Ask a Nutritionist: Are Seed Oils Actually Bad for You?

Hi Charlotte, I keep hearing that seed oils are really bad for you. What is it that makes them so unhealthy? And why do you use seed oils in Huel when they’re really bad for you?

There are so many people out there saying seed oils cause inflammation, they cause cancer, they’re only okay if they’re cold pressed, that you need to consume butter and animal-fats instead. But is any of this true and where is it all coming from? Let’s break it down.

Seed oils are oils from seeds such as soybean, canola, sunflower and safflower. The idea that seed oils are bad for you comes from a few different angles that merge together.

A lot of highly processed unhealthy foods contain seed oils so a link is made there, another link is made between more seed oils being consumed in the last few decades and diseases caused by a poor diet. There are also studies which suggest that omega-6 fats (mainly the essential fatty acid linoleic acid) are harmful to health and anecdotal data from individuals who have said cutting out seed oils has improved their health. 

Let’s delve into these claims. The correlation between seed oils and poor health are just that, i.e. correlation, without the evidence to back them up. There’s a pretty good correlation between the number of people drowning in pools and the amount of films Nicholas Cage has appeared in, but that doesn’t mean we should go out and stop Nicholas Cage before we step in a pool again.

Animal studies and mechanistic data can help to explain why something might be happening. To do this large quantities of a substance are given to see an effect and then see what is causing it. 

That’s cool, but the large quantities are far above what a human would consume, and even when amounts are given that a human could consume, you need human studies to show the same thing happens. A few studies from 50 years ago seem to show this, however they lumped trans-fats with other fats, and seed oils do not contain these levels of trans-fats anymore. In fact there are regulations to limit how much trans-fats are permitted in the foods we eat.

So here’s the thing, we don’t have those human studies, we have the opposite. We have really good data showing that seed oils don’t cause negative health effects and – when consumed instead of high saturated fat alternatives such as butter – that they can actually improve health. 

For example, a review of human trials found that linoleic acid (a major fat found in seed oils) did not increase any inflammatory markers, while another review found that omega-6 fats had no effect on health, and finally a study following participants for over 22 years found similar results.

I think the issue is a lot of people that say seed oils are bad are just parroting what others are saying without looking at the evidence. Without naming names there are also influencers that purposely mislead to sway public opinion towards particular diets (and often products that they have to sell). At the end of the day the burden of proof is on these people to prove that seed oils are bad for health, not for scientists to prove otherwise even though this has been done.

Hopefully you’ve found this helpful. If you disagree or you would like to see a longer article, please let the team know or fill in the “Ask a Nutritionist” form using the link in the email.

TL;DR 

Studies have found that seed oils don’t cause negative health effects. Believe the science people, not what influencers are peddling on social media.

Written by: Dan Clarke, RNutr

Reviewed by: Charlotte Marie Werner, MS, RD, CDN