Scientists have found a new reason to ask people to start using butter, olive oil and coconut oil for cooking.

According to a latest research, cooking in vegetable oils such as sunflower and corn oil, releases toxic chemicals linked to a number of diseases, including cancer. The research seems to have challenged the earlier thought advice that oils rich in polyunsaturated fats are better for human health than saturated products.

The scientists at the De Montfort University Leicester (DMU) said that heating the vegetable oils releases a group of chemicals called aldehydes. This group of chemicals, has been linked to a number of illnesses, including dementia, cardiovascular disease and cancer.

During the study, the researchers gave goose fat, butter, lard, vegetable oil, sunflower oil, olive oil, corn oil and rapeseed oil to the participants. The leftovers from the used oil was collected and sent for an analysis.

The team found that upon heating, oils changed its molecular composition to produce aldehydes. While heating coconut oil and butter released about half and one millimole of aldehyde respectively, heating sunflower oil released more than five millimoles of the toxic aldehydes.

“People have been telling us how healthy polyunsaturates are in corn oil and sunflower oil,” said researcher Martin Grootveld, in an interview with The Telegraph. “But when you start messing around with them, subjecting them to high amounts of energy in the frying pan or the oven, they undergo a complex series of chemical reactions which results in the accumulation of large amounts of toxic compounds.”