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Science

Diet and exercise

Cholesterol

A molecular model of a cholesterol molecule

Cholesterol is a substance found in the blood. It is made in the liver and is needed for healthy cell membranes. However, too much cholesterol in the blood increases the risk of heart disease, and of diseased arteries.

Good and bad cholesterol

The bloodstream transports cholesterol around the body attached to proteinsproteins: organic compounds made up of amino acid molecules. One of the three main food groups, proteins are needed by the body for cell growth and repair.. The combination of cholesterol and protein is called lipoprotein, and there are two types.

  1. Low-density lipoproteins - LDLs - carry cholesterol from the liver to the cells.
  2. High-density lipoproteins - HDLs - carry excess cholesterol back to the liver.

LDLs are often called 'bad' cholesterol because they lead to fat building up on artery walls, which causes heart disease. HDLs are often called ‘good’ cholesterol because they help to stop fat building up in the arteries.

Improving the balance

Watch

You may wish to view this BBC News report from 2006 about ‘statins’, a family of drugs that can improve high blood pressure and cholesterol levels.

A high proportion of HDLs to LDLs is good for a healthy heart. Monounsaturated and polyunsaturated oils - as found in vegetable oils - help to reduce cholesterol levels in the blood, and also increase the proportion of HDLs compared with LDLs. Check your understanding of such oils by looking at Vegetable oils.

There are also drugs that can improve high blood pressure and high cholesterol levels.

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