Study Shows Need For B Vitamins In Diet

Current dietary advice often seems to be a moving target. All fat is bad; no, just some fats are bad. Carbohydrates are good; no, some carbohydrates are better than others and some are downright bad.

Yet, there have been some constants. No reputable scientist has yet had an unkind word to say about fruits, vegetables or whole grains. But just as research continues to reveal their benefits, several of their important nutrients - particularly the B vitamins - are not even listed on most food labels.

In a rush to embrace vitamin A and vitamin E to prevent heart disease, and vitamin C to prevent cancer, the B vitamins have been largely neglected.

But the importance of sufficient B vitamins in the diet has become more apparent every year, culminating in the publication this month of a study showing that adequate levels of at least two B vitamins, probably three, in the diet greatly reduces the risk of heart attack.

These findings were not news to Dr. Kilmer McCully, long a voice in the wilderness on the subject. Back in the 1970s, when he was a researcher at Harvard Medical School and Massachusetts General Hospital in Boston, McCully thought that homocysteine, an amino acid in the blood, could damage artery walls and cause heart disease. He also thought that homocysteine could be kept at safe levels by taking three B vitamins: B6, B12 and folate (folic acid). But his grants dried up because most scientists at the time were intent on pursuing cholesterol’s link to heart disease.

Homocysteine is found in large amounts in animal protein, which makes up a significant part of the American diet. Vitamin B6, B12 and folate are found in fruits, vegetables, beans and whole grains, which rank fairly low in the American diet.

By 1990, other studies were coming to the same conclusions McCully had reached. And this month, a study of 80,000 nurses that began in 1980 confirmed a direct link between adequate levels of vitamin B6 and folate and the reduced risk of heart attacks. Earlier, the well-known Framingham heart study had confirmed a direct link between heart health and vitamin B12. Other research has shown that adequate intake of folate by women of childbearing age could prevent neural tube defects in babies.

So what does this all mean to a health-conscious American trying to plan the day’s meals? Certainly, the easiest way to get enough of the B vitamins is to pop a supplement. Some now for sale provide what studies consider the optimal daily intake.

The nurses’ study showed 3 milligrams of vitamin B6 are needed daily, while the current government recommendation is 1.6 milligrams. For B12, the daily recommendation is 6 micrograms (millionths of a gram), though some studies urge more. For folate, the current recommended allowance is 180 micrograms, while the optimal level according to the study is 400 micrograms.

McCully, like many nutritionists, believes that food is the best source of vitamins because you also get fiber, which limits the absorption of cholesterol, plus beneficial antioxidants and thousands of other components whose values have yet to be discovered.

Today, unfortunately, it is harder than ever to find the B vitamins in packaged foods. After the new nutrition labeling went into effect a few years ago, it was no longer necessary to list the B vitamin content of foods, with the exception of those that are fortified, like cold cereals.

Good sources of folate include orange juice, black-eyed peas, asparagus, spinach, dried peas, beans and lentils, leafy greens, fish, broccoli, cantaloupe and chicken liver. Good sources of B6 are bananas, chicken, turkey, dried beans, whole grains, salmon, tuna, nuts and beef liver.

B12 is found almost exclusively in animal products - turkey, fish, red meat, eggs, milk - but it is only needed in small quantities, 5 to 15 micrograms a day. There is also a small amount in wheat germ.

Here’s a daily meal plan that provides 3 milligrams of B6, 9.3 micrograms of B12 and 699.2 micrograms of folate:

Breakfast: 1 cup raisin bran, 1/2 cup milk, 1 sliced banana, 1 cup orange juice.

Lunch: Salmon salad sandwich on whole-wheat bread with lettuce and tomato, 1/2 cup asparagus spears.

Snack: 1 cup fruit-flavored yogurt or 1 cup cantaloupe.

Dinner: 3 ounces sirloin steak (about the size of a deck of cards), 1 cup bulgur-lentil salad, 1/2 cup broccoli, 1 whole-wheat roll.