醫療資訊,議題討論 - 醫療資訊

Vitamin E linked to lung cancer
Vitamin E
High vitamin E doses were found to increase risk
Taking high doses of vitamin E supplements can increase the risk
of lung cancer, research suggests.

The US study of 77,000 people found taking 400 milligrams per day
long-term increased cancer risk by 28% - with smokers at
particular risk.

It follows warnings about similar risks of excessive beta-carotene
use.

Writing in the American Journal of Respiratory and Critical Care
Medicine, an expert said people should get their vitamins from
fruit and veg.


The jury's still very much out on whether vitamin and mineral
supplements can affect cancer risk
Henry Scowcroft, Cancer Research UK

Dr Tim Byers, from the University of Colorado, said a healthy,
balanced diet meant people took in a whole range of beneficial
nutrients and minerals, which might help to reduce cancer risk.

The researchers followed people aged between 50 and 76 for four
years and looked at their average daily use of vitamin C and folic
acid, and vitamin E supplements.

Over the course of the study, 521 people developed lung cancer.

Smoking, family history and age all had unsurprisingly strong
links to cancer risk.

And while neither vitamin C or folic acid use had any effect on
lung cancer risk, vitamin E use did.

The researchers extrapolated their findings, and concluded that
over a decade, there was an additional 7% increase in risk for
every 100 milligrams taken per day.

The vitamin E trend was most prominent among smokers, but was not
confined to them.

Vitamin E is known to be an antioxidant - protecting cells from
molecules called free radicals.

But the US researchers speculate that, in high doses, it may also
act as a pro-oxidant - causing oxidation and therefore damage to
cells.

'Toxic effects'

Dr Christopher Slatore of the University of Washington in Seattle,
who led the study, said: "In contrast to the often assumed
benefits or at least lack of harm, supplemental vitamin E was
associated with a small increased risk of lung cancer.

"Future studies may focus on other components of fruits and
vegetables that may explain the decreased risk of cancer that has
been associated with fruit and vegetables.

"Meanwhile, our results should prompt clinicians to counsel
patients that these supplements are unlikely to reduce the risk of
lung cancer and may be detrimental."

But Henry Scowcroft, senior science information officer at Cancer
Research UK, said: "The jury's still very much out on whether
vitamin and mineral supplements can affect cancer risk.

"Some studies suggest a benefit, but many others show no effect
and some, like this one, suggest they may even increase risk."

He added: "Research repeatedly shows that a healthy, balanced diet
can reduce your risk of some cancers while giving you all the
vitamins you need.

"Quitting smoking remains the most effective way to avoid many
cancers. There's no diet, or vitamin supplement, that could ever
counter the toxic effects of cigarette smoke."

In 2002 a Finnish study of 29,000 male smokers found taking
beta-carotene - which is converted into vitamin A in the body -
was linked to an 18% increased risk of developing lung cancer


http://news.bbc.co.uk/2/hi/health/7271189.stm


--