Recent studies
show that many vitamins not only don't help. They may actually cause harm.
Every day, millions of Americans gobble down fistfuls of vitamins in a bid
to ward off ill health. They swallow megadoses of vitamin C in hopes of boosting
their immune systems, B vitamins to protect their hearts, and vitamin E, beta
carotene and other antioxidants to fight cancer.
It's estimated
that 70% of American households buy vitamins. Annual spending on vitamins
reached $7 billion last year...
But a troubling
body of research is beginning to suggest that vitamin supplements may be
doing more harm than good. Over the past several years, studies that were
expected to prove dramatic benefits from vitamin use have instead shown the
opposite.
Beta carotene was seen as a cancer fighter, but it appeared to promote lung
cancer in a study of former smokers. Too much vitamin A, sometimes taken to
boost the immune system, can increase a woman's risk for hip fracture. A study
of whether vitamin E improved heart health showed higher rates of congestive
heart failure among vitamin users.
And there are
growing concerns that antioxidants, long viewed as cancer fighters, may actually
promote some cancer and interfere with treatments.
Last summer,
the prestigious Medical Letter, a nonprofit group that studies the
evidence and develops consensus statements to advise doctors about important
medical issues, issued a critical report on a number of different vitamins,
stressing the apparent risks that have emerged from recent studies. The Food
and Nutrition Board of the National Academy of Sciences -- the top U.S. authority
for nutritional recommendations -- has concluded that taking antioxidant
supplements serves no purpose.
If vitamins may be doing more harm than good, what about other dietary supplements?
The Journal's Tara Parker-Pope examines some recent studies that suggest supplements
don't really work, and explains why the reality may be more complicated than
that.
"People
hear that if they take vitamins they'll feel better," says Edgar R. Miller,
clinical investigator for the National Institute on Aging and author of an
analysis that showed a higher risk of death among vitamin E users in several
studies. "But when you put [vitamins] to the test in clinical trials,
the results are hugely disappointing and in some cases show harm. People think
they are going to live longer, but the evidence doesn't support that. Sometimes
it's actually the opposite."
Not everybody
is buying these results. Consumers remain devoted to their vitamin regimens.
Industry groups such as the Council for Responsible Nutrition reject the recent
evidence, saying the research is flawed or the people studied were too sick
to start with, making it impossible to draw any broad conclusions for the
rest of us. "I don't think it's black and white," says Andrew Shao,
vice president of regulatory and scientific affairs for the council. "It's
important to know that a lot of these studies have been done in diseased populations.
I suppose the expectations are too high. These vitamins are not drugs. They
can't be expected to cure or reverse 20, 30 or 40 years of disease."
Everyone needs
vitamins, which are key nutrients the body can't make. But micronutrients
from foods usually are adequate to prevent vitamin deficiency, which is rare
in the U.S. Even so, vitamin B-12 supplements for the elderly and folic
acid for women of child-bearing age are recommended.
But the proven
benefits of a few supplements pale next to the growing concerns about widespread
vitamin use. Nobody knows why high doses of vitamins taken as pills might
cause harm. One theory has to do with free radicals, a common byproduct of
the normal chemical reactions that occur in cells. Every day cells get damaged
due to a variety of factors including sunlight, the foods we eat and natural
aging. This creates free radicals, highly reactive molecules that can damage
tissues and lead to cancer and heart disease. Although the body has several
ways of coping with free radicals, many people believe high doses of vitamins
help, mopping up free radicals before they can do much damage.
But the problem is that free radicals may serve an important purpose, sending
a powerful signal to the body's immune system, which enlists its own army
of soldiers to fight the free radicals and fix the damage. The theory is that
by taking vitamins, we undermine that message system and upset the balance
of antioxidants and free radicals in the body. It may be that vitamins clean
up the free-radical mess, but the immune system isn't alerted to fix the damage,
allowing disease to set in.
Another concern
is that while vitamins from food sources are necessary and good for you, consumers
today often scarf down vitamins at levels that are more like a pharmaceutical
dose than something found in nature. In a test tube, high doses of a single
antioxidant can turn bad, evolving into pro-oxidants -- meaning they start
to oxidize and create free radicals, causing the very problem you were trying
to prevent.
Here's a look
at what science shows about the risks and benefits of some particular vitamins.
