These drugs reduce the amount of low-density lipoproteins, which transport cholesterol and triglycerides in the blood, or raise the concentration of high-density lipoproteins. The aim is to reduce the progression of atherosclerosis and therefore help prevent coronary heart disease. These drugs should be combined with a reduction of other risk factors for raised lipid concentrations, such as a high-fat diet, smoking and obesity. Lipid-regulating drugs include statins, fibrates, anion-exchange resins, and nicotinic acid, all of which may be used either singly or in combination, and under careful medical supervision.