Chemical names used in medicine often find their way into common use. Cholesterol is a good example. Since various forms of blood cholesterol are correlated with the risk of developing cardiovascular disease, blood cholesterol is routinely measured to help physicians make decisions about an individual’s health care needs.

There is another chemical that is becoming increasingly important because of its relationship to heart disease and a number of other diseases. Homocysteine — often abbreviated Hcy — is the upcoming blood test to help with determining risk.

QUESTION: Was Hcy recently discovered?

ANSWER: No. Biochemists have known about the molecule for about 100 years. Almost 50 years ago, a researcher named Kilmer McCully proposed that high blood levels of Hcy were a risk factor for cardiovascular disease. It took about 20 years for McCully’s initial proposal to be appreciated by other researchers. Now, Hcy is one of the most studied substances because it is being linked with a variety of disease conditions.

Q: What conditions are related to a high blood Hcy level?

A: A number of studies have confirmed a link between high Hcy and cardiovascular (heart and blood vessel) disease. At least 10 percent of the U.S. population has high blood Hcy due to their genetics, and they are very likely to have cardiovascular disease or to develop it in the future.

Mental decline with age and the development of dementia progresses more rapidly in those with high blood Hcy. There even is evidence that Hcy may contribute to the development of Alzheimer’s disease.

Many things contribute to hearing loss with age and research is finding that high Hcy plays a significant role. Some types of vision loss also may be affected by Hcy, but the evidence for that is currently limited.

Q: What causes Hcy to be elevated?

A: In addition to a variety of relatively common genetic defects, nutrition plays a significant role. Inadequate intake of vitamins B6, B9 (folate) and B12 can increase Hcy.

Q: How can Hcy be lowered?

A: For those with genetically induced high Hcy, studies show that supplementation with the three B vitamins — B6, B9 and B12 — can significantly reduce Hcy. Typical doses in these studies are about 20 mg/day of B6, 800 mcg/day of B9 and 500 mcg/day of B12.

Q: Can you take too much of the B vitamins?

A: Yes. Excess vitamin B6 is well known to cause damage to nerves. High B9 intake in someone with low vitamin B12 status was found to be harmful to cognitive health. This suggests that supplementing with B9 should be accompanied with B12 supplementation.

Q: What foods are good sources of B6, B9 and B12?

A: Good sources of vitamin B6 include fish, poultry, potatoes and chickpeas. B9 is high in most green vegetables and most beans, including edamame. Vitamin B12 is found in animal foods, including meat, fish, poultry, eggs and milk products. Many of the fortified breakfast cereals are rich in all three of these vitamins.

For those with a family history of cardiovascular disease, dementia or hearing loss, getting tested for blood Hcy level could be a good idea. If that is not possible, it could be wise to take a daily multivitamin supplement to reduce possible risks.

Alan Titchenal, Ph.D., C.N.S., and Joannie Dobbs, Ph.D., C.N.S., are nutritionists in the Department of Human Nutrition, Food and Animal Sciences, College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. Dobbs also works with University Health Services.