Cholesterol is a waxy substance that is present in your blood. This is an essential substance for your body to build healthy cells. But high levels of this can put you at risk of heart disease. It can lead to fatty deposits in your blood vessels which restricts the flow of blood through your arteries. If these deposits break off and form a clot it can cause a heart attack or stroke. High cholesterol may be inherited. But more often than not it is the result of an unhealthy lifestyle. Many people have a family history of high cholesterol in