[ExI] NY Times: News Keeps Getting Worse for Vitamins
mlatorra at gmail.com
Fri Nov 21 05:19:02 UTC 2008
News Keeps Getting Worse for Vitamins:
The best efforts of the scientific community to prove the health benefits of
vitamins keep falling short.
Consumers don't want to give up their vitamins. (Tony Cenicola/The New York
Times)This week, researchers reported the disappointing results from a large
clinical trial of almost 15,000 male doctors taking vitamins E and C for a
decade. The study showed no meaningful effect on cancer rates.
Another recent study found no benefit of vitamins E and C for heart disease.
In October, a major trial studying whether vitamin E and selenium could
lower a man's risk for prostate cancer ended amidst worries that the
treatments may do more harm than good.
And recently, doctors at Memorial Sloan-Kettering Cancer Center in New York
warned that vitamin C seems to protect not just healthy cells but cancer
Everyone needs vitamins, which are critical for the body. But for most
people, the micronutrients we get from foods usually are adequate to prevent
vitamin deficiency, which is rare in the United States. That said, some
extra vitamins have proven benefits, such as vitamin B12 supplements for the
elderly and folic acid for women of child-bearing age. And calcium and
vitamin D in women over 65 appear to protect bone health.
But many people gobble down megadoses of vitamins believing that they boost
the body's ability to mop up damaging free radicals that lead to cancer and
heart disease. In addition to the more recent research, several reports in
recent years have challenged the notion that vitamins are good for you.
A Johns Hopkins School of Medicine review of 19 vitamin E clinical trials of
more than 135,000 people showed high doses of vitamin E (greater than 400
IUs) increased a person's risk for dying during the study period by 4
percent. Taking vitamin E with other vitamins and minerals resulted in a 6
percent higher risk of dying. A later study of daily vitamin E showed
vitamin E takers had a 13 percent higher risk for heart failure.
The Journal of Clinical Oncology published a study of 540 patients with head
and neck cancer who were being treated with radiation therapy. Vitamin E
reduced side effects, but cancer recurrence rates among the vitamin users
were higher, although the increase didn't reach statistical significance.
A 1994 Finland study of smokers taking 20 milligrams a day of beta carotene
showed an 18 percent 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, but the study was stopped
when the participants taking the combined therapy showed a 28 percent higher
risk for lung cancer and a 26 percent higher risk of dying from heart
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 percent higher risk for hip fractures than nurses who had the
lowest intake of vitamin A.
The Cochrane Database of Systematic Reviews looked at vitamin C studies for
treating colds. Among more than two dozen studies, there was no overall
benefit for preventing colds, although the vitamin was linked with a 50
percent reduction in colds among people who engaged in extreme activities,
such as marathon runners, skiers and soldiers, who were exposed to
significant cold or physical stress. The data also suggested vitamin C use
was linked with less severe and slightly shorter colds.
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 percent higher death rate than placebo users.
Two studies presented to the American College of Cardiology in 2006 showed
that vitamin B doesn't prevent heart attacks, leading The New England
Journal of Medicine to say that the consistency of the results "leads to the
unequivocal conclusion" that the vitamins don't help patients with
established vascular disease.
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.
Despite a lack of evidence that vitamins actually work, consumers appear
largely unwilling to give them up. Many readers of the Well blog say the
problem is not the vitamin but poorly designed studies that use the wrong
type of vitamin, setting the vitamin up to fail. Industry groups such as the
Council for Responsible Nutrition also say the research isn't well designed
to detect benefits in healthy vitamin users.
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