The evidence, however, is not consistent. One study conducted at the Harvard Medical School did not find that elevated homocysteine levels increased the risk of arterial narrowing. And other good studies have failed to identify high homocysteine levels as an independent risk factor for heart disease. Some people wonder if high levels might be the result, rather than the cause, of heart disease. It's apparent that low blood levels of folate and vitamin B-12 (and to a lesser extent B-6) are associated with high homocysteine levels and that increasing your intake of these vitamins can lower homocysteine. What's still unknown is whether consuming B vitamins also reduces your risk of heart disease. Evidence is mounting, and studies are now underway, but it will take time to come up with the answer.

You may be wondering whether you should have your homocysteine level measured. In fact, unless you have a

family history of early heart attacks or have already had a heart attack and your doctor wants to check your level, you don't need to have it measured. The problem is that there's no clear definition of normal or desirable levels. Another problem: it remains to be proven that lowering high homocysteine levels will actually reduce the risk of heart attack and stroke (except in those with homocystinuria).

Thus homocysteine has not "replaced" cholesterol as a health concern. (Don't go back to cream and butter!) The homocysteine theory fills in some blanks in the puzzle. For example, many people with coronary artery disease don't have high blood cholesterol levels, but may have high homocysteine.

No need to wait for certainties

What you can do, without getting any test and without hesitation, is to increase your consumption of B vitamins. If you eat well, and particularly if you consume fortified foods, you can get all these vitamins from your diet. Folacin and B-6 present few problems: they are plentiful in leafy greens, whole grains, some fruits, and fortified breakfast cereals. Cereal grain and white flour (breads, pasta, grits, white rice, and cornmeal) are now fortified with folic acid—chiefly because folic acid is important in preventing certain birth defects. A good target is at least 400 micrograms daily, especially for women of child-bearing age. (No one knows if such levels of folic acid intake are enough to reduce the risk of heart disease, but they can't hurt.)

Vitamin B-12 does present some concerns: it is found chiefly in meat, organ meats, eggs, and other foods that tend to be high in cholesterol and saturated fat (definitely not good for the arteries). But fortified cereals, fish, lean meats, and milk do supply vitamin B-12. The chart at left will guide you.

If you don't eat at least five fruits and vegetables a day, as well as fortified cereals and small servings of lean meat, poultry, or fish, do consider taking a daily multivitamin supplement providing 100% of the RDA of these B vitamins.

The folic acid and B-12 in supplements and fortified foods are much better absorbed by the body than the folacin and B-12 found naturally in food. Thus, recent studies have shown that people who take folic acid supplements decrease their homocysteine levels more than those who get more folate from food.

Keep in mind: Only a comprehensive program can prevent heart disease: not smoking; eating a diet rich in fruits, whole grains, fortified foods, and vegetables, and low in animal fats; and regular exercise such as brisk walking. Regular checkups for blood pressure and blood cholesterol are important, too.