Is heating rapeseed oil bad for you? Can it be toxic or poisonous?
There has been a suggestion that cooking with vegetable oils at high temperatures releases aldehydes which have been linked to cancer and other diseases. The amount of aldehydes formed depends on the oil used, cooking method and oil temperature. When selecting an oil for cooking at high temperatures, such as frying, it is better to opt for one with a higher smoke point. This is the temperature at which the oil begins to break down, give off smoke and produce potentially harmful compounds. Typically refined oils have higher smoke points than unrefined oils (e.g. extra virgin or cold pressed), making refined oils, such as refined rapeseed oil, more suitable for cooking at high temperatures. Reheating of oils is also not recommended as it can result in lowering the smoke point of the oil each time.
Click here to compare the smoke points of different cooking oils.