By PAUL A. OFFIT
The New York Times, June 8, 2013
PHILADELPHIA — LAST month, Katy Perry shared her secret to good health
with her 37 million followers on Twitter. “I’m all about that supplement &
vitamin LYFE!” the pop star wrote, posting a snapshot of herself holding up
three large bags of pills. There is one disturbing fact about vitamins,
however, that Katy didn’t mention.
Derived from “vita,” meaning life in Latin, vitamins are necessary to convert
food into energy. When people don’t get enough vitamins, they suffer diseases
like scurvy and rickets. The question isn’t whether people need vitamins. They
do. The questions are how much do they need, and do they get enough in foods?
Nutrition experts argue that people need only the recommended daily
allowance — the amount of vitamins found in a routine diet. Vitamin
manufacturers argue that a regular diet doesn’t contain enough vitamins, and
that more is better. Most people assume that, at the very least, excess
vitamins can’t do any harm. It turns out, however, that scientists have known
for years that large quantities of supplemental vitamins can be quite harmful
indeed.
In a study published in The New England Journal of Medicine in 1994,
29,000 Finnish men, all smokers, had been given daily vitamin E, beta carotene,
both or a placebo. The study found that those who had taken beta carotene for
five to eight years were more likely to die from lung cancer or heart disease.
Two years later the same journal published another study on vitamin
supplements. In it, 18,000 people who were at an increased risk of lung cancer
because of asbestos exposure or smoking received a combination of vitamin A and
beta carotene, or a placebo. Investigators stopped the study when they found
that the risk of death from lung cancer for those who took the vitamins was 46
percent higher.
Then, in 2004, a review of 14 randomized trials for the Cochrane
Database found that the supplemental vitamins A, C, E and beta carotene, and a
mineral, selenium, taken to prevent intestinal cancers, actually increased
mortality.
Another review, published in 2005 in the Annals of Internal Medicine,
found that in 19 trials of nearly 136,000 people, supplemental vitamin E
increased mortality. Also that year, a study of people with vascular disease or
diabetes found that vitamin E increased the risk of heart failure. And in 2011,
a study published in the Journal of the American Medical Association tied
vitamin E supplements to an increased risk of prostate cancer.
Finally, last year, a Cochrane review found that “beta carotene and
vitamin E seem to increase mortality, and so may higher doses of vitamin A.”
What explains this connection between supplemental vitamins and
increased rates of cancer and mortality? The key word is antioxidants.
Antioxidation vs. oxidation has been billed as a contest between good
and evil. It takes place in cellular organelles called mitochondria, where the
body converts food to energy — a process that requires oxygen (oxidation). One
consequence of oxidation is the generation of atomic scavengers called free
radicals (evil). Free radicals can damage DNA, cell membranes and the lining of
arteries; not surprisingly, they’ve been linked to aging, cancer and heart disease.
To neutralize free radicals, the body makes antioxidants (good).
Antioxidants can also be found in fruits and vegetables, specifically in
selenium, beta carotene and vitamins A, C and E. Some studies have shown that
people who eat more fruits and vegetables have a lower incidence of cancer and
heart disease and live longer. The logic is obvious. If fruits and vegetables
contain antioxidants, and people who eat fruits and vegetables are healthier,
then people who take supplemental antioxidants should also be healthier. It
hasn’t worked out that way.
The likely explanation is that free radicals aren’t as evil as
advertised. (In fact, people need them to kill bacteria and eliminate new
cancer cells.) And when people take large doses of antioxidants in the form of
supplemental vitamins, the balance between free radical production and
destruction might tip too much in one direction, causing an unnatural state
where the immune system is less able to kill harmful invaders. Researchers call
this the antioxidant paradox.
Because studies of large doses of supplemental antioxidants haven’t
clearly supported their use, respected organizations responsible for the
public’s health do not recommend them for otherwise healthy people.
So why don’t we know about this? Why haven’t Food and Drug
Administration officials made sure we are aware of the dangers? The answer is,
they can’t.
In December 1972, concerned that people were consuming larger and
larger quantities of vitamins, the F.D.A. announced a plan to regulate vitamin
supplements containing more than 150 percent of the recommended daily
allowance. Vitamin makers would now have to prove that these “megavitamins”
were safe before selling them. Not surprisingly, the vitamin industry saw this
as a threat, and set out to destroy the bill. In the end, it did far more than
that.
Industry executives recruited William Proxmire, a Democratic senator
from Wisconsin, to introduce a bill preventing the F.D.A. from regulating
megavitamins. On Aug. 14, 1974, the hearing began.
Speaking in support of F.D.A. regulation was Marsha Cohen, a lawyer
with the Consumers Union. Setting eight cantaloupes in front of her, she said,
“You would need to eat eight cantaloupes — a good source of vitamin C — to take
in barely 1,000 milligrams of vitamin C. But just these two little pills, easy
to swallow, contain the same amount.” She warned that if the legislation
passed, “one tablet would contain as much vitamin C as all of these
cantaloupes, or even twice, thrice or 20 times that amount. And there would be
no protective satiety level.” Ms. Cohen was pointing out the industry’s
Achilles’ heel: ingesting large quantities of vitamins is unnatural, the
opposite of what manufacturers were promoting.
A little more than a month later, Mr. Proxmire’s bill passed by a vote
of 81 to 10. In 1976, it became law. Decades later, Peter Barton Hutt, chief
counsel to the F.D.A., wrote that “it was the most humiliating defeat” in the
agency’s history.
As a result, consumers don’t know that taking megavitamins could
increase their risk of cancer and heart disease and shorten their lives; they
don’t know that they have been suffering too much of a good thing for too long.
Paul A. Offit is the chief of the
infectious diseases division of the Children’s Hospital of Philadelphia and the
author of the forthcoming book “Do You Believe in Magic?: The Sense and
Nonsense of Alternative Medicine.”
Source: http://www.nytimes.com/2013/06/09/opinion/sunday/dont-take-your-vitamins.html?pagewanted=all
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