Although these and other studies are highly persuasive about the role of homocysteine in heart disease and the protective effect of B vitamins, the theory hasn't yet been put to the definitive test with a randomised prospective trial. But even if such a study is finally conducted, in my view, homocysteine won't be found to be the only cause of arteriosclerosis.

There are two large exceptions to the homocysteine theory. First, homocysteine levels do not rise in early diabetes a situation which would be expected if homocysteine were the only cause of arteriosclerosis. Second, oddly enough, there is no correlation between high blood pressure and homocysteine levels, even though hypertension is an obvious risk factor for arterial heart disease.

These two exceptions suggest that development of coronary arterial disease is complicated, and not simply a matter of a single vitamin deficiency. For instance, a great deal of evidence shows that a deficiency of the mineral chromium plays a major role in the development of diabetes and and also hardened arteries.

Other evidence links magnesium deficiency with hypertension. These two factors may be every bit as important as homocysteine and B vitamins in developing heart disease.

The importance of chromium

Over many years, Biolab Medical Unit in London conducted a computer analysis of more than 40,000 patients, which showed that chromium levels fall markedly as we age. Chromium levels are lower in men than women from age 20 onward, and then fall dramatically between 40 and 65, the ages when coronary artery disease is known to increase. Patients with type 2 diabetes have lower levels of chromium in the blood than non diabetics. Giving diabetics supplements of chromium has been shown to improve glucose tolerance, decrease blood cholesterol and triglycerides and increase high density lipoprotein cholesterol the "good" cholesterol (Clin Chemistry, 1988; 34: 1525-6).

One Israeli study found that the aorta, or main coronary artery, of patients dying of coronary artery disease contained very little chromium, compared to a group of controls (Amer Heart J, 1980; 99: 604-6).

Supplementing with chromium has also been shown to increase glucose control in Type 2 diabetes mellitus (Diabetes, 1997; 46: 1786-91). Natural sugars and grains do contain adequate concentrations of chromium to help along the metabolism of these high carbohydrate foods. However, almost all chromium is removed during the refining process of most of the sugars sucrose or glucose which we eat. There's plenty of evidence showing that diets high in processed carbohydrates are deficient in chromium.

There's also evidence that societies which increase their intake of refined sugar intake have a very high incidence of coronary artery disease. Low chromium levels have been shown to be a major factor in the formation of high blood cholesterol levels in numerous laboratory studies.

Although animal studies cannot be applied to humans, and so should be viewed with suspicion, we have seen that giving chromium supplements will lower high blood cholesterol and highly processed foods low in chromium will result in high cholesterol levels. This suggests that high blood cholesterol does not itself cause coronary artery disease, but is simply a marker that something else like inadequate chromium intake 1 is awry.