Molecular and Biochemical Aspects of Homocysteine in Cardiovascular Diseases

Homocysteine also known as the H-factor, is a naturally occurring amino acid and is a by-product of methionine metabolism in the body. It is a common amino acid (one of the building blocks that make up proteins) found in the blood and is acquired mostly from eating meat. 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.