFAs can be subdivided further into Omega-3 and Omega-6 fatty acids.

Omega-6 fatty acids, along with Omega-3, are the essential fatty acids, meaning that we have to eat them. Omega-6 is also known as linoleic acid, and the issue is that in plant-based oils, we tend to get a lot of the linoleic acid and less of the Omega-3 or alpha linolenic acid.

But the linoleic acid is recognized to be metabolized to what’s called arachidonic acid, and that usually hangs out in the cell membranes. But, it itself is involved in the production of what are called pro-inflammatory eicosanoids. These are molecules that are involved in the inflammatory process, both the production of inflammation, but also the regulation of inflammation.

Courtney: Inflammation is something we hear a lot about. Could I trouble you for just a quick lay definition of inflammation?

Dr. David Majure: Inflammation is a state of perpetual burning of energy. That itself leads to damage of structures in the body, whether it be cells, blood vessels. When we get an infection, the inflammatory system is activated in order to fight the infections. So the inflammatory system is very important for our survival. But uncontrolled, it can lead to damage of cells, membranes, and propagation of disease.

We know that inflammation is part and parcel of both the development and the propagations of many of the conditions that we are currently dealing with, whether it be diabetes, high blood pressure, cardiovascular disease, cancer, Alzheimer’s, autoimmune disease.

And so the message from the people that would have us not eat seed oils is that, look, seed oils have a lot of linoleic acid in them. Linoleic acid can lead to arachidonic acid, which is linked to inflammation.

Courtney: And why are these fatty acids important to understand in the context of seed oils versus animal fats?

Dr. David Majure: So, there are two things to consider. One is the hypothesis by the anti-seed oil movement, that seed oils lead to inflammation. When we actually look and we have an awful lot of data to look at over time, there is no evidence that linoleic acid leads to meaningful increases in inflammation. 

And there are a couple of really interesting studies that look at this. So, for example, some of my favorite were done by David Iggman and colleagues in Sweden. And they did a number of studies where they tried to demonstrate whether or not polyunsaturated fatty acids as compared to saturated fatty acids would in fact lead to inflammation or would in fact lead to worse health outcomes.

They did a really fun experiment where they randomized people to consumption of muffins, and they bake these muffins with the exact same food substances except for in one arm they bake them with PUFA from safflower oil.  And they compared that to palm oil, which is a plant oil, but it’s a saturated fatty acid.

And so what did they find? So these people ate on average three muffins a day in both arms and weight increased over the seven week study by about 3.3 pounds inboth arms. And what did they find? Well, they found that the cholesterol levels significantly improved in the people that ate the safflower enriched muffins and significantly worsened in the people that were eating the saturated fatty acid or the palm oil muffins. And they also looked at inflammatory markers and they saw no difference or no activation of inflammatory markers in either arm.

Courtney: That’s so interesting. And have there been any studies that examine the relationship between seed oils and mortality?

Dr. David Majure: So there are two studies that were published just this year. There’s the Nurses Health Study, there’s the Health Professional Follow-up Study, and the Nurses Health Study II. So the Nurses Study was started in 1976 and the Health Professionals Follow-up Study was started in 1986.

And so we have hundreds of thousands of people in the US that we have been following, so we can actually see what happens, how well do they live, what sort of disease do they develop, and when they die. And then look for associations.

And they actually looked at the amount of butter consumption and they looked at the amount of plant-based oil and a particular seed oil consumption, and tried to see how they would fare. 

There was a 15% higher mortality with the highest level of intake of butter as compared to the lowest level of intake. And interestingly, there was a 16% lower mortality for the highest level of intake of total plant-based oils, as compared to the lowest level.

So that is to say the people that took in more butter tended to have worse mortality and the people that took in more plant-based oils had the lowest mortality. This was particularly true of the people that were eating canola, soybean, and olive oil. So, that would suggest that we do better with eating more of these, not less of them. 

Courtney: So those studies seem pretty clear. But I wonder, is there more to learn about seed oils?

Dr. David Majure: You know, one thing I think it’s important to recognize is that we are still learning an awful lot about this. And when we look at the overall population level data, we see overall that there’s benefits, but there are some examples where you can find potential signals of harm.

And so, for instance, recently here at Cornell in John Blenis’s Lab, he looked at the role of omega six fatty acids in breast cancer because there was a hypothesis that perhaps high levels of omega sixes or once again linoleic acid could potentially be related to tumor growth in breast cancer.

