Vitamin Trader - Healthy Discounts on Quality Vitamins

A flurry of reports linking high blood levels of the amino acid homocysteine with cardiovascular disease have left researchers pondering the strength of that relationship, its impact on women (since most of the studies were with men), and other possible risk factors.

In a study by the European Concerted Action Project, scientists gathered information on 750 men and women with atherosclerotic vascular disease from 19 medical centers in nine European countries. Patients' blood homocysteine levels were measured while they fasted and again after they received 100 mg of the amino acid methionine per kg body weight--homocysteine is a natural metabolic product of methionine and too much methionine stresses the body's metabolic pathways.

Researchers also took blood pressures, smoking histories and blood samples to measure cholesterol and vitamins such as B12, B6 and folate that are involved in homocysteine metabolism. All data were compared to data from a control group of 800 people.

People with the highest levels of homocysteine had more than double the risk of vascular disease than people with lower amounts in their blood. The risk was greater, but not significantly so, in women. Homocysteine not only acted as a strong, independent risk factor for heart disease, but also interacted with other factors, especially smoking and high blood pressure. Smokers who also had elevated fasting levels of homocysteine incurred increased risk by a factor of 4.6. Those smokers with both high blood pressure and high fasting homocysteine levels had more than 11 percent increased risk.

The authors noted, "Control of smoking and hypertension may be particularly important in subjects with elevated tHcy [total homocysteine] levels, and estimations of plasma tHcy should now be considered as part of total vascular disease risk assessment."

Blood levels of the three B vitamins (B6, B12 and folate) were inversely related to homocysteine levels. Previous studies have shown that folate supplementation lowers homocysteine levels and that B6 can lower homocysteine after a methionine load. In this study, the people who took vitamin B supplements had lower homocysteine levels and an apparent lower risk of vascular disease.

The authors concluded, "We believe it is time to consider whether existing RDAs of the vitamins that modulate homocysteine metabolism are adequate and to undertake randomized controlled trials of the effects of folic acid and perhaps pyridoxine (B6) in the secondary prevention of cardiovascular disease."
--JAMA, 277(22): 1775-81, 1997.