Traditional Indian cooking oils such as mustard oil, coconut oil, and ghee are the healthiest for cooking, say experts.
Cooking oil is subjected to very high temperatures for deep frying and stir frying.
"Hence, Indians need to cook in oils which are stable even at high temperatures and do not break down into harmful components like free radicals, transfats, malondialdehyde (MDA), which not only put individuals at risk of heart diseases, but some of the components may potentially be carcinogenic," said Dr SC Manchanda, one of the authors of the paper and senior consultant in the department of cardiology at Sir Ganga Ram Hospital.
‘Cooking oil at high temperatures can destroy several antioxidants such as vitamin E and beta-carotene and also produces toxic compounds.’
Refined oils, which are readily available at grocery stores are a strict no-no. Oil is extracted from the seeds by the process of refining, mechanical and chemical processes.
They are then heated repeatedly at high temperatures of up to 270°C for deodorization.
"These high temperatures result in loss of antioxidants and produce all free radicals and transfat, both of which are harmful to the body," said Dr Manchanda.
Four things should be kept in mind while purchasing oil - low saturated fat, should contain omega-3 fatty acid, non-refined, and have no trans-fat.
The best oil to buy is non-refined mustard oil, non-refined canola oil, ghee, soybean oil, and a combination of canola and flaxseed oil.
"The important thing to remember is that repeated heating of the same oil must be avoided. It just exaggerates the harmful effects," said Dr Manchanda, quoting an Indian study, which found high levels of transfat in samples of oil collected from halwais who used the same oil for repeated frying.
The article is published in the Indian Heart Journal.