Which among the following is a cardio-protective fatty acid? (DNB Jan 11)
|B|| Stearic acid |
|D||Omega-3 fatty acids|
PUFAs mainly the linoleic acid and α-linolenic acid (omega 3 fatty acid) have cardio-protective actions. In this question since linoleic is not given as an option so α-linolenic acid (omega 3 fatty acid) would be the next best option. Saturated fatty acids aggravate the risk of cardiovascular diseases by raising the LDL cholesterol levels.
a. It is now generally agreed that diet governs many situations favouring the onset of "heart disease", particularly coronary heart disease.
b. Of all the factors associated with CHD (e.g., plasma cholesterol, high blood pressure, cigarette smoking, lack of physical activity) plasma cholesterol has a very high statistical significance with the incidence of CHD. various other studies have supported the role of elevated blood levels of cholesterol and low density lipoproteins (LDL) in the development of atherosclerosis.
c. In addition trials of the effect of dietary changes on CHD have suggested that altering the fatty acid composition of the diet in favour of greater intake of polyunsaturated fatty acids (PUFA) and less intake of saturated fats, while restricting the intake of fat calories to less than 30 per cent of the total calories, may lower the risk that CHD will subsequently develop.
d. The cholesterol-raising effect is mainly produced by C12, C14 and C16 acids; stearic acid and fatty acids with less than 12 carbon atoms have a smaller effect on plasma cholesterol.
e. Dietary unsaturated fatty acids with two or more double bonds have been shown to lower plasma cholesterol. The mechanism of reduction of serum cholesterol by polyunsaturated fatty acids is not clear but includes reduced synthesis of VLDL. The proposition has often been made that a low HDl:LDL ratio favours the development of atheroma, thus favouring the onset of CHD.
f. Polyunsaturated fatty acids (e.g., linoleic and arachidonic acids) have an additional role, that is, to inhibit platelet aggregation and thus prevent thrombus formation.
a. Linoleic acid which is the main precursor of arachidonic acid is therefore regarded as the body's best bulwark against CHD. In short, essential fatty acids have in the last decade come to be regarded as of major importance in clinical nutrition.