ORLANDO, Florida (AP) -- Scientists in search of cancer-preventing
nutrients have found clues that vitamin E may protect against
bladder cancer.
Their study, released Sunday, found that people who get lots
of this vitamin in their food have only about half as much bladder
cancer as those who take in relatively little. While intriguing,
though, researchers say much more research is needed before
they can recommend more than eating plenty of vitamin-rich fruits
and vegetables.
Experts once had high hopes that vitamin E would prove to be
an important safeguard against heart attacks. But that idea
eventually faded as repeated studies failed to show any protective
effect.
Now, some think the vitamin may protect against cancer perhaps
by warding off the damaging effects of oxygen. The strongest
evidence of this so far has been against prostate cancer, and
a large federally sponsored experiment is under way to help
prove this.
The new study offers a strong hint that dietary vitamin E may
also protect against bladder cancer, which kills about 12,500
Americans annually and is four times more common in men than
women.
The study was based on questionnaires of the eating habits of
about 1,000 Houston residents. Those whose vitamin E intake
was in the top 25 percent had just half as much bladder cancer
as those in the lowest quarter. The actual difference in the
amount of vitamin-rich food the two extremes ate was small,
however, the equivalent of a single daily serving of spinach
or a handful of almonds.
The research was funded largely by the state of Texas. It was
presented by John Radcliffe, a nutrition researcher from Texas
Woman's University, at a meeting of the American Association
for Cancer Research in Orlando.
The reduction was roughly the same, regardless of whether people
got their vitamin E from food alone or in combination with vitamin
pills.
The team
looked at the two most common forms of vitamin E, called alpha-
and gamma-tocopherol, and found that only the alpha variety
was linked with lower bladder cancer risk. Good sources of
this include almonds, spinach, mustard greens, peppers, sunflower
seeds and a variety of oils, including olive, cotton seed
and canola.
Experts say it is too soon to make any firm recommendations
about vitamin E intake for cancer prevention beyond the usual
advice to eat plenty of vegetables and other plant-based foods.
"People need not be afraid to incorporate nuts and seeds into
their diets," Radcliffe said. "For a long time, dietitians
would not recommend them because they are high in fat. But
half an ounce to an ounce of nuts and seeds daily would not
shoot up someone's calorie levels appreciably."
Researchers would like to tease out which elements of the
diet are especially healthful. Many studies have shown that
people who eat lots of fruits and vegetables have lower risk
of cancer. However, these foods contain more than 100 potentially
helpful vitamins, minerals and other substances, and no one
knows exactly which components do this.
Some wonder whether people who often eat fruits and vegetables
have healthier living habits overall, so their diets might
have little real importance. For now, the best scientists
can do is recommend that people eat five or more servings
daily of a variety of vegetables and fruits.
The strongest evidence of vitamin E's cancer effects comes
from a study several years ago on nearly 30,000 Finnish smokers.
It unexpectedly found those who took alpha-tocopherol pills
lowered their prostate cancer risk by one-third. The same
study shocked researchers by showing that another once high-flying
nutrient, beta carotene, appeared to actually increase their
risk of lung cancer.
A National Cancer Institute study now under way is testing
the effects of 400 milligrams of vitamin E and 200 micrograms
of selenium daily on more than 32,000 men for seven years
to see if they reduce prostate cancer.
Dr. David Alberts, head of cancer prevention at the University
of Arizona, said studies like Radcliffe's "are extremely helpful
in raising a hypothesis. It is very difficult to make a recommendation"
that people take vitamin supplements without a carefully conducted
experiment, like the ongoing prostate cancer study.
The recommended U.S. intake of vitamin E is 15 milligrams
daily, which is roughly the amount in a multivitamin.
Disease
kills 12,500 Americans yearly
