Is RFK Jr right about seed oils being dangerous? Asks our nutrition editor
Robert F. Kennedy Jr. – who's been nominated by President-elect Donald Trump to lead the Department of Health and Human Services – has some rather unorthodox views about medicine. He's a notorious anti-vaxxer, he's publicly contradicted the Centers for Disease Control and Prevention’s recommendations and he's a fan of raw milk, despite the Food and Drug Administration’s warning that drinking it is dangerous.
And now, he's claiming that seed oils are toxic – writing on X (formerly Twitter) that seed oils are ‘unknowingly poisoning’ Americans.
YouTubers and TikTokers alike are labelling seed oils as ‘toxic’, alleging they are ‘slowly killing you’ and contributing to rising rates of diabetes, obesity, and other chronic illnesses.
So, what’s behind the backlash against seed oils?
‘There is a growing narrative on social media claiming that seed oils are toxic, but these statements often lack scientific grounding and are factually incorrect,’ says Rhiannon Lambert, registered nutritionist, Sunday Times Bestseller and founder of Rhitrition and Rhitrition+.
‘The confusion stems from outdated theories about omega-6 fatty acids, which are abundant in seed oils,’ she explains. ‘Some argue that omega-6s promote inflammation in the body, however, more recent, high-quality studies now contradict this.
‘In fact, evidence suggests that moderate consumption of omega-6 fatty acids is associated with health benefits, including a reduced risk of cardiovascular disease.
‘While excessive intake of any food, including seed oils, may have negative health effects, the idea that they are inherently toxic is not supported by current scientific evidence.’
The claim that seed oils are ruining our health is clearly scientifically lacking. And even though Lambert points out that repeatedly heating seed oils to very high temperatures, such as in commercial deep-frying, may lead to the formation of harmful compounds, ‘this isn’t an issue when using seed oils in home cooking and therefore, there is no clear-cut scientific evidence that seed oils are toxic to us.’
To help clear up any confusion, we asked Lambert to explain what seed oils are, how seed oils affect our bodies and whether – if used in moderation – seed oils can be a valuable addition to a healthy lifestyle.
What are seed oils?
Seed oils are derived from the seeds of plants and are among the most commonly used oils in our diets today, explains Lambert.
Examples of seed oils include:
Rapeseed (also known as canola)
Sunflower
Soybean
Cottonseed
Corn
Grapeseed
Safflower oils
‘These oils are found in a wide range of products, from cooking oils to processed snacks, margarine, and even plant-based foods,’ says Lambert.
‘Many will recognise rapeseed oil as this is often an added ingredient in plant-based dairy alternatives. For this reason, many people believe plant-based drinks should be completely avoided if they contain rapeseed oil, but the truth is, the volume of rapeseed oil used in these drinks to improve the taste and texture, is minuscule compared to what you would need to consume before it became remotely “inflammatory”.
‘Seed oils are rich in unsaturated fats (the healthy fats), particularly omega-6 fatty acids like linoleic acid, which are essential for our health.’
What are the health concerns with seed oils?
As mentioned, the debate around seed oils often centres on their omega-6 fatty acid content, especially linoleic acid, which some argue could cause inflammation within the body (and therefore increase one’s risk of chronic diseases like diabetes or cardiovascular disease).
‘Importantly, this information hasn’t just been made up,’ confirms Lambert. ‘Linoleic acid can be converted into arachidonic acid, which is a compound that is involved in inflammatory processes, however, current research does not support the idea that consuming more linoleic acid increases inflammation.’
Wait... what is linoleic acid again? Linoleic acid is an essential fatty acid. This means your body needs it but can’t produce it. So, you need to get it through food. For example, from seed oils, nuts, meats and eggs.
In fact, scientific research, including one large study of nearly 70,000 participants, found that higher levels of linoleic acid are associated with a reduced risk of cardiovascular disease and type 2 diabetes.
‘It’s also important to note that many of the foods containing seed oils, like crisps, fast food, and packaged snacks, are unhealthy due to their high levels of refined carbohydrates, saturated fat, sugars, and sodium. It’s likely that these components – rather than the seed oils themselves – contribute to health risks,’ adds Lambert.
What are the benefits of seed oils?
When consumed in moderation as part of a balanced diet, seed oils do offer some nutritional benefits. ‘As mentioned, they are rich in unsaturated fats, particularly omega-6 fatty acids, which are essential for the body,’ says Lambert. ‘Omega-6 fats like linoleic acid are essential for brain function, skin and hair growth, bone health, metabolism and the reproductive systems.’
Additionally, research has shown that linoleic acid is associated with lower LDL cholesterol levels and a reduced risk of cardiovascular disease and type 2 diabetes. The review also found that higher levels of linoleic acid are linked with better glucose control.
‘Among seed oils, rapeseed oil stands out for its nutritional profile and is often considered the “better” of the seed oils,’ she says.
‘The reason for this is it contains a higher proportion of omega-3 fatty acids and less omega-6 compared to oils like soybean or sunflower oil. This results in a lower omega-6:3 ratio of 1:2.
‘Most experts agree that a 1:4 ratio or less is ideal for our health, which makes rapeseed oil a good option. To put this into perspective, sunflower oil has a ratio of 40:1, therefore clearly showing that sunflower oil has a significantly higher proportion of omega-6 than omega-3, making it the less favourable choice.
‘A lower omega-6:3 ratio helps to support anti-inflammatory processes and reduces the risk of chronic conditions like heart disease. Diets high in ultra-processed foods, often push this ratio towards an excess of omega-6 fats, as shown in the ratio of sunflower oil (a commonly used oil in the UK food industry).’
All this can seem a bit complicated, so all you really need to know is: that overconsumption of any type of fat (including seed oils), can have adverse effects, while moderate use of seed oils, particularly rapeseed oil, as part of a diverse diet can promote heart health, support brain function, and contribute to overall well-being, Lambert explains. ‘Pairing it with omega-3-rich foods like oily fish or flaxseeds can further optimise the balance of these essential fats.’
The bottom line
Ultimately, whether or not you decide to avoid seed oils is up to you. But current evidence suggests there are no issues with them.
If you want to switch seed oils for something else, then try virgin olive oil instead. But, as Lambert warns, ‘while extra virgin olive oil is often considered one of the healthiest oils due to its rich content of monounsaturated fats and antioxidants, it can be expensive’.
Seed oils, on the other hand, are both versatile and affordable, she says, pointing out that the key is to understand how these oils can fit into a balanced diet.
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