If you use social media, you may have heard: Seed oils are bad for your health—even toxic! Cooking oil from seeds causes everything from heart disease to inflammation to fatigue to bad skin—according to a section of Internet influencers. However, unlike the publications that present the usual ingredients, the scientific research body does not agree. Here’s how to understand the “scare” of health.
What are seed oils?
There are many different types of vegetable-based cooking oils, but when people talk about seed oils, they usually refer to a list of eight: Canola, corn, cottonseed, soybean, sunflower, safflower, grapeseed and rice bran oil. (Note that things like olive, avocado, and coconut oil are not on this list.) All eight of these oils contain fat and therefore fatty acids (an important group of nutrients). And many (though not all) of these seed oils are relatively high in omega-6 fatty acids.
A quick chemistry aside: fatty acids are the building blocks of triglycerides, or complete fat molecules. They are organic compounds made up of mostly carbon and hydrogen chains with an acid group at the end. In most fatty acids, every carbon except the terminal one has two hydrogens bonded to it. In unsaturated fats, some of the hydrogens are replaced by double bonds between adjacent carbons. Omega-6 fatty acids are unsaturated, and the first of those double bonds appears on the 6th carbon from the end—hence the name.
There are many types of omega-6 compounds, but a particular type, called linoleic acid, is at the center of much criticism against seed oil. Linoleic acid, also, is an important nutrient that our body needs. We can’t synthesize it, and we need it to support cellular health signals, function and immunity.
But opponents of the seed oil argue that we consume too much linoleic acid, which leads to the accumulation of products such as arachidonic acid, which they say causes inflammation and counteracts the benefits of consuming omega-3 fatty acids. . The net effect of all this, anti-seed oil advocates say, is a greater risk of diseases such as type 2 diabetes, heart disease and cancer.
A real straw
Inside the back against the seed oil there are a few kernels of truth. Eating too much fried and processed food is often harmful to your health. So if avoiding seed oil translates into eating fewer french fries and light pastries, you might feel better.
In addition, if you eat a typical western diet, you are probably not at risk of linoleic acid deficiency, and you are probably consuming more omega-6 fats than omega-3s. In recent decades the amount of linoleic acid in our diet has increased because many processed and restaurant foods are made from soybean, sunflower or safflower oil and animal foods now contain more soy, which translates into linoleic acid. in meat and milk. products, says Philip Calder, a nutrition scientist and professor at the University of Southampton in England. “Linoleic acid entered the food chain 50 to 60 years ago,” he says. Normal Science.
Additionally, Calder explains that there is “theoretical evidence” that linoleic acid can be partially converted to arachidonic acid, which is then converted into compounds associated with inflammation. In addition, omega-6s and omega-3s can compete for the same metabolic processes. All those biological processes are present in the human body.
However, here’s where things get stuck: that theoretical argument doesn’t agree with scientific thinking. “That doesn’t happen in real life,” says Guy H. Johnson, a nutrition scientist and assistant professor of food science and human nutrition at the University of Illinois at Urbana-Champaign. “If you have enough omega-3, the inflammatory environment is not increased by omega-6s.”
What the research shows
Calder agrees. “Many human studies show that there is no relationship between linoleic acid intake and inflammatory biomarkers, or that the relationship is the opposite of what you might think would happen. You see high linoleic acid and linoleic acid “higher arachidonic acid is associated with lower levels of inflammatory biomarkers,” he says. He co-authored a 2018 review study that evaluated the published literature on inflammation and omega-6s and concluded that.
“We found nothing to show that there is a harmful relationship between omega-6’s and inflammatory markers in humans,” he adds. A 2012 review by Johnson found something similar.
Many other review studies and meta-analyses have reached similar conclusions, and furthermore finding pluses where you might expect minuses. “Every time someone looks at blood levels of omega-6 and health outcomes — and we’ve done this several times with thousands of people… . Harris, a professor at the University of South Dakota’s Sanford School of Medicine and president of the Fatty Acid Research Institute.
