Are consumers really being “unknowingly poisoned” by seed oils?

Seed oils have been used in the production of foods and beverages, and sold directly to consumers, for decades.

And during that time, there has been little question about the way in which they’re produced or their potential health impacts. Until four years ago, when their reputation took a rapid and very public nosedive, leading to a major backlash.

So how did this backlash start, and are the rumours true?

We look at the reasons behind the hate and discover if seed oils really are unhealthy.

How did the backlash against seed oils start?

It appears the controversy surrounding seed oils can be traced back to one man – Paul Saladino. The doctor, and advocate of the carnivore diet, was interviewed by Joe Rogan on his hugely popular podcast, The Joe Rogan Experience, in 2020. During the discussion, Saladino made several claims about the negative health effects of vegetable and seed oils. The backlash against seed oils had begun, and it grew, fast.

And it appears there are many who are keen to throw fuel on the raging fire, with none other than Robert F Kennedy Junior, joining the fray. President Elect, Donald Trump’s, nominee for US Health and Human Services Secretary, recently claimed on X that consumers are being “unknowingly poisoned” by seed oils.

So, are Paul Saladino, RFK Junior and the many others, who believe as they do, right? Are seed oils unhealthy?

Are seed oils unhealthy?

The short answer to this question appears to be no.

“Despite claims of toxicity, seed oils are largely safe and beneficial in moderation,” says Dr Raysa El Zein, nutrition and dementia researcher at the University of Westminster. “The refining process eliminates the most harmful substances, although it also reduces beneficial antioxidants.”

But few subjects are that straightforward, and based on the strength of consumer backlash, this one certainly requires further examination. So, are there downsides to seed oils?

Seed oils, such as sunflower, rapeseed, corn, and grapeseed, are extracted from plant seeds using a very high heat, chemical solvents, and intense pressure. After extraction, the oils undergo further refining to improve stability and extend shelf life. And while these processes give the product a longer shelf life and stabilise it so it doesn’t burn at high temperatures, they also have some downsides. These downsides include the reduction of beneficial compounds like antioxidants, polyphenols, and phospholipids.

But while these downsides lessen the positive health outcomes of seed oils, they don’t actively create negative health outcomes.

Another major negative associated with seed oils is the claim that they contain toxins. However, most of these compounds, such as pollutants and heavy metals, are removed during refining.

“The amount that is left is too small to cause humans any harm,” says Dr Zein.

Though there is one major area, which is cause for concern amongst researchers and nutritionists, and that’s in the reuse of seed oils.

“The main issue with these oils is that some fast-food outlets reuse them to cut costs,” says Dr Zein. “Once reused and reheated, trans fats, which increase ‘bad cholesterol’ and decrease ‘good cholesterol’, can form in the oil. However, most health and safety regulations ban the reuse of oils in food establishments.”

And connected to this, the real problem could be in the types of foods they’re being used in, rather than the oils themselves.

“The main issue with seed oils is that they are mostly found in highly processed food and fast food,” says Dr Zein. “Reducing the intake of ultra-processed food, whether made with seed oils or not, would have more health benefits than simply cutting down on seed oil. A lot of these foods are high in refined sugar, trans fats, and salt, which do more damage to health than seed oils.”

What are the benefits of seed oils?

Despite the bad press seed oils are receiving, they do offer some significant benefits, including acting as a rich source of omega-6 fatty acids.

“According to decades of rigorous research, these unsaturated fatty acids have many health benefits. They are linked to reduced risk of heart disease and improvements in cholesterol levels,” says Dr Zein.

Though this should be approached with caution, as Omega-6 can lead to health issues if consumed in high quantities, leading to a condition called, overnutrition.

“Omega-6 can increase the risk of inflammation throughout the body,” says Dr Zein. “Inflammation is linked to many chronic diseases, including heart disease and diabetes.”

And while fats are an essential part of a healthy diet, helping the body with the absorption of fat-soluble vitamins (A, D, E, and K), the intake of all oils should be restricted. And that includes so-called ‘good fats’, such as those found in olive oil, avocados and nuts.

“While seed oils are not toxic, fat intake should be moderated in any diet to maintain good health,” says Dr Zein. “A diet with some seed oil will not cause ill health. Seed oils also do not cause obesity, as some people are claiming. Obesity is linked to multiple factors beyond the type of oil being consumed. There is a stronger association between obesity and the amount rather than the type of oil consumed.”