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There’s a sizzling debate on social media over seed oils, with some people adamantly claiming they are unhealthy.
But new research, which expands on previous studies in this area, finds that they could reduce your risk of an early death.
Adding fuel to the social media controversy is Robert F. Kennedy Jr., secretary of the U.S. Department of Health and Human Services, who has also taken aim at seed oils.
In October, he posted on social media platform X, claiming that seed oils are poisoning Americans and are a driving cause of obesity.
Health experts continue to push back, saying seed oils are, in fact, not toxic. And they say it’s processed foods, not the oils themselves, that are the problem.
According to a vast majority of research, says Robert Bazinet, a professor of nutritional sciences at the University of Toronto, seed oils “aren’t as bad as everyone is saying that they are.”
And he points to an extensive new study as another example of research that says plant-based oils are linked to better long-term health. But before diving into that, let’s break down some of the controversy.
What are seed oils?
Often known as cooking or vegetable oils, seed oils come from the seeds of plants such as canola, corn, soybeans or sunflowers.
The oils have a high concentration of omega-6 fatty acids and low concentrations of omega-3 fatty acids. Both are polyunsaturated fats, which can help reduce bad cholesterol levels in blood — reducing the risk for heart disease and stroke.
In comparison, animal-based oils or fats have saturated fats, which can raise your bad cholesterol levels.
What are the social media claims?
In a TikTok video, a man stands in the middle of a grocery store aisle holding a bottle of canola oil and says that if you want to be healthier, you need to “completely remove seed oils” from your diet.
He’s not the only one. A quick search pulls up dozens of similar videos, one with several clips cut together of a person in grocery store aisles, grabbing food from shelves and naming the type of seed oil it contains.
All these posts come with a similar message: seed or plant-based oils are toxic and can cause varying health issues.
Some people on social media say that the chemical process of extracting the oil leaves hexane, an organic compound, behind in the final product. They worry it’s harmful to their health.
Another argument against seed oils: high levels of omega-6 fatty acids in the seed oils turn into harmful toxins that cause headaches, weight gain or inflammation when cooked.
How are they processed?
Commercial processing usually extracts oil from seeds by mechanically pressing them.
Whatever remains of the seeds is mixed with a chemical called hexane.
That mixture is heated to extract the remaining oil — usually what’s left behind is a combination of oil and hexane. That substance is distilled to remove the chemical.
The oil is processed before being packaged. Despite further treatment, small traces of hexane can sometimes stay in the final product — but research has said these levels are “well below the safety limits.”
In large amounts or with long-term exposure, hexane can cause health issues, including numbness in hands or feet, muscular weakness, blurred vision and fatigue.
Health Canada regulations say the allowed maximum residue limits of hexane in vegetable fats and oils is 10 parts per million.
What does research say?
A study published in the Journal of the American Medical Association (JAMA) this month expands on previous research, which finds that plant-based oils can possibly lower your risk of dying.
Researchers came to their conclusion after looking at questionnaire answers from more than 220,000 U.S. men and women over 33 years. During that time, participants shared information about their diet every four years.
Many trendy detox regimens and products promise to cleanse your system of toxins, reduce inflammation or help with weight loss. However, some doctors say detoxes tend to be ineffective, expensive and, in some cases, risky.
According to the study, people who consumed 2.5 to three teaspoons of butter every day increased their risk of dying from any cause by 15 per cent, compared to consuming little to no butter.
The more teaspoons of butter a person had per day, the more they were likely to die from cancer.
Meanwhile, those who consumed high amounts of plant-based oils, specifically canola, soybean and olive oil, had a lower risk of dying from any cause. And having higher amounts of canola oil and soybean oil seemed to lower the person’s risk of dying from cancer.
As well, it found that using two teaspoons of plant-based oil each day, instead of two teaspoons of butter, lowered the risk of death by 17 per cent.
Even though the study can’t prove a causal link, which is a common pitfall of nutrition research because it’s difficult to control other confounding factors, nutritional sciences professor Bazinet says it samples a large number of people over a prolonged period, which makes the findings more robust.
“I think this study should influence people’s behaviours,” he said.
“We’ve had a lot of pushback on the seed oils lately, and this is another piece of evidence showing that in fact, they’re protective.”
But he did still express some caution about the findings.
In particular, he pointed out that the people who consumed vegetable oils had slightly healthier lifestyles compared to the people who ate butter.
The study says that participants who had higher butter consumption also consumed more calories and had a higher body mass index. They were also more likely to actively smoke and less likely to exercise and use multivitamins.
Even though the researchers did their best to account for these differences, Bazinet said, they could have had a bigger impact on the person’s overall health compared to butter.
Other drawbacks listed in the research include people mistakenly reporting margarine as butter in the questionnaire.
“People often will lie or not fill out part of a form and they just forget what they’ve been eating, so those food frequency questionnaires, they’re not super accurate,” said Abby Langer, a registered dietitian in Toronto.
The study also says that a majority of participants were mostly white health-care professionals, which means the findings aren’t necessarily representative of everyone.
But what about the claims of toxic chemicals?
When asked about hexane remaining in the final product, Bazinet said the amount is “widely accepted to be trivial, if detectable at all.”
He added that the remaining levels are “well below any set safe limits.”
It’s because of the chemicals used in extracting seed oils during the heating process that some people point to cold-pressed oils, like avocado or olive oil, as being a better option.
Critics also say seed oils are often in processed foods, which can make you feel sluggish or gain weight. But Langer says this isn’t because of the seed oils.
Rather, she said, just eating a lot of processed foods can cause people to gain weight more rapidly — and that’s not necessarily because of the oils, but rather from the way the food was cooked or other ingredients in it.
As for concerns about inflammation in the body, the experts who spoke with CBC News say they aren’t aware of evidence that points to seed oils.
One 2017 analysis published in the journal Food and Function looked at 30 high quality studies related to inflammation. It found that consuming the omega-6 fatty acid, specifically linoleic acid — which is found in seed oils — doesn’t “have a significant effect on the blood concentrations of inflammatory markers.”
The one area that needs more research, said Bazinet, is how seed oils can change when they are reused and reheated, such as in restaurant deep fryers. He said the oils can break down and possibly become harmful, but notes that in these cases usually you can taste that the oil has gone bad.
So what should you do?
Having a balanced diet with “a variety of fats” is important, says Langer.
As for whether cold-pressed oils are better, Langer said that while they “may have more antioxidants in them … at the end of the day it is the totality of your diet that really matters.”
