LONDON - Vitamin E and beta-carotene pills are
useless for warding off major heart problems, and beta-carotene, a source of
vitamin A, may be harmful, an analysis of key studies has concluded.
Many experts say the finding, published this week in The Lancet medical
journal, settles the issue of antioxidant vitamins for heart health.
But others argue that the pills might still prove useful if started earlier
and that while they do not seem to prevent heart attacks and premature death,
further studies may show they help to delay the onset or progression of heart
disease or other blood vessel problems.
Antioxidant nutrients, especially vitamin E, were widely recommended a few
years ago as a way of keeping the heart healthy. However, several recent large
studies failed to show any benefit, and a few raised the possibility that the
pills might be harmful for some.
The latest research, conducted by scientists at the Cleveland Clinic
Foundation, analyzed the pooled results from 15 key studies involving nearly
220,000 people.
"The public health viewpoint would have to be that there's really nothing to
support widespread use of these vitamins," said Dr. Ian Graham, a professor of
cardiology at Trinity College in Dublin, Ireland.
Most of the participants in the studies either already had heart or blood
vessel disease or were at increased risk of such problems. Seven of the studies
involved vitamin E alone or in combination with other antioxidants. Eight
involved beta carotene alone or with other antioxidants. The follow-up period
ranged from one to 12 years.
The researchers found that vitamin E did not reduce death from cardiovascular
or any other cause and did not lower the incidence of strokes.
Beta carotene was linked with a 0.3 percent increase in the risk
cardiovascular death and a 0.4 percent increase in the risk of death from any
cause by the end of the study.
"For heart health, we've answered the question and one is potentially
hazardous," said one of the investigators, Dr. Mark Penn, a Cleveland Clinic
cardiologist.
Alice Lichenstein, nutrition spokeswoman for the American Heart Association, agreed.
"I think there are enough studies that have looked at a diverse enough group
of individuals that it's unlikely that we're going to have a flip-flop," said
Lichenstein, a professor of nutrition science and policy at Tufts University who
was not connected with the research.
The idea that antioxidant vitamins might ward off heart trouble was
plausible. Test tube studies indicated that antioxidants protect the heart's
arteries by blocking the damaging effects of oxygen. The approach works in
animals, and studies show that healthy people who eat vitamin-rich food seem to
have less heart disease.
However, experts say that perhaps antioxidants work when they are in food,
but not when in pills. Some even think antioxidants may have been a red herring
and that maybe people who eat vitamin-rich food generally take better care of
themselves and that's why they have lower heart disease risks.
However, Jeffrey Blumberg, a professor of nutrition and chief of the Tufts
antioxidants research lab, maintained that scientists should not write off
antioxidants for heart health just yet.
"If in a six-year study, the same number in the vitamin E group and the
control group died, but the ones in the vitamin E group died a little later in
that six-year period, that is something that needs to be looked at," Blumberg
said.
"Some of the studies showed benefits in other areas, such as ... cardiac
arrythmias, which suggested there were some benefits in some subsets of groups,"
he said.
John Hathcock, vice president of scientific and international affairs at the
Council for Responsible Nutrition, a trade group for makers of antioxidants and
other dietary supplements, noted that although animal studies and observations
in humans suggested the pills would best be used in healthy people, the key
studies were done in people who were already either sick or at elevated risk of
heart disease.
"Ultimately, the end points of deaths and heart attacks are valid, but if you
start when the person is already at high risk or has disease, then it may be too
late for the benefit to occur," Hathcock said.
