Homocysteine and Heart Disease

Dateline: 12/20/98

Homocysteine (Hcy) is another protein that is in the news. It is a breakdown product of one of the essential amino-acids, methionine. High homocysteine levels have been associated with heart disease - a discovery made when a researcher found early evidence of atherosclerosis in children with a congenital disorder of homocysteine metabolism called homocystinuria.

Experimental trials that implicate homocysteine

• The European Concerted Action Project studied 1550 subjects and found that higher levels of Homocysteine in the blood caused TWICE the risk of coronary atherosclerosis as compared to persons with normal levels. These patients also had low levels of Folic Acid and Vitamin B-6.
• Twenty five percent of patients studied by Nygaard et al who had high Homocysteine blood levels (above 15 micro-mol/L) had died of heart disease during a five year period. In contrast, only 4 % of the patients who had normal homocysteine levels died.

To be fair, though, not all evidence incriminates Homocysteine. The MRFIT trial found no effect of Homocysteine on heart disease risk after adjustments were made for other risk factors.

How do Vitamins affect Homocysteine levels ?

Homocysteine is degraded by enzymes that depend on Vitamins for their action. Vitamin B-6, Folic Acid and Vitamin B-12 have all been found essential in removing Hcy from the blood, and so are protective factors for heart disease. The cases with high homocysteine levels in blood were identified to suffer from a concomitant deficiency of Vitamin B-6 and Folic Acid.

Dr.Gilbert Omenn, one of the pioneers in Homocysteine research, says

"On balance, we believe that the reduction of Homocysteine levels of above 15 micro-mol/L to below 10, is similar to the impact expected from a reduction in total cholesterol levels from 275 to 189 mg/dl"

Considering this, and the relationship between folic acid, homocysteine and cardiovascular risk, there is strong evidence for the potential benefits of increasing folic acid intake on a population wide basis.

Read the next article on Folic Acid and Vitamin B6 in Heart Disease