Cholesterol is a substance that occurs naturally and is needed for your body to function properly. But a high level of cholesterol in the blood is a major risk factor for serious diseases such as coronary heart disease and stroke.
BLOOD CHOLESTEROL
Cholesterol is a soft, waxy substance found among the lipids (fats) in the bloodstream and in all of your body's cells. It is an important part of a healthy body because it is used to form cell membranes, some hormones, and other needed tissues. But a high level of cholesterol in the blood -- called hypercholesterolaemia -- is a major risk factor for coronary heart disease.
Cholesterol is also a form of fat found in egg yolks, meat, poultry, seafood and dairy products. Foods from plants -- such as fruits, vegetables, vegetable oils, grains, cereals, nuts and seeds -- may contain fat but not cholesterol.
Approximately 80 per cent of the cholesterol in your blood is manufactured by the liver. The remaining 20 per cent comes from the foods you eat. Although many foods may be labelled "cholesterol free" or "cholesterol reduced", the liver manufactures lipoproteins from all fats you consume, therefore it is important to concentrate more on reducing your total fat consumption, than on merely limited cholesterol consumption.
"Good" and "bad" cholesterol
Cholesterol and other fats can't dissolve in the blood, and so are transported to and from the cells in the form of lipoproteins. Lipoproteins are a combination of fat (lipids) and proteins. There are several kinds of lipoproteins. But the ones to be most concerned about are low-density lipoprotein (LDL) and high-density lipoprotein (HDL).
Low-density lipoprotein (LDL) is the major cholesterol carrier in the blood. Normal levels of LDL are essential for cell repair and growth, however high levels of LDL in the blood are associated with the development of atherosclerosis, and therefore coronary artery disease, heart attacks and strokes. This is why LDL cholesterol is often referred to as the "bad" cholesterol. Lower levels of LDL cholesterol reflect a lower risk of heart disease. Dietary treatment is advisable when LDL cholesterol levels are greater than 3.0 mmol/L (115 mg/dL) for adults 18 to 29, and
3.4 mmol/L (130 mg/dL) for adults 30 and over.
High-density lipoprotein or HDL has a higher protein-to-fat ratio than LDL and it makes up about one-third to one-fourth of the blood cholesterol. HDL is commonly referred to as the "good cholesterol" because it helps to carry excess LDL away from the walls of the blood vessels and back to the liver for excretion. Research suggests that high levels of HDL may protect the heart against atherosclerosis, and may even remove cholesterol from atherosclerotic plaques and slow down their growth. Dietary treatment is advisable when HDL cholesterol levels are less than 0.9
mmol/L (35 mg/dL) for adults 18 and over.
