A questionable nutrition bandwagon that many people have been jumping on.
Toxic, inflammatory, cause of chronic diseases are just some of the accusations.
Why all the hype? And, is it true?
What are seed oils?
Seed oils include rapeseed (canola), soybean, corn, sunflower oils.
What are they being accused of?
Seed oils are being accused of causing inflammation, heart disease, headaches, and obesity.
Are they actually toxic?
Firstly:
Seed oils contain omega-6 fatty acids, these are a type of polyunsaturated fat, which are essential in our diet as our bodies cannot make them on their own. Seed oils contain a lot of linoleic acid, and this is what is being accused of triggering inflammation. Linoleic acid plays a role in promoting skin health and maintaining cell membranes. The fatty acid itself doesn’t trigger inflammation. But, it is converted to another fat known as arachidonic acid. This fatty acid serves as a building block for some compounds which do play key roles in regulating inflammation.
So, if seed oils increase the risk of inflammation, and, as a result, other diseases that are linked to inflammation like cardiovascular disease and cancer, then they must be bad for us, right?
This seems to be a logical conclusion, but the science doesn’t back it up.
Only a small percentage of linoleic acid is converted to arachidonic acid in the body. A systematic review on linoleic acid consumption in adults found that high intakes of linoleic did not increase levels of arachidonic acid in the body.
There have been many studies carried out and research is yet to show that linoleic acid causes inflammation in humans, in fact some studies have shown that this particular fatty acid has been linked to reduced inflammation.
Secondly:
Another concern is the extraction process of the oils, with certain 'health gurus' claiming that the refined oils are full of chemicals and contain trans-fats. Heat is used to extract the oils and this process can create trans-fats.
You must be thinking that surely, they are bad for us.
The heating process is very brief, and yes, there are trace amounts of trans-fats. But the amounts are minimal. In the UK there are regulations when it comes to trans-fats in our food. The only concern is when seed oils are heated and reheated repeatedly e.g. in deep frying. This process can oxidise the oil which can lead to a build up of toxic compounds in the oil - however, this would be more of a concern for restaurants, rather than homes.
So, what's the verdict?
The fear mongering around seed oils is based on misunderstandings and misinformation. Consuming a variety of fat sources can offer a wide range of health benefits from lowering cholesterol to providing essential vitamins. No one single fat source needs to be avoided entirely. Yes, excessive consumption of any fat can be unhealthy - but moderate use of seed oils (especially in place of saturated fats) can contribute to overall wellbeing
You do not need to avoid seed oils and the evidence that we have at the moment shows us that seed oils are NOT detrimental to our health.
Published 6 February 2025
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