In the last few decades, the most important thing to know has been the total level of cholesterol. 240mg per decilitre (mg/dl) of blood was considered to be normal. But the Framingham study (the most important one of its kind) surprised the world by demonstrating that less than half of the victims of heart attacks had levels lower than this number. Today, it is desirable to have less than 200mg/dl or even 180mg/dl for the maximum reduction of risk.

Cholesterol needs sustenance - lipoproteins - to live in the blood. When those of low density, also called "bad" cholesterol or LDL, oxidise, they stick to the interior covering of the arteries which feed the heart, the brain and body tissues, reducing their diameter and providing the means of producing heart attacks, strokes, or a peripheral vascular illness.

According to current recommendations, people with a low risk of heart problems owe it to having levels of LDL of less than 130. People at risk, or with coronary illness already, must reduce this number even more, to lower than 100.

Statins are possibly the most revolutionary drug of recent years. They have transformed the treatment of high LDL cholesterol readings and are very efficient if they are combined with a healthy diet and regular exercise. However, they are not relevant to the last, and perhaps more important, preoccupation with cholesterol: the measurement of high density lipoproteins, "good" cholesterol or HDL.

The "good" cholesterol works like an unblocker of the tubes, taking the cholesterol from the walls of the arteries to the liver, from where it is eliminated. If the levels of LDL must be the lowest possible, how much greater are the levels of "unblocker", and that means that the total measurements of cholesterol are better than 200 mg/dl. In fact, low levels of HDL (less than 40mg for men and than 50 for women, who habitually have higher levels) are associated with a higher cardiovascular risk. Today, it is known that low levels of HDL mean more risk of heart disease and infarction than high levels of LDL. In fact, for each milligram extra of "good" cholesterol, the risk of suffering cardiovascular disease reduces by 3%.

In addition to helping the body to eliminate bad cholesterol, HDL protects in three distinct ways: it works as an anti-oxidant, it is a potent anti-inflammatory and it has anti-thrombosis properties which get rid of blood clots obstructing the arteries which result in angina, heart attacks and thrombosis.

The necessity of creating new medicines capable of increasing the levels of HDL is one of the principal objectives of the pharmaceutical industry even though statins are already increasing levels by between 5 and 10%. Existing medicines which most help in raising these levels are those which contain niacin. These drugs raise HDL amounts by between 15 and 30%, and are especially useful for increasing the bigger particles, which are the most effective at "cleaning" the arteries. Other drugs used are fibrates, frequently employed to reduce the levels of triglycerides, other fats which deteriorate the arteries, and which increase HDL by between 10 and 20%. In reality, many doctors prescribe statins combined with niacin or fibrates to increase these levels, but it is not a good solution because the combination of statins-niacin can provoke liver problems, and of statins-fibrates significantly increase the risk of muscular damage.

In our next article we'll look at how to manage cholesterol without the use of drugs.