B vitamins diminish heart disease risk.

In 1968, Kilmer McCully, a researcher at Harvard University, Cambridge, Mass., proposed a link between elevated blood levels of homocysteine (a breakdown product of protein metabolism) and the development of coronary heart disease. Few took his theory seriously then, but today, the impact of his discovery finally is being appreciated. Elevated homocysteine, which can be caused by inadequate intakes of the B vitamin folic acid, is recognized as an important risk factor for heart disease.

According to McCully, now a staff pathologist at the Providence (R.I.) Veterans Administration Medical Center, numerous studies have confirmed his finding that elevated homocysteine is an independent risk factor for arteriosclerosis, heart attack, stroke, and vascular disease. In the Framingham (Mass.) Study, which has been monitoring causes of heart disease for more than 50 years, there was a strong correlation between blood levels of homocysteine and occurrence of stenosis (narrowing of the arteries due to plaque buildup). Stenosis appeared in 58% of men with the highest levels of homocysteine, compared with 27% in the lowest levels. Approximately two-thirds of all cases of elevated homocysteine were associated with inadequate intakes of one or more of [B.sub.6], [B.sub.12], and folate.

The sole source of homocysteine in the body is the amino acid methionine, which comes from dietary proteins. During normal metabolism, methionine continually is converted to homocysteine and back to methionine. Vitamins [B.sub.6], [B.sub.12], and folic acid are essential for these conversions to occur. Without proper metabolism, the buildup of...