[Homocysteine. The cardiovascular risk factor of the next millennium?].

Several epidemiologic studies have demonstrated that hyperhomocysteinemia is a risk factor for arteriosclerosis in coronary, cerebral, peripheral and aortic arteries. This risk is independent of other cardiovascular risk factors, and it is dose related. However, prospective studies show contradictory findings. Hyperhomocysteinemia is also associated with a higher risk of venous thrombosis to which other coagulation disorders, such as factor V Leiden, could contribute. Hyperhomocysteinemia can be due to genetic defects in the enzymes that control homocysteine metabolism, and also to other factors, mainly nutritional (deficiencies in vitamin B6, vitamin B12, or folic acid). Dietary supplements of these vitamins reduce plasma homocysteine levels. Randomized clinical trials are still needed to demonstrate that reducing plasma homocysteine levels will reduce the risk for cardiovascular disease.