Homocysteine Facts and Recommendations about Total.pdf

Does Lowering Homocysteine
 Prevent Cardiovascular Disease?Stephen Barrett, M.D.

   In 1969, a connection between homocysteine (a sulfur-containing amino acid) and cardiovascular disease    was proposed when it was observed that people    with a rare hereditary condition called homocystinuria are prone to develop    severe cardiovascular disease in their teens and twenties. In    this condition, an enzyme deficiency causes homocysteine to accumulate  in the blood and to be excreted in the urine.  Abnormal homocysteine elevation also occurs among    people whose diet contains inadequate amounts of folic acid, vitamin    B6, or vitamin B12. Regardless of the cause of the elevation,    supplementation with one or more of these vitamins can lower plasma  homocysteine levels.

Studies done in the 1980s and 1990s linked  elevated blood levels of homocysteine    to increased    risk of premature coronary artery disease, stroke, and venous blood clots, even among people with normal cholesterol    levels [1-8]. These studies led to  speculations that high homocysteine levels could contribute to atherosclerosis    in at least three ways: (a) a direct toxic effect that damages    the cells lining the inside of the arteries, (b) interference    with clotting factors, and (c) oxidation of low-density lipoproteins    (LDL). Lowering the serum concentration of homocysteine has been proven    to reduce the risk of adverse cardiovascular events among people    with homocystinuria. Without clinical trials, however, it was impossible to know whether abnormal homocysteine levels among the general population cause atherosclerosis or are merely a "marker"—a non-causative finding that often occurs in people with atherosclerosis.

Unfortunately, large controlled studies have found that treatment with B-vitamins does not reduce the incidence of cardiovascular events despite significant lowering of homocysteine levels [10-14]. In fact, a 7-year study of women with kidney disease secondary to diabetes found that those who took the B-vitamin supplemnent more heart attacks and strokes than those who did not [15].

Enough study has been done to conclude with reasonable certainty that taking B-vitamins to lower homocysteine levels will not lower the incidence or heart attacks or strokes except for people with homocystinurea. Nor is it advisable to do routine screening for homocysteine levels [16].    

References

http://www.quackwatch.com/03HealthPromotion/homocysteine.html

 

 

 

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