Q: How harmful or safe is butter and ghee for health, compared to margarine, mustard oil and refined oils like groundnut, sunflower and kardi (safflower) that are available in the market? Which oil or fat would you recommend for cooking?

SR, Calcutta

There are five varieties of fat available for cooking. Let us first examine how they affect our health:

a) Hydrogenated or partially hydrogenated fats: These are found in margarine and vanaspati and are used widely in processed foods and in many bakery products. These fats contain trans fatty acids (TFA) known to increase the LDL cholesterol in the blood, which when in excess or when oxidised, can get deposited in your arteries causing heart disease and strokes. Worse, these fats also reduce the good HDL cholesterol that cleans the arteries of their cholesterol deposits, thus helping prevent heart disease. TFA can also have an adverse effect on our cell membranes and lead to increased inflammation, decreased immunity and development of cancer.

b) The predominantly omega-6 containing polyunsaturated fats (PUFA). These are mostly found in sunflower, kardi, corn and sesame oils. They lower the total blood cholesterol, including the harmful LDL — an action that should potentially benefit the heart. However, this is offset by three adverse health effects of these oils — 1) they also lower the beneficial HDL; 2) they foster synthesis of pro-inflammatory variety of eicosanoid — chemicals that promote inflammation, blood clotting, constriction of blood vessels and growth of cancer cells; 3) they oxidise easily and cannot withstand heating. In high temperatures (as in frying), they break up, resulting in chemicals that have cancer-producing potential.

c) The saturated fats: These are found mostly in butter, ghee, coconut and palm oils. These fats increase the LDL and total blood cholesterol. If consumed in excess, these can trigger off blood clotting and thus increase the risk of heart disease. However, unlike the hydrogenated and omega-6 PUFA fats, these neither reduce the good HDL nor cause inflammation or reduce immunity.

d) Mono-unsaturated (MUFA) fats: These include mustard, olive, almond, groundnut and rapeseed oils. With the exception of groundnut (that also contains saturated fats), they all lower LDL without affecting the LDL levels and are beneficial for the heart. MUFA oils are mostly stable at high temperatures.

e) Omega-3 containing PUFA fats: These include rice bran, walnut, linseed and soyabean oils. These fats reduce both the LDL and HDL, but their real value lies in their ability to produce anti-inflammatory eicosanoids that help prevent heart disease, inflammatory disease and cancer.

Recommendations: Keeping in view the Indian cooking methods, two-thirds of your entire cooking oil need should be supplied by a MUFA oil like olive or mustard. The remaining one-third should be shared equally between omega-3 containing PUFA oil (rice bran or soyabean) and saturated fats (ghee or butter).