VITAMIN E
Vitamin E has long been touted as beneficial to heart health, based in
part on observational studies that have shown diets rich in fruits and vegetables
containing E and other vitamins are associated with a decreased risk of coronary
disease. Vitamin E also has been studied as a way to help Alzheimer's disease
and to prevent prostate cancer.
But research
into vitamin E supplements has been disappointing. Most clinical trials in
recent years have been inconclusive or shown no benefit -- and some have suggested
harm. The University of California-Berkeley Wellness Letter, from the same
institution that discovered the vitamin in 1922, last year said it no longer
recommended vitamin E supplements because of the data showing no benefits.
Last year, Johns
Hopkins University researchers in Baltimore published a shocking finding.
After reviewing the data from 19 vitamin E clinical trials of more than 135,000
people, the analysis showed high doses of vitamin E (greater than 400 IUs)
increased a person's risk for dying during the study period by 4%.
Taking the vitamin E with other vitamins and minerals resulted in a 6%
higher risk of dying.
Not everyone
agrees with the methods used in the study. And most of the patients were already
unhealthy, so the results may not apply to healthy people.
Since the analysis
was published, another study of about 9,500 patients evaluated long-term use
of 400 IUs of vitamin E daily. The study didn't show any statistically meaningful
differences between vitamin users in terms of cancer, heart attacks or stroke,
but the vitamin E takers had a 13% higher risk for heart failure.
The risk of
taking vitamin E for cancer is also of concern. Last year, the Journal of
Clinical Oncology published a study of 540 patients with head and neck cancer
who were being treated with radiation therapy. The patients took 400 IUs of
vitamin E or a placebo. The supplement reduced side effects by nearly 30%.
But recurrence rates among the vitamin E users were 37% higher. The
finding was not statistically meaningful, but has raised concerns that vitamin
intake could hinder the effectiveness of treatments.
Not all the
vitamin E news has been bad. Last year, the Women's Health Study evaluated
use of 600 IUs of vitamin E every other day by nearly 40,000 healthy women.
Overall, there was no benefit of using vitamin E for major cardiovascular
events or cancer. But a subgroup analysis found there was a 24% lower risk
for cardiovascular deaths and a 26% reduction in major cardiovascular events
among women over 65. The researchers said those findings weren't conclusive,
however, in part because they contradict other clinical-trial evidence.
Another study,
called Select, is looking at whether vitamin E and selenium lower risk for
prostate cancer. The study won't finish for several years, but this summer
a safety monitoring committee will review the results to date to see whether
any significant risks or benefits have emerged. In February, another study
reported in the Journal of the National Cancer Institute showed no clear benefit
of vitamin E on prostate-cancer risk, although there was benefit among a subgroup
of smokers.
The Select trial
already offers a cautionary tale on vitamin use, says Eric Klein, head of
urologic oncology at the Cleveland Clinic and a Select investigator. Select
was started after a study of smokers in Finland looked at beta carotene and
vitamin E to prevent lung cancer. While vitamin E users had an unexpected
lower risk for prostate cancer, the beta carotene users had a higher risk
for lung cancer. "The psyche of the U.S. population is that a nutraceutical
can't be harmful and might be helpful, so why not take it?" says Dr.
Klein. "That thinking is just not correct. The message is: Be careful
until the data is in."
BETA CAROTENE
AND VITAMIN A
Vitamin A is a family of compounds that play a role in vision, bone health,
cell division and the regulation of the immune system. Retinol is one of the
most usable forms of vitamin A. Several carotenoids, the darkly colored pigments
found in many plant foods, can be converted to vitamin A, but beta carotene
is the carotenoid that is most efficiently converted to vitamin A.
Although studies
have suggested an association between diets rich in beta carotene and vitamin
A and a lower risk for many types of cancer, the supplements taken in pill
form have proved risky.
The 1994 Finland
study of smokers taking 20 milligrams a day of beta carotene showed an 18%
higher incidence of lung cancer among beta carotene users. In 1996, a study
called Caret looked at beta carotene and vitamin A use among smokers and workers
exposed to asbestos. The trial was stopped when the participants taking the
combined therapy showed a 28% higher risk for lung cancer and a 26%
higher risk of dying from heart disease.
More recently,
a 2002 Harvard study of more than 72,000 nurses showed that those who consumed
high levels of vitamin A from foods, multivitamins and supplements had a 48%
higher risk for hip fracture than nurses who had the lowest intake of vitamin
A. Notably, nurses who ate a lot of foods high in vitamin A also had higher
risk, possibly indicating that too many foods are now fortified with the vitamin.
