Keeping in mind evidence from the past as well as the latest scientific knowledge,current wisdom dictates the following criteria for identifying a healthy cooking oil:
The total fat intake should ideally be between 20 per cent and 35 per cent of the total calories.
The saturated fatty acid (SFA) content should be low,which means it should not exceed 8 to 10 per cent of the calories derived from fat sources.
The remaining calories (20 per cent) of the fat allowance should come from a mix of polyunsaturated fatty acids (Omega 3,Omega 6 ) and Monounsaturated fatty acids (Omega 9).
The ratio between PUFA and SFA should range between 0.8 and 1.
The ratio of Omega 6 to Omega 3 should be in the range of 4:1 to 10:1. Some of the western diets have ratios as high as 30:1 which are not quite desirable. There is data to suggest that such abnormal ratios could enhance the pro-inflammatory responses in the body.
The commercially produced trans fats have to be avoided,although some amount of naturally occurring trans fats that are present in meat and milk is acceptable.
Till now,nutritionists would emphasise the use of cooking oils based on these criteria. However,the task is much more complicated than what may be suggested by the above principles. It is not easy to single out one oil that meets all the above mentioned criteria. For instance,among all edible oils,olive oil has the highest content of MUFA but has no Omega.
Soy and mustard are high in Omega 3 but do not have the ideal Omega 6 to Omega 3 ratios. Therefore taking all things into account,the oils that emerge as better options are olive,mustard,peanut,sesame,rice bran and soy. Desi ghee or butter is no longer a no-no provided it is consumed only in limited amounts and is not used as the only source of fat in the diet.
Blending any two or three of these recommended oils could be an easy way to fulfill the varied requirement of fats in the body. Blended oils are now available commercially as well. Yet another way of incorporating the benefits of different oils is to use,say,olive oil for breakfast,sesame oil for lunch and mustard oil for dinner.
(Next week: Extraction matters too)