Homocysteine, an amino acid normally found in the body has a metabolism that is linked to that of several vitamins, especially folic acid, B6, and B12, and deficiencies of those vitamins may cause elevated levels of homocysteine. Studies suggest that those with elevated homocysteine levels have a much greater risk of heart attack or stroke than those with average levels. Increased concentrations of homocysteine have been associated with increased tendency to form in appropriate blood clots. This can lead to heart attack, strokes, and blood vessel blockages in any part of the body.