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Will Vitamin E Kill You, Or Save Your Life?
Research results send conflicting messages with
latest saying it increases risk of dying
Nov. 10, 2004 A research report will be presented
today that says daily doses of Vitamin E in excess of 400 IU
(international units) is associated with a higher overall risk of dying.
This is not the first study reporting on dangers of Vitamin E, but there
are many recent studies saying it helps senior citizens in the fight
against Alzheimers, heart disease and even vision problems.
Researchers at Johns Hopkins say their results
should be of concern to the millions of Americans who take vitamin E
supplements for perceived health benefits.
"Our study results do not support the use of
high-dose vitamin E supplements. If people are taking a multivitamin,
they should make sure it contains no more than a low dose of vitamin E,"
said study lead author and internist Edgar R. Miller III, M.D., Ph.D.,
associate professor of medicine at The Johns Hopkins University School
of Medicine. "A lot of people take vitamins because they believe it will
benefit their health in the long term and prolong life. But our study
shows that use of high-dose vitamin E supplements certainly did not
prolong life, but was associated with a higher risk of death."
The Hopkins team is scheduled to present their
findings at the American Heart Association's Scientific Sessions 2004 in
New Orleans, La., with simultaneous publication of their study in the
Annals of Internal Medicine online today.
The study results showed that people taking vitamin
E supplements of 400 IU or more per day had an increased risk of death.
Vitamin E capsules, used as supplements, typically
contain 400 IU to 800 IU. The study results indicated that these
high-dose supplements were associated with a higher risk of death.
In the current study, the Hopkins team re-analyzed
raw data from 19 major clinical trials, sorting information by whether
high- or low-dose levels of vitamin E were taken. Nine of these studies
tested vitamin E alone; 10 tested its use in combination with other
vitamins.
The 19 studies took place between 1993 and 2004 and
involved more than 136,000 patients in North America, Europe and China.
All of the studies involved use of a control group taking a dummy pill,
or placebo. Risk of death was estimated by comparing the death rates in
both groups. Follow-up periods ranged from 1.4 years to 8.2 years.
When the data for these trials was re-evaluated,
through a process called a meta-analysis, nine of 11 trials involving
high-dose vitamin E (400 IU per day, or more) showed an increased risk
of death. The other eight trials involved low-dose vitamin E users.
It was unclear whether low amounts (200 IU per day
or less) of vitamin E supplements increased a person's risk of death.
Because most of the patients in all of the trials
were over 60, and a majority had pre-existing conditions, such as heart
disease, the study's application to younger, healthy adults may be
limited, the Hopkins researchers point out.
Current United States dietary guidelines do not
recommend vitamin E supplementation; however, the guidelines do set an
upper tolerable intake limit of up to 1,500 IU per day.
"Policy makers and government regulators should
consider lowering this level, perhaps, to an upper limit of 400 IU per
day," said Eliseo Guallar, M.D., Dr.P.H., senior author of the study and
assistant professor of epidemiology at the Bloomberg School of Public
Health.
"Additional research is needed to determine the
effects, if any, of low-dose levels of vitamin E supplements. As well,
there are unresolved questions on the benefits of vitamin E when
combined with other antioxidants."
Vitamin E is one of 13 vitamins essential to body
metabolism, cell growth and function. It is also known as tocopherol and
is an antioxidant important in the formation of red blood cells and the
use of vitamin-K-mediated clotting factors. Sources of dietary intake
include wheat germ, corn, nuts, seeds, olives, spinach, asparagus and
other green leafy vegetables, vegetable oils, and products made from
vegetable oils, such as margarine. On average, dietary intake of vitamin
E is 10 IU per day. Multivitamin pills usually contain 30 IU to 60 IU of
vitamin E.
The research was
conducted at Johns Hopkins. Other researchers who participated in this
study were Roberto Pastor-Barriuso, Ph.D., Darshan Dalal, M.D., M.P.H.;
Rudolph Riemersma, Ph.D; and Lawrence Appel, M.D., M.P.H.
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