Homocysteine is an amino acid normally found in small amounts in the blood. High homocysteine levels in the blood can also cause cholesterol to change to something called oxidized low-density lipoprotein (LDL), which is more damaging to the arteries. In addition, high homocysteine levels can make blood clot more easily than it should, increasing the risk of blood vessel blockages. These, in turn, may increase a person’s risk of stroke, heart attack (myocardial infarction), and pulmonary embolism. Also, increased homocysteine levels may promote the formation of blood clots in the deep veins of the legs (called deep venous thrombosis, or DVT).
Blood levels of homocysteine may increase if a person’s diet is deficient in certain B vitamins (folic acid, vitamin B6, and vitamin B12). High levels of homocysteine in the blood can be lowered with adequate dietary intake of these B vitamins.
In addition to dietary deficiency of B vitamins, there are other factors that may increase a person’s blood homocysteine level, including:
- A family history of elevated blood homocysteine.
- Age. Blood homocysteine levels rise with age in both men and women.
- Gender. Blood homocysteine levels are higher in men than in women. The reason for this is not totally understood but may be related to differences in muscle mass, hormones, or kidney function.
- Kidney disease. The level of homocysteine in the blood increases in kidney disease because the kidneys do not properly filter homocysteine from the blood.
- Medication use. Certain medications increase blood homocysteine levels. These medications include anticonvulsants (such as phenytoin), methotrexate, cyclosporine, levodopa, theophylline, niacin, and cholestyramine.
- Homocystinuria.
- The more a steak is cooked, the more homocysteine you’ll produce in digesting it, so don’t choose ‘well-done’ if you are having a problem in this area.
Homocysteine testing may be most valuable in evaluating the overall risk of heart disease for people who have a strong personal or family history of heart disease but who do not have other risk factors that can be controlled (such as smoking or high blood pressure).
S-Aadenosylhomocysteine, which is the precursor of homocysteme, appears to be a more sensitive marker for differentiating cardiovascular patients from control subjects than homocysteine.