Harris has co-authored numerous cohort studies as well as major review papers examining the effects of omega-6 fatty acids on health. In a 2017 meta-analysis, he and his co-authors found that omega-6 consumption actually lowers the risk of type 2 diabetes. In a 2020 review of 30 studies, Harris and colleagues and his colleagues concluded that higher levels of linoleic acid are associated with a reduced risk of heart disease.
In fact, high linoleic acid intake is associated with a lower risk of death from all causes including heart disease and cancer, according to another 2020 review that reviewed 38 different studies. I’m linking lessons – there’s a lot, but maybe you get the point.
The way fatty acids and metabolic processes occur in the body is complex. “There’s a different interaction between omega-6s, omega-3s, and other metabolites,” says Harris. The idea that omega-3s are good and omega-6s are bad is “not true and too simplistic,” he adds.
There are a number of positive, contradictory findings, say Harris and Calder. Including two, oft-cited papers published by lead author Christopher Ramsden, director of the Lipid Peroxidation Unit at the National Institute on Aging. In these studies, Ramsden discovered unpublished research from the late 1960s and early 70s in which two groups of people were fed a high-fat diet. of seeds and margarine have shown negative health effects.
However, there are significant limitations to these findings. For one, the study participants were fed oils much higher in omega-6 than are common in diets today, says Harris. Also, many of the solid margarines the study used may be high in saturated fat, which is understood to be harmful to human health, says Calder.
Another concern raised by seed oil skeptics is the use of hexane in production. “It’s true that hexane is used to extract vegetable oils regardless of where they come from,” says Johnson, who has written many health applications on various oils. But the product that consumers buy at the grocery store does not contain hexane at all. It’s gone,” he adds – removed during the process.
Overall, the overwhelming body of scientific evidence shows that cooking with omega-6 oils is safe and probably good for you.
So, what should you eat?
Based on the above, it may sound like you are starting to smoke safflower oil, but that is not the case. Since the western diet already includes plenty of omega-6, you’re probably covered. “We get a lot of omega-6. I’m not really advocating that people start supplementing their diet with omega-6,” says Harris. “But what I would say is that efforts to reduce intake while omega-6 will have a negative effect on health,” he adds. This is because less omega-6 means less protective benefits of linoleic acid, Harris explains.
It is also possible that those who want to exchange for seed oil may unwittingly end up exchanging for unhealthy alternatives. Often, influencers combine their disdain for seed oil with other health fads, such as promoting a “carnivore diet,” anti-sunscreen ideas, or sometimes three in one. This pile of misinformation will cause viewers to avoid sun protection and vegetables, while eating t-bone steaks and sticks of butter every day. There is nothing in the vast scientific research on human health and nutrition that suggests any of the above is a good idea.
Saturated fats may not be as harmful to heart health as once thought, but foods high in saturated fat and animal products can still raise your cholesterol risk. high and cardiovascular disease. Also, we already eat too much fat. In order to go from bulk to healthy following the modern western diet, Calder says omega-3s are the best choice, omega-6s come second, and fat most are at the bottom of the pyramid of things you should eat more of. of.
Harris, too, encourages people to try to eat more omega-3s, especially the kind found in seafood (seaweed and algae can provide a plant-based source for vegans and vegetarians). eat vegetables).
And in general, the best way to eat healthy food is probably what you would expect. A diet rich in fruits and vegetables, with lots of whole grains and fiber, is best, say Calder and Johnson. Johnson adds: “That’s what your mother told you. Walking more and eating less in general are probably also good ideas for most Americans, says Harris. “It’s not smooth, but it is.”
Finally, to stay positive, pay attention to the health claims you see online. Always remember that correlation does not equal causation, one person’s experience does not equal rigorous scientific study, and there is no simple solution for every health problem. “If it sounds too good or too easy to be true, it probably is,” says Johnson.
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