And they found that in the case of triple negative breast cancer – remember that occupies about 15 to 20% of breast cancers – that it could stimulate tumor growth, and that’s definitely something that needs to be explored. When you step back and look at the entire population, we’re not seeing increased risk of cancer with seed oils. We’re actually seeing the opposite.

Courtney: So beef, tallow and lard, what do we know about them and their impact on our health?

Dr. David Majure: They are high in saturated fatty acids, and the story here is really important. You have to kind of step back and think about what happened. In the sixties there was a movement to recognize that saturated fatty acids might be involved in the development of coronary artery disease because it was recognized that eating saturated fatty acids led to increased, bad cholesterol in the blood, and saturated fatty acids were discouraged from the foods.

The problem is what they were replaced with. So they were placed with carbohydrates and in particular, refined carbohydrates, added sugars, added salt, all the stuff that actually gets in the ultra processed foods. And actually led in part to the diabetes epidemic, the obesity epidemic and, and a lot of the problems that we currently face.

So rather than putting energy into eliminating seed oils, which could lead to overall harm, we should focus on the real culprit. And those are the ultra processed foods, which are high in calories, low in nutrients with highly refined grains, added sugars, salt and saturated fats, in particular, the trans fatty acids.

Courtney:  What makes a food an ultra-processed food?

Dr. David Majure:  It’s a great question because it honestly is something that can be quite confusing. Non-processed foods means I pick a carrot off the shelf and I eat it. Whereas ultra processed foods mean that the foods are produced with ingredients that you just couldn’t find in a typical kitchen. But that’s not to say that all ultra processed foods are bad for you.

So, for example, the block of tofu that I like to eat, that’s an ultra processed food. And the reason it is is because there’s an anti-caking agent that is added to it that categorize it as an ultra processed food, but that’s extremely healthy food.

Where the ultra processed foods often run into trouble is all these highly refined carbohydrates, but it’s also probably the preservatives that are added to it. They are calorie dense, but nutrient poor. And somewhere in there, perhaps they’re signaling to your brain that you’re just not getting enough. And so you’re getting less nutritious food, but you’re still hungry and so you’re eating more of it, and that then leads to overweight and obesity over time.

Courtney: So we spent a lot of time doing this already, but what are some myths you’d really like to bust around seed oils and seed oil alternatives?

Dr. David Majure: Right. So the general thing is to say that there is no strong evidence that seed oils are harmful and there is ample evidence to suggest that the commonly consumed seed oils, once again, canola and soy. Are potentially beneficial for us. Now, there has been a lot of talk about the impact of frying the seed oils and in particular leaving the seed oils in these deep fryers for a long period of time, reutilizing them and that possibly by heating them over and over again, you might create more pro-inflammatory molecules.

That has been difficult to prove in the lab. But honestly, what I would say to you is maybe you shouldn’t be eating a lot of fried foods to begin with because those foods tend to carry bad company and they tend to be more in line with ultra processed foods. And once again, there’s been a movement towards replacing the seed oils in the fryers, with saturated fatty acids in the fryers instead. So like the beef tallow and the lard. I am sad to say, but I don’t think that’s gonna make anybody healthier and quite to the contrary, it may make us sicker in general.

Much is made about the way that the seed oils are produced because they are produced in factories by extracting the oil from the seeds. Then they are exposed to a solvent, typically hexane, which helps to further extract the oil from the other compounds. And then they undergo a process of refining, and bleaching and deodorizing in order to make them stable, as pure as possible and free of any odors that might impact the way that they get integrated into the food that you cook. That has been linked through the idea of these being industrial and industrial in the setting of food is an automatic negative connotation.

But when we actually look at them, we’re not able to find the negative impacts of these oils in our foods. Anytime somebody claims that one thing is responsible for everything else in this case, chronic diseases, it’s probably false because life is always more complicated than that. The weight of the evidence vastly supports the positive benefits of these oils in our diet.

Courtney: Dr. Majure, thank you so much for joining us today to cut through the misinformation and the confusion around seed oils.

Dr. David Majure: Anytime. Happy to help Courtney.

Courtney: Our many thanks to Dr. David Majure. I’m Courtney Allison.

Health Matters is a production of NewYork-Presbyterian.

The views shared on this podcast solely reflect the expertise and experience of our guests. To learn more about Dr. Majure’s work with patients, check out the show notes.

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