Seed oils have become one of the biggest targets of nutrition misinformation on TikTok, with viral posts warning that oils such as sunflower, rapeseed, soybean and corn oil are 'toxic', inflammatory or responsible for chronic disease.

But the science is considerably less dramatic.

Dietitians and nutrition experts have repeatedly pushed back against blanket claims that seed oils are harmful. While the overall quality of a person's diet matters, there is no good evidence that simply consuming moderate amounts of seed oils makes otherwise healthy people sick.

What Are Seed Oils?

Seed oils are vegetable oils extracted from seeds or plants. Common examples include sunflower, soybean, rapeseed, corn and safflower oils.

Many are rich in polyunsaturated fatty acids, including omega-6 fats such as linoleic acid. These are essential fats, meaning the body needs them but cannot produce them itself.

The Heart Foundation specifically mentions sunflower, soybean and canola oils among sources of unsaturated fats and recommends replacing saturated fats with unsaturated fats where possible. This directly contradicts the idea that all seed oils are inherently harmful.

Do Seed Oils Cause Inflammation?

One of the most persistent social-media claims is that omega-6 fatty acids in seed oils promote chronic inflammation.

The reality is more complicated. Omega-6 fats are involved in several biological processes, and the body needs them as part of a balanced diet. Simply labelling all omega-6 fats as 'inflammatory' ignores how these fats function in the body and how they are consumed within an overall diet.

More importantly, the health effects of dietary fat depend on what it replaces. Replacing foods high in saturated fat with unsaturated fats can improve the nutritional quality of the diet.

WHO recommends limiting saturated fat to less than 10% of total energy intake and replacing saturated and trans fats with polyunsaturated or monounsaturated fats from plant sources.

What About Heart Disease?

Another viral claim suggests seed oils increase the risk of heart disease. There is no basis for treating seed oils as a single category of heart-damaging foods. In fact, unsaturated vegetable oils can be part of a heart-healthy diet when used instead of fats high in saturated fat.

WHO recommends unsaturated oils such as soybean, sunflower, corn and canola oil as alternatives to butter, lard and other fats high in saturated fat. That does not mean people should consume unlimited amounts of oil. All fats are energy-dense, so portion size still matters.

Why Do Seed Oils Get Blamed?

Part of the confusion comes from the foods in which seed oils are often found.

Seed oils can be ingredients in biscuits, crisps, fried foods, takeaway meals and other highly processed products. Eating large amounts of these foods may contribute to an unhealthy diet, but that does not mean the oil itself is responsible for every potential health problem associated with the food.

A packet of crisps and a home-cooked meal containing a small amount of rapeseed oil should not be treated as nutritionally equivalent simply because both contain a seed oil.

WHO recommends diets based largely on minimally processed foods, including vegetables, fruit, whole grains, pulses and nuts, while limiting foods high in unhealthy fats, free sugars and salt.

Should You Avoid Seed Oils?

For most people, there is no need to eliminate seed oils simply because they are seed oils. Instead, focus on the overall dietary pattern. Use oils in sensible quantities, prioritise unsaturated fats and avoid excessive consumption of foods high in saturated and industrially produced trans fats.

It is also worth remembering that 'natural' does not automatically mean healthier, while a food ingredient sounding unfamiliar does not automatically make it dangerous.

Frequently Asked Questions

  • What are seed oils?
    Seed oils are vegetable oils extracted from seeds or plants, such as sunflower, soybean, rapeseed, corn, and safflower oils.
  • Do seed oils cause inflammation?
    Omega-6 fats in seed oils are involved in several biological processes and are needed as part of a balanced diet. Labelling them as 'inflammatory' ignores their function and consumption within an overall diet.
  • Do seed oils increase the risk of heart disease?
    There is no basis for treating seed oils as heart-damaging. Unsaturated vegetable oils can be part of a heart-healthy diet when used instead of fats high in saturated fat.
  • Should you avoid seed oils?
    For most people, there is no need to eliminate seed oils. Focus on the overall dietary pattern, use oils in sensible quantities, and prioritise unsaturated fats.
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