Controlling Your Cholesterol
Cholesterol Levels can be Modified Through Diet and Exercise
Aug 27, 2008
Cholesterol is a substance which has acquired a bad name because increased levels are a risk factor for heart disease, but cholesterol is important to health. It is a component of cell membranes, and is a building block of steroid hormones such as testosterone and estrogen, and of vitamin D. Cholesterol is also used in the synthesis of bile salts, which are made in the liver, stored in the gall bladder, and are released into the small intestine to help absorb dietary fats.
Sources of Cholesterol
Only about 25% of total cholesterol comes from the diet; the other 75% is manufactured in the liver and other cells. Therefore, cholesterol levels are largely genetically determined, and though eating a healthy diet is important to maintaining cardiovascular health, there is a limit to how much cholesterol levels can be lowered through dietary modifications alone.
Cholesterol, Good and Bad
Cholesterol is an important component of cells, making up as much as 45% of the lipid in the membranes of certain cell types. Cholesterol is transported from the liver to the cells through the blood stream as a part of lipoprotein particles, or particles made up of lipids and proteins. Very low density lipoprotein particles (or VLDL) are made in the liver, and travel through the blood stream to deliver lipids to different tissues. As the lipids are removed, the particles become enriched in cholesterol, are now called low density lipoproteins (LDL), and deliver cholesterol to cells. LDL is one of the components measured when blood cholesterol is tested, and is the so-called "bad" cholesterol. When LDL levels are high, cholesterol can accumulate on the inner walls of arteries, forming plaques that impede blood flow. If clots block the arteries feeding the brain or heart, a stroke or heart attack can result.
High density lipoproteins (HDL) levels are also quantified when blood cholesterol levels are measured. HDL is known as the "good" cholesterol, because it seems to clear excess cholesterol from blood vessel walls, returning it to the liver. People with very low HDL levels, below about 40 mg/dL, are at increased risk for coronary artery disease, while levels above 60 mg/dL may protect against heart disease.
Changing Cholesterol Levels Through Lifestyle Modification
Avoiding heart disease involves controlling cholesterol levels, specifically lowing LDL and raising HDL to healthy levels. Lifestyle changes can have a substantial effect. Smoking and obesity reduce HDL, so quitting smoking and loosing excess weight can have a positive effect on HDL levels. Aerobic exercise also increases HDL levels. Dietary changes such as increasing the amount of plant-based foods, and avoiding saturated and trans fats, meats, cheese and eggs, can reduce LDL levels. Foods high in soluble fiber, such as oatmeal and bran, reduce the absorption of cholesterol in the diet. Lifestyle changes can reduce "bad" cholesterol by 20-40%. Combined with the increases in HDL that can be achieved through exercise and weight loss, this means that the risk of heart attack and stroke can be substantially reduced by lifestyle modifications.
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