Snapshot of U.S. Homocysteine Levels

A profile of blood homocysteine levels across teenage and adult age groups in the U.S. confirms findings of earlier, nonrepresentative studies: This recently recognized risk factor for heart disease increases with age and is higher in males than females.

Homocysteine is produced during the conversion of one amino acid into another. Incomplete conversion causes a buildup of homocysteine in the blood where it is thought to irritate artery linings, encouraging formation of plaque--fatty deposits that cling to artery walls.

Paul Jacques and colleagues at the USDA Human Nutrition Research Center on Aging at Tufts, Boston, collaborated on the study with scientists at the Centers for Disease Control and Prevention in Atlanta, Ga., and Hyattsville, Md. The Boston center is funded by the Agricultural Research Service, USDA's chief scientific agency.

The researchers used sera from the latest National Health and Nutrition Examination Survey to measure homocysteine for 3,766 males and 4,819 females from age 12 up. Homocysteine levels between the two genders were closest in the young and old, diverging around puberty and converging after menopause.

Low intake of folate, vitamin B12 or vitamin B6 can be a cause for the homocysteine buildup. Orange juice and green leafy vegetables are good sources of folate, which seems the most limiting of the three vitamins.

One unexpected finding: Mexican-American females had the lowest homocysteine levels--significantly lower than non-Hispanic African-American and white subjects. The researchers don't have an explanation for this finding yet.

They suspect impaired kidney function may contribute to the higher homocysteine levels in older people. Body size, estrogen and vitamin status may explain the difference between genders.

A story about the research appears in the March issue of ARS' Agricultural Research magazine. The story is also on the World Wide Web at:

/is/AR/archive/mar99/snap0399.htm

Scientific contact: Paul Jacques, USDA Human Nutrition Research Center on Aging at Tufts, Boston, Mass., phone (617) 556-3322, fax (617) 556-3344, paul@hnrc.tufts.edu.