Fears about the potential negative health effects associated with the consumption of seed oils like rapeseed and sunflower oil – once a fringe diet concern associated with the niche paleo diet – are becoming increasingly common on social media platforms.
“No seed-oil” certifications, “seed-oil-free” restaurant apps, and product reformulations like Oatly’s ‘Super Basic’ – a version of its oat milk product with fewer ingredients (and no seed oil)– are finding a growing market as consumers are exposed to seed oil concerns.
However, many dietitians and nutritionists warn that the trend is a case of viral misinformation or exaggeration. National dietary guidelines also continue to promote sources of unsaturated fats as a healthier alternative to sources of saturated fats. Fi Global Insights evaluates the fears to separate facts from fiction.
“Seed oils are of the devil”, says Michael Knowles, the host of a conservative US Daily Wire show in a 2023 video titled “No, I Will NOT Stop Talking About Seed Oils”. Meanwhile, in an interview with Brain Health author Max Lugavere, popular podcaster Joe Rogan concludes that “if you’re cooking in grape seed oil, it’s a crime against nature”.
These statements, in all their intensity, are not very different from the content that many anti-seed oil influencers have created and shared on social media platforms like TikTok since around early 2021. According to a small but vocal group of health and fitness influencers, conditions such as Alzheimer’s, obesity, heart disease, sunburns, cancer, and above all, inflammation are caused by the rising consumption of seed oils.
Data from Google Trends shows that the message continues to spread. Search queries like “are seed oils bad?” were practically non-existent prior to mid-2021. Since then, the number of people looking for information has grown rapidly almost every month.
But why are oils derived from seeds – also called vegetable oils, a category that includes a wide range of popular products, from canola to cottonseed, flaxseed, and sunflower oil – suddenly considered so harmful? A range of scientific and not-so-scientific arguments related to nutrition and naturalness are common in the seed oil discourse.
Seed oils being unnatural, industrial, and unfit for a human diet is one common refrain. Paul Saladino, a doctor who goes by the moniker ‘Carnivore MD’ – one of the earliest and most frequently cited proponents of the theory – sums up this perspective on his website: “Also known as polyunsaturated fats or linoleic acid, [seed oils] are not a species-appropriate source of fat for humans.”
Many of the seed oils contained in packaged foods do undergo extensive processing, which can influence the nutritional quality of these products. Edible oils that have been treated in this way are sometimes referred to as RBD oils, which stands for three of the key stages that make raw oil more “user-friendly” for industrial manufacturers and home cooking applications: refining, bleaching, and deodorising.
There are scientific studies that show that such processes remove essential nutrients and can, in some cases, even introduce trans-fatty acids. Nonetheless, some studies suggest that concerns about adulteration of RBD oils with chemicals like hexane, a solvent, that are used in the refining process are overblown. Minor trace elements from chemical compounds can be found in oils like canola, but not at levels that would pose a danger to consumer health. And not all solvents pose the same risks; a new generation of solvents seems to be non-toxic and biodegradable.
Crucially, there are several ways of extracting oil from seeds like rapeseed, flaxseed, and sunflower that avoid chemical involvement and even the application of intense heat, including cold pressing and expeller pressing. By the same token, there are many non-seed oils like palm oil, olive oil, and coconut oil that can fall under the RBD oil category if treated with the same industrial processes.
Dr Emiliano Pena, a registered dietitian, neuroscientist, and senior content producer at Fi Global, told us:
“As with any food item, I would prefer lower processed seed oils compared to refined oils. From a nutritional point of view, RBDs – apart from potentially having less nutrients like vitamins and negligible traces of solvents (depending on the extraction method, as newer methods can be solvent free) – if handled properly should not pose a health risk on their own, unless they are consumed in high quantities.”
Another frequently cited concern that has some basis in scientific literature on nutrition is the link between omega-6 fats, which are relatively abundant in many types of seed oil, and inflammation. However, the science is a little more complicated than claims made by some opponents, like Seed Oil Rebellion – run by a husband-and-wife pair using the nicknames ‘Seed Oil Disrespecter’ and ‘Healthy Oil Respecter’.
One common claim is that all seed oils contain a lot of omega-6, which causes inflammation, in turn causing a litany of health concerns. But the evidence on omega-6 and inflammation and the link to seed oils of all kinds is more tenuous.
The ratio of omega-6 to omega-3 fat intake has indeed changed drastically in most Western countries in the last century, with a much higher intake of omega-6 compared to omega-3 fats. Some research suggests that getting the ratio closer to 1:1, rather than the current 20:1 could lower chronic inflammation.
“The omega-6 to omega-3 ratio – ideally 4:1 or lower – is what is recommended for optimal health … [but] both omega-6s and 3s are essential fatty acids needed for optimal health,” explains Dr Pena. “The conversion of omega-6s to inflammatory arachidonic acid, which is still needed for normal body function, seems to be very low, according to the current scientific evidence. They may increase inflammation by increasing oxidative stress in the body (free radicals) when oxidised, but there is currently not enough evidence to support this.”
In addition, the omega-6 to omega-3 ratio differs significantly between different types of seed oils. Canola oil – one of the seed oils often accused of being among the most “toxic” – has a ratio of 2:1; much closer to the optimal intake, and a lot higher than non-seed oils like those sourced from coconut, avocado, or olive.
Other health experts also note that both omega-6 and omega-3 fats have notable health benefits, with the Harvard Medical School citing evidence that omega-6 intake can lower heart attacks. It advises: “A low intake of omega-3 fats is not good for cardiovascular health, so bringing the two into better balance is a good idea. But don't do this by cutting back on healthy omega-6 fats. Instead, add some extra omega-3s.”
Seed oils form a broad category of different types and sources of fats. Those who are worried about the effect of industrial processing can look for seed oils that have undergone less processing. And consumers concerned about inflammation, who want to ensure they do not consume an excessive amount of omega-6, can find seed oils that contain a more even balance of omega-3 and omega-6 fats.
Dr Pena also notes that consumers can avoid seed oils altogether and increase omega-3 consumption through sources such as flaxseed, walnuts, oily fish, or algal oil: “Someone [who] does not want to use seed oils, [should] make sure to still eat the seeds to get those essential fatty acids – they also contain protein, fibre, vitamins and minerals – and above all, keep a good ratio between omega-6s and 3s and avoid overconsuming seed oils or other oils, as excess fat would still lead to increased energy intake, weight gain, etc.”
While avoiding excessive oil consumption of any kind is associated with a healthy diet, according to many experts, the current scientific evidence shows that seed oils do not pose a greater nutritional risk than other oils or fats – and can even offer some important health benefits.
