Scientists have discovered that heating up vegetable oils leads to the release of high concentrations of chemicals called aldehydes, which have been linked to illnesses including cancer, heart disease and dementia.
Until recently, many experts recommended that we avoid olive oil when cooking and instead choose either vegetable or sunflower oil.
However, the new research found that sunflower oil and corn oil produced aldehydes at levels 20 times higher than recommended by the World Health Organisation. Olive oil, rapeseed oil, butter and goose fat produced far fewer harmful chemicals.
The researchers also identified two previously unknown aldehydes in the oil samples.
Contrary to traditional advice, he recommends people use light (non-extra virgin) olive oil for frying or cooking: "Firstly, because lower levels of these toxic compounds are generated, and secondly the compounds which are formed are less threatening to the human body."
Al Overton, buyer of gourmet oils for the organic supermarket chain Planet Organic, told The Telegraph that people are often confused about fats: "People are always asking me what to cook with. The simple answer is, keep a range of oils. Keep coconut or a similar saturated fat for heavy frying, olive and rapeseed oils for light frying and salads, and pumpkin and avocado oils for dressings and dips."
"More and more, we are realising that the food scientists who scared us away from cooking with certain fats got it wrong. It was our grannies – who cooked with goose fat or butter, ghee or coconut oil, depending on where they came from – who had the right idea."