Move over cholesterol, you have had your moment of fame. Since the early 20th Century, cholesterol has taken the rap for causing heart disease and strokes.

Nowadays, most people assume that as long as they keep their cholesterol levels down, there is no cause for concern.

Yet studies have consistently shown that 80 per cent of people who die of advanced heart disease have normal cholesterol levels.

It seems that cholesterol isn't the only culprit when it comes to cardiovascular disease. A new villain has been found.

It is a natural substance called homocysteine, made by the body from the normal breakdown of dietary protein.

Homocysteine is a toxic substance and has the potential to cause considerable harm when it becomes elevated in the blood.

If so, it can damage the lining of the arteries which, when injured, attract bad LDL cholesterol.

As a result, blood clots form, increasing the risk of heart disease or strokes.

The homocysteine theory was originally developed in 1969 by Dr Kilmer McCully, an American pathologist. McCully also discovered that high homocysteine levels could be reduced by the intake of specific B vitamins.

As McCully's ideas were not mainstream and threatened the commercial interests of the food and pharmaceutical industries, he became a scientific outcast.

However, major human studies published during the Nineties confirmed his ideas and have been widely accepted.

When the body is optimally nourished, homocysteine is converted into harmless compounds.

But when certain nutritional deficiencies are present, conversion is impaired and homocysteine levels rise.

The most important nutrients required for conversion are the vitamins B6, B12 and folic acid.

Some individuals also need the B-complex substance betaine. There has been very little awareness in the UK about the significance of homocysteine.

Consequently, treat-ment for heart disease consists of cholesterol-lowering drugs and low-fat, low-cholesterol diets.

I asked Dr Stephen Terrass, Technical Director of Solgar Vitamin and Herbs UK and an expert on the effects of diet and nutrition, why the medical establishment has been so slow to catch on.

Dr Terrass explained that McCully's theories had been suppressed by the pro-cholesterol lobby in the US until the media started covering the issue in 1998 and it finally filtered down into public awareness.

Since then, homocysteine testing is, without doubt, saving countless American lives as well as a fortune in health-care costs.

As Newsweek reported: "It mayturn out that we can accommodate more with nickel-and-dime vitamin supplements than with drugs that cost hundreds more."

So, what can we learn? It is unproductive to look at just one set of data or one single dietary component. A healthy heart depends on many factors, such as the amount of fibre, vegetables, animal protein, fat and supplements you consume, your stress and exercise patterns and, not least, on your levels of homocysteine.

Nutritionists can advise on Cardiovascular Risk Profiles which measure the most important risk markers underlying cardiovascular health.