The controversial topic of seed oils – healthy or harmful?

You can find seed oils such as sunflower oil, soybean oil and canola oil in many everyday foods. These include salad dressings, sauces and snacks, ready meals, bakery products and even nuts.

Despite the fact that many scientists believe they have health benefits when consumed in moderation, an increasing number of critics claim they can fuel inflammation, diseases and even sunburn. What is the truth about seed oils, given that there are so many conflicting opinions on social media, in nutrition circles and across studies?

Why is seed oil so controversial?

The seeds are used to make vegetable oils, such as canola, corn, sunflower, and soybean oils. They are often used to cook and they’re common in ultra processed foods (UPFs). In recent years, their reputation has suffered.

Paul Saladino, MDA well-known critic for seed oils, claims that processed foods, sugars, and seed oils do not belong in the human food supply. “In my opinion, seed oils or oils made from plant seeds, such as canola and sunflower oils, are the worst offenders.

They are also called polyunsaturated fatty acids or linoleic Acid. We consume an enormous amount of these fats. You can get them from processed foods, seed oils and “healthy” seeds and nuts, as well as chicken and pork, which store the fat in their bodies and pass it to us.

As excess linoleic acids accumulate in the body, they “break” fat cell membranes and cause them to expand and balloon. This causes fat to be released. These free fatty acids cause insulin resistance and DNA damage in peripheral muscles.

In the past, our ancestors ate very little linoleic and today’s hunter-gatherers like Hadzas and Maasais consume just 2-3%. Meanwhile, many people are consuming up to 20% of their calories from this bullsh*t.

“I hope that the world will soon wake up to the fact that excess linoleic acids are the main cause of chronic diseases.”

US presidential candidate RFK Jr. has expressed concern as well, claiming that seed oils “are associated with all sorts of very serious diseases including body-wide inflammatory conditions” and are “one the most unhealthy foods we have.” (Citated by The Diary of a CEO.)

Omega-6 fatty acid is a major concern, especially linoleic acids found in large amounts in seed oil. Do these claims match up with the evidence?

What scientists have to say about the relationship between seed oils and inflammation

Omega-6s are often blamed for chronic inflammation.

Dariush Mozaffarian from Tufts University says, “New research shows omega-6 fatty acids produce unique natural molecules such as lipoxins which have powerful anti-inflammatory properties in the body.”BBC).

Christopher Gardner, who is a nutritionist at Stanford University, rejects this idea as well. He told the newspaper that “this argument is not supported” by rigorous clinical trials. BBC. “If anything, it’s shown to be anti-inflammatory… levels of inflammatory molecules actually reduce.”

In a large meta-analysis published in 2019, it was found that those with higher blood levels of linoleic acids had a 7% lower risk of heart disease. Matti Markus, a researcher, says: “Linoleic Acid is beneficial for heart health.” [acid] might improve cholesterol… and also improve glucose metabolism, which reduces the risk of type 2 diabetes”

Does seed oil make you more susceptible sunburnt?

Some online sources claim seed oils increase the risk of sunburns and skin damage.

One article states: “UV rays cannot initiate lipid peroxidation without a catalyst, which is seed oil… You can think of UV rays as the match, and seed oils as the gasoline” (Ifixhearts.com).

This theory is based around the oxidation polyunsaturated oils in skin exposed to sunlight. There is no peer reviewed human research that confirms this link.

Harvard dietitian Alison Kane recommends not overreacting: “Using a few tablespoons to sauté vegetables or in a salad dressing is a healthy option,” she told Harvard Health.

What about seed oils and cancer?

Some studies have examined a possible relationship between omega-6 consumption and cancer, especially triple-negative breast cancer (TNBC).

The 2024 Study published by Nature Linoleic acid may promote tumour growth among TNBCs, an aggressive subtype. Lead researcher Nikolaos Kourouros said, “TNBC appears to respond most to omega-6-linoleic acids.”BBC).

Seed oils and animal fats

Some campaigners want to return to the traditional fats, such as beef tallow and butter. RFK Jr. sells T-shirts saying: “Make Frying Oil Tallow Again.”

A meta-analysis of 42 research studies concluded that seed oils reduce cholesterol and inflammation better than saturated fats.

Alternative health voices like Carnivore Aurelius Some people believe that seed oils can be harmful. In a widely-read blog post, he wrote: “Eating oil seeds is like playing Russian roulette with a fully-loaded gun”.

He focuses on the following:

• Energy loss and inflammation are caused by mitochondrial damage due to linoleic-acid disrupting cardiolipins membranes.
• The formation of toxic breakdown products such as 4-HNE and MDA during oxidation is linked to cancers, Alzheimer’s and obesity.
• Accumulation in body fat, with linoleic acid now making up over 20 per cent of fat stores in modern humans, compared to 2–3 per cent in traditional societies.
• It is claimed that “PUFAs, like tallow or butter, are the primary dietary factor of chronic diseases today.”

He also refers to the Sydney Heart StudyResearchers have pointed out that the oils in this study were partially hydrogenated and contained trans fats, which are now limited or banned in many countries. Researchers have however pointed out that the oils studied in that study contained partially hydrogenated fats and trans fats which are now banned or limited in many countries.

Is the problem with ultra-processed products?

Experts say the issue might not be the oils themselves – but the foods they appear in.

Jason Ewoldt of the Mayo Clinic explains: “The seed oil is not the likely driver for negative health effects… Processed foods also tend to have higher levels of refined carbohydrates, salt and sugar”

Prof Mozaffarian agrees: “The dangers arise from too much starch, sugar, and salt, loss of natural intact food structure, and dozens… of artificial additives.”

What is the verdict on seed oil?

The debate on seed oils is not likely to be resolved anytime soon. While early lab research has raised valid questions – particularly about specific cancers and oxidation – most large-scale, peer-reviewed studies suggest that seed oils, in moderation, are not harmful, and may in fact offer several heart health benefits.

Critics point out that more human trials of high quality and long-term duration are needed to better understand chronic diseases, as well as the growing consumption of seed oils.

Were we wrong to blame seed oils for the broader problems in diet? Evidence is still developing.

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