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What is Homocysteine and Definition
Homocysteine is an amino acid in the blood that the body’s metabolism of the essential amino acid methionine produces. (An essential amino acid is one the body cannot synthesize itself but must obtain from dietary sources.) B vitamins and folic acid are necessary to break down homocysteine. Accumulation of homocysteine in the blood circulation appears to accelerate development of ATHEROSCLEROSIS. In the mid-1990s researchers discovered a connection between elevated blood homocysteine levels and early atherosclerosis.
Doctors had known since the 1960s of a rare genetic condition, homocystinuria, that caused extensive atherosclerotic disease in teens and young adults. But new research led them to correlate atherosclerosis with elevated homocysteine levels in adults who had no known genetic foundation for them.
Some researchers believe that elevated homocysteine irritates the inside walls of the arteries. The irritation causes INFLAMMATION, which opens the way for ATHEROSCLEROTIC PLAQUE to infiltrate the intima, the innermost layer of the arterial walls. People between the ages of 45 and 60 who have significant atherosclerosis or CORONARY ARTERY DISEASE (CAD) often have elevated homocysteine levels. In people who have elevated homocysteine levels, atherosclerosis may develop more rapidly and at earlier ages. However, research studies as yet have not established a cause and effect relationship between elevated homocysteine and early atherosclerosis.
Homocysteine Blood Test and Heart Disease
A blood test can measure the homocysteine level in the blood. Most doctors view homocysteine as a risk factor for CARDIOVASCULAR DISEASE (CVD), though not one that is alone significant enough to cause cardiovascular disease. They recommend people receive the minimum daily amounts of vitamins B6, B12, and folic acid through dietary sources when possible and with supplements if necessary, as a matter of general health as well as to aid in breaking down homocysteine.
People who have elevated homocysteine levels along with other RISK FACTORS FOR CARDIOVASCULAR DISEASEshould do what they can to reduce their overall risks, though health experts do not advise folic acid supplementation beyond the recommended intake (400 micrograms daily for an adult) as a preventive measure for cardiovascular health. Adequate folic acid intake appears essential for numerous health reasons, and may help reduce the risks for other health conditions.
See also COENZYME Q10; DIET AND CARDIOVASCULAR HEALTH; NEURAL TUBE DEFECTS.