bottles of oil

Seed oils are the latest food to attract the ire of social media influencers and “nutrition gurus”. These oils have been labelled "toxic" and accused of causing many health concerns such as heart disease, dementia, obesity and cancer. But let's chew the fat on seed oils and explore whether there is any truth to some of these claims.

What are seed oils?

Seed oil comes from the seed of a plant, such as canola, sunflower, soybean, linseed, sesame, rice bran and grapeseed. They’re commonly used in cooking and food manufacturing thanks to their chemical stability and high smoking points (the temperature at which an oil starts to burn and go rancid). 

What’s so controversial about seed oils?

Seed oils have a high omega-6 fatty acid content, and this is the main target of toxicity claims. Omega-6 fatty acids (such as linoleic acid and arachidonic acid) are types of polyunsaturated fat. They cannot be made by our bodies but they are needed for normal bodily function, so it’s essential we consume them in our diet. Despite being a valuable source of unsaturated fats and bioactive compounds, which are both regularly linked to good heart and brain health and diabetes prevention, we need to balance the amount we eat with another fatty acid – omega-3s. It’s not that omega-6 fatty acids are bad, but most people aren’t getting the ratio right. Unfortunately, some people have taken this to demonise seed oils and omega-6s altogether. 

What's more, some will have you believe that extracting oil from the seeds is hazardous and results in you consuming harmful chemicals. However, the extraction process has been a tried and tested method of producing oil for almost a century, and the research shows that it is perfectly safe. While trace amounts of solvents may remain in the oil after processing, these are perfectly safe and are not linked with poor health outcomesFSANZ – the food regulatory body in Australia and New Zealand – closely monitors any residual compounds that may be present in the oil.

Omega-6s vs Omega-3s

Let's momentarily shift our attention to omega-6's more popular cousin – the omega-3 fatty acid. Omega-3s, commonly seen as the darlings of the nutrition world, are anti-inflammatory while omega-6s are seen as pro-inflammatory. Omega-3 fatty acids are one type of fat regularly linked to many health benefits such as good heart health, cognition, insulin sensitivity and reduced inflammation. Omega-3s form part of the structure of our cell walls and are abundant in our eyes and brain. As these fatty acids are essential, we must consume them through foods like oily fish, chia seeds, walnuts and eggs. 

Some studies have linked omega-6s to inflammation in the body and others show increased intake may not have an effect. Some recent research shows no association between elevated omega-6 fatty acid levels and heart disease. This same study showed that higher levels of omega-6s in the bloodstream might even be protective against heart disease. This research highlights that nutrition is a complex science, and dietary recommendations should always be based on robust scientific evidence. 

Should you stop consuming seed oils and omega-6s?

The goal is to include a better balance of omega-3s and 6s. It is true that we are consuming too many omega-6s and not enough omega-3s. So, we should increase our dietary intake of salmon, mackerel, trout and other oily fish (the best sources of omega-3s). 

Because of their versatility, seed oils are often found in highly processed foods such as packaged baked goods, chips and chocolates. It goes without saying that there is merit in reducing the amount of highly processed foods in our diets.  But this has more to do with these foods being nutritionally poor and high in calories, sugar and salt, than their seed oil content. Eating foods in their whole and natural state is always the best option. Choosing to cook with seed oils will not cause ill health. The National Heart Foundation recommends using canola and other seed oils as affordable and nutritious cooking oils. 
While it's important to moderate our intake of the golden stuff, you can be assured that seed oils are perfectly safe, with many offering health benefits. The only thing toxic about seed oils is the negative press they are receiving.  

Joel Feren
Joel Feren

Known as The Nutrition Guy, Joel Feren is an Accredited Practising Dietitian and Accredited Nutritionist with a background in biomedical sciences. His speciality area is men’s health. Joel works alongside the media and some of the biggest food brands in the industry and is helping to shape the current food landscape and nutrition conversation.

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