For decades, health professionals have been warning us how bad butter and lard was. However, previous study debunked this myth and discovered an even worse concern: vegetable oil is linked to cancer.

According to a study from the researchers of De Monfort University Leicester (DMU), sunflower oil and corn oil produce aldehydes when heated at levels 20 times higher than the standards set by the World Health Organization. Aldehydes are an organic compound usually related to various diseases such as cancer and dementia.

The study was based on a 20 years of research wherein Bioanalytical chemistry and Chemical pathology Professor Martin Grootveld of De Montfort University noted that frying fish with corn or sunflower oil had more toxic aldehydes than what is safe. He explained that oils undergo chemical reaction when heated-oils rich in polyunsaturated fats produce larger amounts of aldehydes while those rich in monounsaturated fats generate less, and saturated fats the least.

The toxic by-products have also been associated to heart diseases, cancer, malformations during pregnancies, inflammation, ulcers and elevated blood pressure. The government is still suggesting oils rich in polyunsaturated fats-and that apparently is the wrong advice.

With these findings, Grootveld counselled that people should start avoiding fried food or choose oil that will give off lower levels of these toxic products. Coconut oil is found to contain the least toxic with 90 percent healthy fats.

On the other hand, olive oil generates a lower concentration of toxins and produces other compounds which are less hazardous for human consumption; other oils such as rapeseed, butter, lard and even goose fat also generate smaller concentration of aldehydes. He also suggests removing excess oil in cooked food by using paper towels and keeping the oils in a cupboard and away from light. Oils should not be reused so that unhealthy side-products will not accumulate.