News Keeps Getting Worse for Vitamins

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November 20, 2008, 12:45 pm

http://well.blogs.nytimes.com/2008/11/20/news-keeps-getting-worse-for-

vitamins/

News Keeps Getting Worse for Vitamins

By Tara -Pope

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 cells, too.

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 s 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 disease.

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.