What do you mean by ‘vegetable oil rich in polyunsaturates’ ? Why is it recommended by physicians for persons suffering from high blood cholesterol or cardio vascular diseases ?
Polyunsaturated fatty acids are those which have more than one double bond. The vegetable oil having such polyunsaturate fatty acids is said to be rich in polyunsaturates.
Physicians recommend these to person's suffering from high blood pressure or cardio vascular diseases, because these lower the blood pressure and thus decreases the risks.