Advising to exercise caution against ‘repeated heating’ of vegetable oils or fats, ICMR (Indian Council of Medical Research) in its recently released guidelines has talked about the dangers of the practice. Repeatedly heating vegetable oils can lead to generation of toxic compounds that increase risk of cardiovascular diseases and cancer, said the medical research body. (Also read: ICMR says avoid milk tea; suggests when to drink tea and coffee, raises concern over excess consumption in new guideline)
Previous studies have also demonstrated how reheating of cooking oil can lead to release of toxic substances and also increase free radicals in the body causing inflammation and various chronic diseases.
ICMR along with National Institute of Nutrition released 17 new dietary guidelines for Indians across different age groups to help them make better food choices. The guidelines aim to provide evidence-based recommendations to help Indians make informed food choices to maintain good health and prevent malnutrition in all forms. In addition to dietary recommendations, the guidelines provide information on physical activity, hydration, healthy weight management, food safety and food labelling.
Repeated heating can cause cancer, heart disease
The guidelines noted that the practice of ‘reusing’ vegetable oils for cooking is very common, both at homes and in commercial establishments and explains how it may release harmful compounds that could lead to worrying health conditions.
“Repeated heating of vegetable oils/fat, results in oxidation of PUFA, leading to the generation of compounds which are harmful/toxic and may increase the risk of cardiovascular diseases and cancer,” says the report.
At high temperatures, some of the fats in oil change into trans fats. Trans fats are harmful fats that increase the risk of heart disease. When oils are reused, the amount of trans fats increases.
What ICMR says about reusing vegetable oils
Advising how vegetable oil can be reused, the apex body suggests filtering it for curry preparations and consuming such oil within a day or two.
“At household level, vegetable oil once used for frying, should be filtered and may be used for curry preparations but using the same oil for frying again should be avoided. Also, such oils should be consumed in a day or two. Storing ‘used’ oils for a long time should be avoided, as the rate of deterioration is high in such oils,” notes the report.
What experts say about repeated heating of vegetable oils
“Repeated heating of vegetable oils can lead to the formation of harmful compounds such as trans fats and acrylamide, which are linked to an increased risk of cancer. Additionally, reheating and reusing oil can result in the accumulation of free radicals and other toxic substances that contribute to inflammation, cardiovascular diseases, and liver damage. To avoid these risks, it is crucial to avoid using the same oil multiple times and instead use oils with high smoke points, such as avocado or safflower oil. Moreover, maintaining proper cooking temperatures and discarding oil after one use can significantly reduce the potential health hazards associated with reheated oils. Regularly consuming fresh, unprocessed oils is also advisable for better overall health,” says Dr Suparna Mukherjee, Charge of Clinical Nutrition, Narayana Health City, Bangalore.
“Reheating and reusing oil can have several negative health consequences beyond just cancer. As the oil breaks down with heat, it can release harmful toxins like aldehydes and become more acidic. These toxins can irritate the digestive system and potentially contribute to chronic diseases. Additionally, reheated oil can have a higher level of trans fats, which are linked to an increased risk of heart disease. The breakdown of the oil also generates free radicals, unstable molecules that damage cells and contribute to inflammation, a risk factor for many health problems. Finally, reheated oil can simply taste bad, imparting a burnt or rancid flavour to your food. While occasionally reusing oil likely won’t cause major problems, it’s best to minimize the practice and use fresh oil whenever possible for optimal health and flavour,” says Dr Mangesh P Kamath, Additional director, Medical Oncology, Fortis Hospital, Cunningham Road, Bangalore.
