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Folic Acid May Not Avert Colon Cancer

Popular Folic Acid Supplements Don't Lower -- but May Raise -- Cancer Risk, Study Shows

Folic Acid Concern continued...

How could something that is good for babies be bad for grown-ups? It's all a matter of timing, argues an editorial accompanying the folic acid study. Editorial co-author Cornelia M. Ulrich, PhD, of the Fred Hutchinson Cancer Research Center and the University of Washington in Seattle, has studied folic acid for more than a decade.

"What happens is that folate is beneficial when taken when we are young because it decreases genetic mutations," Ulrich tells WebMD. "But as we get older there are more and more abnormalities in the colon -- things like polyps. And at that stage, folic acid probably increases the growth of these abnormalities."

Ulrich notes that the study by Cole, Sandler, and colleagues looked only at people who already had colon polyps removed by colonoscopy before the study began. Such people clearly had abnormalities in the colon. Whether folic acid might prevent cancer in people with normal colons remains an open question, she says.

But who has a normal colon? Nearly all colon cancers occur in people over age 50. Fewer than one in three over-50 adults has had a screening colonoscopy -- still the main way to know for sure whether or not one has polyps.

An estimated 30% of people over age 60 have polyps. And these are the people who might be at risk from taking folic acid supplements.

"Once you are older and have a polyp, there seems no cancer benefit -- and possible harm -- from folic acid," Ulrich says. "People who have had polyps, based on this trial, should not take folic acid."

Sandler says no vitamin or supplement has been proven to prevent cancer.

"The take-home message from our study is people should be cautious about taking supplements to prevent diseases such as cancer because those treatments might be ineffective and could be harmful," he says.

Sandler notes that everyone should get regular screening tests for colon cancer beginning at age 50. Though colonoscopy may be the surest way to know whether you are at risk, different patients may prefer different colon cancer screening tests.

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