Cholesterol is a type of fat that is part of all animal cells. It is essential for many of the body metabolic processes, including hormone and bile production, and to help the body use vitamin D.

Cholesterol is more abundant in tissues which either synthesize more or have more abundant densely-packed membranes, for example, the liver, spinal cord and brain.

The liver is the main processing center for cholesterol. When we eat animal fats, the liver returns the cholesterol it can not use to our bloodstream and when there is too much cholesterol circulating in our bloodstream, it can build up into fatty deposits. These deposits cause the arteries to narrow and can eventually block the arteries completely, leading to heart disease and stroke.

Cholesterol is produced by the liver and it is also made by most cells in the body. It is carried around in the blood by lipoproteins. We need blood cholesterol because the body uses it to build the structure of cell membranes, to produce hormones like testosterone, adrenaline and estrogen and to aid the metabolism.

Types of Cholesterol

There are two types of cholesterol, good and bad, the difference between them is:

a. Low density lipoprotein (LDL) cholesterol called the bad cholesterol because it goes into the bloodstream and clogs up your arteries.

b. High density lipoprotein (HDL) cholesterol called the good cholesterol because it helps to take the bad cholesterol out of the bloodstream.

Cholesterol is transported towards peripheral tissues by the lipoproteins chylomicrons, very low density lipoproteins (VLDL) and low-density lipoproteins (LDL).

Risks associated with high triglycerides

According to the lipid hypothesis, abnormally high cholesterol levels (hypercholesterolemia), or more correctly, higher concentrations of LDL and lower concentrations of functional HDL are strongly associated with cardiovascular disease because these promote atheroma development in arteries (atherosclerosis). High cholesterol has also been linked to diabetes and high blood pressure.

Both heredity and diet have a significant influence on a person's LDL, HDL and total cholesterol levels. Evidence strongly indicates that high cholesterol levels can cause narrowing of the arteries (atherosclerosis), heart attacks, and strokes.

Cholesterol in the bile can crystallize to form gall stones that may block the bile ducts. Cholesterol count also rises during pregnancy.

However, in recent years, scientists have come to realise that to decide whether an individual's cholesterol levels are dangerous, these levels need to be considered in the light of the person's overall risk of heart disease.The higher the risk of heart disease (for example, a male smoker with high blood pressure and diabetes), the greater the need to get cholesterol levels down.

Cholesterol tests

Cholesterol testing is recommended as a screening test to be done on all adults at least once every five years.

Foods that contain cholesterol

The cholesterol in your diet comes mainly from the saturated fats found in animal products. All foods from animals contain some cholesterol. Foods from plants do not contain cholesterol. Other sources of dietary cholesterol are full fat dairy foods, eggs and some seafood.

Safe blood cholesterol levels

Health authorities recommend that cholesterol levels should be no higher than 5.5mmols per liter. Approximately 50 per cent of adult Australians have a blood cholesterol level above 5mmols per liter. This makes high blood cholesterol a major health concern in Australia.

How to lower high cholesterol

The best way to maintain healthy levels of cholesterol in your diet is to limit foods high in saturated fats. Try to avoid: Fatty meats , full fat dairy products, processed meats like salami and sausages, snack foods like chips, most takeaway foods, especially deep fried foods, cakes, biscuits and pastries.

However the most important thing you can do to reduce your cholesterol level is to maintain a healthy lifestyle. You should try to:

a. Limit the amount of cholesterol-rich foods you eat.

Increase the amount and variety of fresh fruit, vegetables and wholegrain foods you have each day.

b. Choose low or reduced fat milk, yoghurt and other dairy products or have added calcium soy drinks.

c. Choose lean meat (meat trimmed of fat or labeled as heart smart).

d. Limit fatty meats, including sausages and salami, and choose leaner sandwich meats like turkey breast or cooked lean chicken.

e. Have fish (fresh or canned) at least twice a week. Replace butter and dairy blends with polyunsaturated margarines.

f. Include foods in your diet that are rich in soluble fiber and healthy fats, such as nuts, legumes and seeds.

g. Limit cheese and ice cream to twice a week.

Some studies have suggested that eating oats and legumes may lower LDL cholesterol. Food components like saponins (found in chickpeas, alfalfa sprouts and other foods) and sulphur compounds (like allicin found in garlic and onions) may also have a positive effect on cholesterol levels.

Plant sterols can lower cholesterol levels,these are

found naturally in plant foods including sunflower and canola seeds, vegetable oils and (in smaller amounts) in nuts, legumes, cereals, fruit and vegetables. Some margarine has concentrated plant sterols added to it. Plant sterol enriched margarines may help to lower LDL cholesterol.

Treatment for high cholesterol

Treatment of high cholesterol is aimed at lowering the low-density lipoproteins (LDL) or bad cholesterol, lowering triglyceride levels, and increasing the high-density lipoproteins (HDL) or good cholesterol.

Treatment will be most effective if it also includes appropriate diet, weight loss (if necessary) and physical activity.

The first steps in treating high cholesterol levels are: Regular physical activity and healthy eating.

There are also some foods that may help to lower cholesterol levels, particularly garlic, soya, oats, corn and selenium-enriched cereals.

Cholesterol-lowering foods are not suitable for children under five years or for pregnant or breastfeeding mothers.

Medication :Statin drugs work by interfering with the cholesterol-producing mechanisms of the liver and by increasing the capacity of the liver to remove cholesterol from circulating blood. Statins can lower LDL cholesterol by as much as 60 percent, depending on the drug and dosage.