Benecol: What it is and how it works

THERE IS a key difference between Benecol and other low-cholesterol margarines such as Flora. Benecol is not only low in cholesterol itself, it is a cholesterol-lowering product, actively removing the substance from the gut.

This is significant because only one third of the cholesterol in the stomach comes from a person's diet. The other two thirds are supplied by the bile in the liver, which drains into the gut and is essential to the digestion. Much of this manufactured cholesterol is absorbed again, which explains why it is extremely difficult to reduce blood cholesterol levels by diet alone.

Scientists have known for decades that plant sterols - found within all plant cells - inhibit absorption of cholesterol from the intestine. The challenge has been to make them palatable - they have an unsavoury taste and texture - and to collect them in sufficient quantity, as they are present in most plants in very small amounts.

Raisio, a small Finnish paper-making company, found a way of converting the sterols into stanols and dissolving them in fat. Stanols are not absorbed by the body but pass straight through the intestine, taking the cholesterol with them. Exactly how they do this is not understood. As fat in the diet is digested, it is broken up into tiny droplets and the cholesterol has to get into these droplets in order to be absorbed with the fat. It is thought that the stanols inhibit this process.

Raisio claims that Benecol has no side-effects, although some studies have suggested that it lowers levels of carotenoids such as vitamin A. They say 200,000 people in Finland have eaten their product daily for three years without ill effects.

In Britain, heart disease and stroke is the major cause of death, claiming 90,000 lives a year among people under 65. Reducing cholesterol levels by 10 per cent is estimated to cut heart attack risk by between 20 and 50 per cent in those aged under 70.

The high price of Benecol will prevent it reaching a wide market, but competition could see prices fall. The ultimate goal would be a genetically engineered plant with high levels of sterols which would be cheap to extract. Theoretically, sterols could then be added to a range of foods, in the same way that folic acid is added to cereals.