Hyperhomocysteinemia: An emerging risk factor for cardiovascular disease

Abstract

There is considerable epidemiological evidence, which confirms the importance of plasma homocysteine as a powerful predictor of future risk of coronary heart disease and other complications of atherosclerosis. Treatment of hyperhomocysteinemia varies with the underlying cause. However, an inexpensive vitamin supplementation with folic acid, vitamin B12 and vitamin B 6 is generally effective in reducing homocysteine concentrations. Several randomised, controlled trials evaluating the effects of folic acid based supplements on homocysteine concentrations have been conducted over the last decade. In most patients, folic acid alone, and in combination of vitamin B12 and B6, has been shown to reduce homocysteine concentrations within four to six weeks after the initiation of therapy (34).However, no study has yet demonstrated that lowering of homocysteine by vitamin supplementation decreases the cardiovascular morbidity or mortality. Avoidance of excessive meat intake and increased consumption of fresh vegetables and fruits is a dietary measure, which has many health benefits, including a potential to reduce elevated homocysteine levels. The other reasonable approach is to determine levels of fasting homocysteine in high risk patients and it may be advisable to increase their intake of vitamin fortified foods and/or to suggest the daily use of supplemental vitamins. Several large scale randomised trials like Heart Outcomes Prevention Evaluation (HOPE-2) Study, Mcmaster University, Canada, Study of the Effectiveness of Additional Reductions in Cholesterol and Homocysteine (SERCH), Clinical Trial Service Unit, Oxford, U.K, Cambridge Heart Antioxidant Study (CHAOS-2) University of Cambridge, U.K, Bergen Vitamin Study, University of Bergen Norway, Women's Antioxidant and Cardiovascular Disease Study (WACS) Harvard Medical School, U.S.A, Prevention with a combined inhibitor and folate in Coronary Heart Disease (PACIFIC) study, University of Sydney, Australia, and many others are ongoing to assess the effect of homocysteine-lowering by vitamin supplementation on risk of vascular disease.