Dietary Fat and Heart disease

Non communicable diseases (NCD) particularly cardiovascular diseases that lead to heart attacks and cardiac failures are a leading cause of morbidity and mortality. There has been an exponential increase in the incidence in India primarily due to changing lifestyles and unhealthy food habits. There is lot of emphasis on blood lipids and cholesterol levels, and these are frequently associated with our dietary fat intakes. Reducing fat intake is often a recommendation. This may not be entirely true since fat is an essential macronutrient for our body. It contributes 1/5 to 1/3^rd of our energy intake, essential for absorption of fat-soluble vitamins and many more cellular functions. The quantity and quality of fats consumed needs to be clearly defined to prevent adverse cardiac outcomes.

The Recommended Dietary Allowances (RDA) is, the total fat content of food does not exceed 30% of the calories (44-67 gms) of which not more than 20gms shall be saturated fats from meat, dairy fats and some cooking oils. Approximately 50% of the fat we consume comes from invisible or fat inherent to foods we eat e.g., meats, milk, nuts etc. And another half from visible fats like ghee, butter, and oils.

All fats are not the same, they vary depending on the proportion of fatty acids. The saturated and trans fatty acids (from partially hydrogenated vegetable oils) are the major risks while the unsaturated particularly the mono unsaturated and the omega 3 or n3 polyunsaturated (PUFA) are the ones that protect from cardiac problems.

In the western populations there is excessive consumption of saturated fats, but it may not be so in India based on the available survey data. It seems likely that our high n6 fatty acid intakes and low n3 is leading to a pro inflammatory state and along with excess body fat is contributing to lot of inflammation which is a factor that promotes atherosclerosis. Our high carbohydrate intake particularly the refined ones lead to higher triglycerides and an adverse lipid profile with high LDL cholesterol and Low HDL or good cholesterol. It is recommended that visible fat intake should be less than 25 gm of which less than a third from saturated fat and at least 2 to 3 g from n3 fats like fish, fish oils, soya, mustard or canola oils.

To get a mix of all fatty acids it is better to use at least two different types of oils for cooking purposes. Peanut oil, Rice bran, gingelly oil , mustard oil are traditionally used oils in India and all of them have a good amount of MUFA and PUFA. Ghee is a dairy fat with over 50% saturated fat and 30% mono unsaturated fat . If the quantity consumed is less than 10 g, there should be no adverse effects. Another native oil is coconut oil which by analysis has 90% saturated fat but almost 50% of the saturated fat is Lauric acid a medium chain saturated fat or MCT. Another oil that is rich in MCT is palm oil.

MCT’s are directly absorbed from the intestines and get metabolized in the liver to easily provide energy . They also promote burning up of calories and thus known to aid in weight loss. However, their effect on lipid profiles isn’t good in terms of elevated LDL levels. As in the case of ghee, coconut oil is also good provided they are consumed within the RDA limits for saturated fats.

Heart disease could be prevented through good lifestyles including physical activity, staying within ideal body weights, limiting refined carbs, using a combination of fats and oils and within the RDA. Traditional sources of fat are good for health if not overdone, oils with more monounsaturated or PUFA (Sunflower, safflower) oils with balance of omega 6 and 3 will minimize the risk. Exclusive n6 PUFA oils like sunflower or safflower are not heart friendly if they are not balanced with short chain n3 like alpha linolenic acid (ALNA)( 1 gm ALNA (n3)for every 5 g of Linoleic (n6).) Minimizing the inflammation in the body is as important as maintaining cholesterol or lipid profiles. Fish and algal food sources of long chain n3 fatty acids are good if acceptable to consumers. n3 fatty acid supplements have not been found beneficial in reducing cardiac catastrophes while food sources are better.