What Recent Research Reveals About Seed Oils and Their Processing

The debate often starts with the oils’ high omega‑6 polyunsaturated fat content. Some experts argue that eating a lot of omega‑6 without enough omega‑3 could trigger inflammation, which might affect cardiovascular health.

Dr Louise Flanagan, head of research at the Stroke Association, says there is currently no strong evidence that seed oils are harmful.

A large U.S. study published in March 2025 followed more than 200,000 adults for about thirty years. Researchers found that people who ate more plant‑based oils had a lower risk of dying from cardiovascular disease.

The same analysis showed that higher intake of both seed‑derived oils and fruit‑derived oils was also linked to lower overall mortality and to fewer deaths from cancer.

How the oils are processed can change their health impact. Refined seed oils can oxidise when they are heated, especially if the same oil is reused. Oxidation creates free radicals and, under some conditions, trans fats.

Free radicals can damage cells and increase inflammation, while trans fats are known to raise the risk of heart disease. Refining also removes natural antioxidants such as polyphenols and vitamin E, making highly refined oils less nutrient‑rich than cold‑pressed versions.

BBC quoted dietitian Nichola Ludlam‑Raine, author of “How Not to Eat Ultra‑Processed,” saying that population studies have not shown harm from seed oils.

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