As per various scientific evaluations, heating does not destroy vitamins completely, though frying can destroy vitamins (A, D and E) to some extent. The loss of vitamin A, D and E depends on the number of times the same oil is used for frying. There is an estimated loss of just about 20-25% of the vitamins originally added as fortificants. After four repeated frying, about 60% of the original levels of added vitamin are lost.
