Calcium Seems to Protect Against Colorectal Cancer

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Calcium Seems to Protect Against Colorectal Cancer

http://www.forbes.com/lifestyle/health/feeds/hscout/2004/06/15/hscout519541.html

By Kathleen Doheny

HealthDay Reporter

 

 

TUESDAY, June 15 (HealthDayNews) -- Taking calcium supplements helps

prevent polyps in the colon, a risk factor for colorectal cancer.

 

And the supplements seem to offer the most protection against the advanced

polyps most strongly associated with invasive colorectal cancer, according

to a new study.

 

" In an earlier publication, we showed a reduction in polyps [with calcium

intake], " said Dr. John A. Baron, a professor of medicine at Dartmouth

Medical School, and senior author of the study that appears in the June 16

issue of the Journal of the National Cancer Institute.

 

" There was less than a 20 percent reduction, overall, " he added. " Now, we

find when we look at more advanced [polyps], it is a much more marked

reduction, suggesting that calcium might have a more pronounced effect in

preventing advanced [polyps]. "

 

For advanced polyps, calcium might reduce the risk of colorectal cancer 35

percent to 45 percent, Baron said.

 

An estimated 106,370 new cases of colon cancer and 40,570 cases of rectal

cancer will be diagnosed this year in the United States, according to the

American Cancer Society, and about 56,730 deaths will result.

 

Most colon and rectal cancers begin as a polyp, a growth of tissue into the

center of the colon or rectum. Removing polyps, also known as adenomas,

early may prevent them from becoming cancerous, according to the Cancer

Society.

 

In new the study, Baron's team analyzed data from 913 patients enrolled in

the Calcium Polyp Prevention Study. Patients took either a 1,200 milligram

supplement of calcium or a placebo, and had a follow-up colonoscopy -- an

exam of the colon -- one and four years after they began the calcium therapy.

 

Compared with those on a placebo, people taking calcium supplements had

fewer of all types of polyps. But the protective effect was most pronounced

for the kind of advanced lesions that are most strongly associated with

colon cancer. The risk for advanced polyps was reduced by about 35 percent,

Baron said.

 

While it's not known exactly how the calcium may help prevent the polyps,

researchers speculate that calcium prevents the irritating and

cancer-promoting effect of bile acids and other fats in the bowel.

 

In an accompanying editorial in the journal, Ulrike Peters, now an

assistant faculty member at the Fred Hutchinson Cancer Research Center in

Seattle, but formerly a research fellow at the National Cancer Institute,

writes that the beneficial effects of calcium supplements still have not

been proven. But the protective role of calcium against colon cancer " looks

very promising, " she said.

 

For now, she added, those wanting to reduce their risk of colon cancer

should follow the dietary recommendation for calcium -- 1,200 milligrams a

day for those over 50 years of age, and 1,000 milligrams for those 19 to 50.

 

" We cannot really tell if there is a difference right now between [calcium

from] supplementation and from food, " she said. " That needs further

investigation.

 

Dr. Arthur Schatzkin, lead author of the editorial and chief of the

nutritional epidemiology branch of the NCI, agreed. " For a variety of

health reasons people should try to make sure they are getting adequate

intakes of calcium. " Calcium helps with bone strength, for one thing. But

he cautioned that " ...we haven't proved that calcium prevents colon cancer. "

 

Added Baron: " As always, talk to your doctor. It is really thought that

calcium supplements are safe, but don't think you can take something like

this and forget everything else. Remember, this is just one aspect of what

might be done. "

 

He advised people to get colorectal cancer screening tests, such as

colonoscopies and occult blood testing. " Exercise is probably beneficial, "

he added, in helping to reduce colorectal cancer risk.