Milk, margarine and breakfast cereals are fortified with vitamin A. High intake
of vitamin A has also been associated with a higher risk of birth defects.
VITAMIN C
Ever since Nobel laureate Linus Pauling extolled the virtues of vitamin
C more than 30 years ago, Americans have been taking handfuls of the pills,
convinced the vitamins do everything from preventing colds to fighting cancer.
But like other vitamin studies, research into vitamin C has been disappointing.
Last summer,
the Cochrane Database of Systematic Reviews looked at the clinical-trial evidence
for vitamin C supplements in treating the common cold. Among 23 studies, there
was no overall benefit to using vitamin C to prevent colds. However, six studies
of marathon runners, skiers and soldiers exposed to significant cold or physical
stress showed about a 50% reduction in colds with vitamin C use. But
the investigators warned that these were extreme circumstances and probably
don't apply to the general population. Vitamin C may slightly shorten the
duration of colds, but the investigators said the small difference may not
even be noticed by patients.
There are also
concerns about risks associated with vitamin C. A 1999 analysis in the British
Medical Journal showed that in three studies, vitamin C didn't lower death
rates among elderly people, and may actually have increased the risk of dying
slightly. Last year, the cancer journal CA reported that antioxidant supplements,
including vitamin C, should be avoided by patients being treated for cancer.
Scientists have found that cancer cells gobble up vitamin C faster than normal
cells, suggesting that any protection vitamin C gives might be even greater
for tumors than normal cells. In 2001 scientists showed that cancer cells
may become resistant to chemotherapy drugs after treatment with vitamin C.
"It's a mistake to think that cancer cells...don't like nutrients,"
says Gabriella D'Andrea, oncologist with Memorial Sloan-Kettering Cancer Center
in New York and author of the review.
Whether any
of the antioxidant vitamins are cancer fighters or cancer promoters remains
an open question. Although some data suggest a benefit, others suggest harm.
In October 2004 Copenhagen researchers reviewed seven randomized trials of
beta carotene, selenium, and vitamins A, C and E (alone or in combination)
in esophageal, gastric, colorectal, pancreatic and liver cancer. The antioxidant
users had a 6% higher death rate than placebo users.
B VITAMINS
A regimen of B vitamins, including folic acid, vitamin B-12 and vitamin
B-6, has been touted as a way to improve heart health by lowering homocysteine,
an amino acid thought to be a risk factor for heart attack. But last week,
two studies presented to the American College of Cardiology showed that while
the vitamins do lower homocysteine levels, taking them doesn't lower risk
for heart attack.
The patients
in the studies weren't healthy. They had diabetes, heart disease or a history
of heart attack. The New England Journal of Medicine said the consistency
of the results "leads to the unequivocal conclusion" that the vitamins
don't help patients with established vascular disease.
But the medical
community remains divided on whether the vitamins might still be useful for
healthy people. "This should not close the book on the investigation
of whether B vitamins in a healthy population helps reduce risk of cardiovascular
disease," says Dr. Shao of the Council for Responsible Nutrition.
Not all the
research into vitamin B is controversial. Folic acid supplements for women
of child-bearing age have dramatically reduced the incidence of neural-tube
defects in babies. Elderly people can develop an inability to absorb vitamin
B-12 from food, so supplements may be recommended as we get older.
CALCIUM AND
VITAMIN D
A 2005 study in the British Medical Journal didn't show any reduction
in fracture risk among women who took 1,000 milligrams of calcium with 800
IUs of vitamin D a day. But the Women's Health Initiative recently suggested
that calcium and vitamin D may lower hip-fracture risk in women over 60. Calcium
users, however, had a 17% higher risk for kidney stones.
Elderly people,
particularly those who have dark skin, get little exposure to sunlight and
don't drink milk, are at risk for vitamin D deficiency and are typically advised
to take supplements. One study suggests the most benefit comes with about
800 IUs of vitamin D a day.
Most doctors
and health experts now suggest that consumers interested in taking vitamins
stick to a multivitamin rather than concoct their own cocktails of high-dose
vitamins. But even this practice is being questioned because there's little
evidence to support it. In August the British Medical Journal looked at
multivitamin use among elderly people for a year, but found no difference
in infection rates or visits to doctors.
Researchers
urge caution when interpreting results from various vitamin studies. Many
factors, ranging from the type of vitamin to the age and health of the participants,
may influence the results, says Marion Dietrich, postdoctoral associate in
the Nutritional Epidemiology Program at Tufts University. What is clear,
however, is the important role a healthful diet plays in preventing illness.
