Does Folic Acid Lower Levels Of Homocysteine?

Homocysteine is an amino acid formed from the metabolism of methionine, another amino acid that you must obtain from your diet. In 1969, Dr. Kilmer McCully at Harvard Medical School first linked elevated homocysteine levels to a higher risk for atherosclerosis, or hardening of the arteries. Although supplementation with folic acid lowers your homocysteine level, it is still not clear if such therapy reduces your overall risk for heart attacks and strokes.

Metabolism

Homocysteine is important for cell and tissue health, bone formation and insulin formation. It is synthesized in your body from methionine through an enzyme-mediated, multi-step process. Homocysteine then has two metabolic fates in your cells: It can be converted to cysteine, another useful amino acid, or it can be recycled to form methionine. Vitamin B6 is needed to synthesize cysteine from homocysteine. Vitamin B12 and folic acid are needed to convert homocysteine back to methionine.

Elevation

A December 2010 review in "Cleveland Clinic Journal of Medicine" cites three main causes for elevated homocysteine levels in humans. Since your kidneys remove up to 70 percent of this amino acid from your bloodstream, kidney disease can increase your homocysteine level. Similarly, defects in the enzymes that metabolize homocysteine cause a "backup" of the amino acid in your circulation. Deficiencies of any of the vitamins that participate in homocysteine's metabolism contribute to high homocysteine levels. According to the Mayo Clinic, a normal homocysteine level is between 4.4 and 10.8 micromoles per liter.

Cardiovascular Effects

An elevated homocysteine level is associated with a higher risk of cardiovascular disease, but it isn't clear if homocysteine causes atherosclerosis or if it is simply a marker for another, more important process. Homocysteine certainly exerts undesirable cardiovascular effects -- decreased HDL synthesis, inhibition of arterial relaxation, promotion of arterial inflammation and stimulation of arterial thickening -- but lowering homocysteine levels has not been consistently shown to prevent heart attacks and strokes.

Considerations

Folic acid supplementation lowers homocysteine levels, but it has not been definitively shown to reduce your risk for cardiovascular events, such as heart attacks and strokes. However, if your homocysteine level is elevated on the basis of vitamin deficiencies, other metabolic processes that are dependent on these nutrients could also be negatively impacted. Folic acid doses of 800 mcg daily were used in most clinical studies evaluating its effects on homocysteine levels. Because folic acid interacts with vitamin B12 in red blood cell production, you should see your doctor to have your B12 level checked before beginning folic acid supplementation.