Bad news for fish and chips: cooking with vegetable oils releases toxic chemical linked to cancer and dementia, warn researchers

Cooking with oil Fish and Chips

Vegetable oils, including sunflower, corn and soya bean oil, release toxic chemicals during cooking which have been linked to cancer and Alzheimer’s, experts have warned.

The oils, commonly believed to be a healthier option than the use of animal-based fats such as butter and lard, have been found to release high levels of harmful chemicals known as aldehydes during the cooking process.

Professor of bioanalytical chemistry and chemical pathology at DeMontfort University, Martin Grootveld, warns that food deep-fried in vegetable oils, such as a traditional meal of fish and chips, contains between 100 and 200 times more aldehydes than the World Health Organization’s recommended daily limit.

As well as increasing the risk of developing cancer and neurodegenerative conditions such as dementia, aldehydes have also been linked to heart disease, hypertension, inflammation, foetal malformations during pregnancy and impairments to mental health.

Professor John Stein, emeritus professor of neuroscience at Oxford University says the Omega 6 fatty acids contained in vegetable oils risk replacing beneficial Omega 3 acids that keep the brain healthy. He told The Telegraph: “If you eat too much corn oil or sunflower oil, the brain is absorbing too much Omega 6 and that effectively drives out Omega 3.”

"Human brain is changing"

Professor Stein describes a lack of Omega 3 as a “powerful contributory factor” to an increase in mental health issues and cautions: “the human brain is changing in a way that is as serious as climate change threatens to be”.

Olive Oil

Professor Grootveld, who undertook a series of experiments to measure aldehydic lipid oxidation products or LOPs and published the findings, adds: “This major problem has received scant or limited attention from the food industry and health researchers”, despite, he says, supporting evidence being available for many years. Olive oil, butter and lard were found to release much lower levels of aldehydes during the frying process with coconut oil deemed by researchers to be healthiest of all.

Current NHS advice suggests replacing saturated fats such as butter and lard with lower-fat alternatives including olive and vegetable oils, due to the strong association between saturated fat consumption and high cholesterol and heart disease.


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