No indication nutrition helps fight cancer

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

I.P. Freely - 19 Jul 2006 23:48 GMT

From WebMD at
http://health.webmd.com/cgi-bin21/DM/y/eozT0LNg230CBe0omh0E3 :

July 18, 2006 -- Cancer patients spend billions a year on vitamins and
dietary supplements, but there is no proof that these products -- or
other nutrition strategies -- are effective for treating or preventing
the disease, a new analysis shows.

Researchers who reviewed 59 previous studies assessing a wide range of
diet-related approaches found little evidence that specific vitamins,
supplements, or foods had any impact on disease-free survival,
mortality, or cancer recurrence.

The impact of diet on cancer was either disappointing or could not be
determined because most studies conducted to date have been of poor
quality, the researchers concluded.

"There is no evidence that dietary modification by cancer patients
improves survival and benefits disease prognosis," they wrote.

Antibiotics vs. Diet Supplements

The analysis was one of two reports on nutrition and cancer, published
in the July 10 issue of the Journal of the National Cancer Institute.

In an original study from the National Cancer Institute and China's
Peking University, researchers assessed various interventions thought to
prevent stomach cancer or precancerous lesions in Chinese people of
Linqu County in Shandong Province, where stomach cancer causes 42% of
cancer deaths.

The long-time use (around seven years) of either garlic or vitamin E,
vitamin C, and selenium supplements did not result in a reduction in
precancerous lesions or in stomach cancers. But a two-week course of
antibiotics given to kill Helicobacter pylori bacteria in the stomach
was associated with a reduction in precancerous lesions.

H. pylori infection is known to be a major cause of stomach ulcers, and
it is believed to play a critical role in the development of stomach cancer.

Researchers concluded that the H. pylori treatment reduced the
occurrence of precancerous stomach lesions, which could prevent stomach
cancers.

Studies Show No Impact

The analysis of previous nutrition and cancer studies included 25
studies in patients with cancer and 34 studies in patients with
precancerous conditions.

Steven Thomas, MD, PhD, and colleagues from the U.K.'s University of
Bristol concluded that the vast majority of the studies they looked at
were poorly designed or poorly executed.

With this caveat, they reported that none of the interventions studied
appeared to have an impact on cancer one way or the other.

Specifically, vitamin A supplementation did not appear to be beneficial
in studies involving patients with lung, cervical, head and neck, and
skin cancers, and leukemia.

Other studies examined multivitamins use by patients with a variety of
cancers: beta carotene supplementation in patients with skin, stomach,
cervical, mouth, and colorectal cancers; fiber for colorectal cancer;
and green tea for esophageal cancer.

"We did not find any conclusive benefit or harm for any of these
interventions," Thomas tells WebMD.

More Study Needed

But that doesn't mean eating a healthy diet with plenty of fruits and
vegetables is not important for people with cancer or for cancer
survivors, he adds.

"People with cancer are increasingly living longer as medical treatments
improve. We can certainly say that healthy diets are important for
general well-being. But it is more problematic to say that a healthy
diet is beneficial in treating cancer. There is some evidence that this
is the case, but it is not conclusive."

Nutrition and cancer researcher John A. Baron, MD, of Dartmouth Medical
School, tells WebMD that the studies to date have tended to identify
dietary interventions that do not benefit cancer patients.

"We actually do know a lot, but it is mostly about what doesn't work,"
he says. "We now know that antioxidant and fiber supplements are not
protective against colorectal cancer, for example."

In an editorial accompanying the study, Baron wrote that while the
studies examining diet and cancer have tended to be negative, there are
some "hopeful nuggets of progress" in the search for useful diet plans.

He tells WebMD that his own studies strongly suggest that dietary
calcium may help prevent colorectal cancer.

"I do believe that we will have more answers in the near future, but we
do need better studies to give us these answers," he says.

I.P.