Large dietary-intervention studies have shown that a healthful diet
reduces risk of cardiovascular disease.
But doctors
say many patients view vitamins as a quick fix to compensate for poor eating
habits, and resist any suggestion that taking them may not be beneficial.
"A lot of people are passionate about their vitamins," says Dr.
Miller of the National Institute on Aging. "I don't know where they get
it from, but it's not based on scientific evidence."
What I Got
Wrong About the War
As conservatives pour out their regrets, I have a few of my own to confess
By ANDREW SULLIVAN
Was I wrong
to support the war in Iraq? Several conservatives and neoconservatives have
begun to renounce the decision to topple Saddam Hussein three years ago. William
F. Buckley Jr., as close to a conservative icon as America has, recently wrote
that "one can't doubt that the American objective in Iraq has failed."
George F. Will has been a moderate skeptic throughout. Neoconservative scholar
Francis Fukuyama has just produced a book renouncing his previous support.
The specter of Iraq teetering closer to civil war and disintegration has forced
a reckoning.
In retrospect,
neoconservatives (and I fully include myself) made three huge errors. The
first was to overestimate the competence of government, especially in
very tricky areas like WMD intelligence. The shock of 9/11 provoked an overestimation
of the risks we faced. And our fear forced errors into a deeply fallible system.
When doubts were raised, they were far too swiftly dismissed. The result was
the WMD intelligence debacle, something that did far more damage to the war's
legitimacy and fate than many have yet absorbed.
Fukuyama's sharpest
insight here is how the miraculously peaceful end of the cold war lulled many
of us into overconfidence about the inevitability of democratic change, and
its ease. We got cocky. We should have known better. The second error
was narcissism. America's power blinded many of us to the resentments that
hegemony always provokes. Those resentments are often as deep among our global
friends as among our enemies--and make alliances as hard as they are important.
That is not to say we should never act unilaterally. Sometimes the right thing
to do will spawn backlash, and we should do it anyway. But that makes it all
the more imperative that when we do go out on a limb, we get things right.
In those instances, we need to make our margin of error as small as humanly
possible. Too many in the Bush Administration, alas, did the opposite. They
sent far too few troops, were reckless in post-invasion planning and turned
a deaf ear to constructive criticism, even from within their own ranks. Their
abdication of the moral high ground, by allowing the abuse and torture of
military detainees, is repellent. Their incompetence and misjudgments might
be forgiven. Their arrogance and obstinacy remain inexcusable.
The final
error was not taking culture seriously enough. There is a large discrepancy
between neoconservatism's skepticism of government's ability to change culture
at home and its naiveté when it comes to complex, tribal, sectarian
cultures abroad.
We have learned
a tough lesson, and it has been a lot tougher for those tens of thousands
of dead, innocent Iraqis and several thousand killed and injured American
soldiers than for a few humiliated pundits. The correct response to that is
not more spin but a real sense of shame and sorrow that so many have died
because of errors made by their superiors, and by writers like me. All this
is true, and it needs to be faced. But it is also true that we are where we
are. And true that there was no easy alternative three years ago. You'd like
Saddam still in power, with our sanctions starving millions while U.N. funds
lined the pockets of crooks and criminals? At some point the wreckage that
is and was Iraq would have had to be dealt with. If we hadn't invaded, at
some point in the death spiral of Saddam's disintegrating Iraq, others would.
It is also true that it is far too soon to know the ultimate outcome of our
gamble.
What we do know
is that for all our mistakes, free elections have been held in a largely Arab
Muslim country. We know that the Kurds in the north enjoy freedoms and a nascent
civil society that is a huge improvement on the past. We know that the culture
of the marsh Arabs in the south is beginning to revive. We know that we have
given Iraqis a chance to decide their own destiny through politics rather
than murder and that civil war is still avoidable. We know that the enemies
of democracy in Iraq will not stop there if they succeed. And we know that
no perfect war has ever been fought, and no victory ever won, without the
risk of defeat. Despair, in other words, is too easy now. And it too is a
form of irresponsibility.
Regrets? Yes.
But the certainty of some today that we have failed is as dubious as the callow
triumphalism of yesterday. War is always, in the end, a matter of flexibility
and will. And sometimes the darkest days are inevitable--even necessary--before
the sky ultimately clears.
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