Yam is a good source of Vitamin B6 which is needed by the body to break down a substance called homocysteine, which can damage blood vessels walls. High levels of homocysteine can also lead to heart attack despite having low levels of cholesterol. Thus, having a good supply of Vitamin B6 in the body is believed to reduce the risk of developing heart diseases. Potassium is an important component of cell and body fluids and controls heart rate and blood pressure by countering the hypertensive effects of sodium. Low intake of potassium-rich food can also lead to hypertension.