Are
B Vitamins Good For Your Heart?
One
of the most interesting new clues to heart disease is homo-cysteine.
It's a substance that we all produce from an amino acid (a building
block of protein) in food.
In
the normal course of events, the homocysteine that healthy people
manufacture is converted into amino acids that do them no harm.
This is accomplished by three B vitamins—B6, B12, and, probably
most important, folacin (also called folate or, when used in a
supplement or to fortify foods, folic acid). If the conversion
does not take place rapidly enough, due to a genetic defect or
vitamin deficiency, elevated levels of homocysteine may, the theory
goes, damage arterial walls and promote the buildup of cholesterol,
thus potentially leading to arterial blockage and a heart attack.
Many
studies, no certainties
An
impressive number of new homocysteine studies have appeared in
the past decade, and some have found that a high level of homocysteine
is an independent risk factor for heart disease, along with high
blood pressure and high blood cholesterol. In 1992, for example,
a large study found that men with homocysteine levels in the top
5% were at three times the risk for heart attack as those with
lower levels. A study in 1997 showed that high levels increased
the risk of death in those who already had heart disease. One
study of 1,500 men and women in 19 European medical centers found
that those who ranked in the top 20% for homocysteine levels had
double the risk of heart disease, compared to those with low homocysteine—similar
to the increased risk from smoking or high cholesterol. But people
in the study who took supplements of folic acid, B6, and B12 cut
their risk substantially. A study in Circulation
found a link between heart disease and high homocysteine levels
in young women—a group in which heart attacks are rare—particularly
when the women were deficient in folacin. This is just a sample
of the findings.
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 B12 (and to a lesser extent B6) 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.
Too
early to be tested
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 B6 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
B12 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
B12. 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 B12 in supplements and fortified foods are much
better absorbed by the body than the folacin and B12 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.
| Vitamin |
 |
Adult
RDA |
|
Sources |
| Folacin |
400
micro-
grams (mcg) |
Leafy
greens, broccoli, wheat germ, beans, whole grains, fortified
oatmeal.
1 cup cooked spinach has 260 mcg; 1 cup beans, 160 to 350
mcg.
|
| B6 |
1.3
milligrams (mg), women;
1.7 mg, men |
Whole
grains, bananas, potatoes, beans, fish, meat, poultry.
1 medium potato (baked, with skin) or banana has 0.7 mg.
|
| B12 |
2.4
mcg |
Meat,
poultry, liver, eggs, dairy, fish, fortified cereals and soy
products. 3 oz beef has 2 mcg;
1 cup milk, 0.9 mcg. |
Reference
Source 98,99,101
