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By Vivian Richardson, Ivanhoe Health Correspondent
ORLANDO, Fla. (Ivanhoe Newswire) -- New research reveals folic acid may actually increase a person's risk of developing colon cancer, despite previous research suggesting the nutritional supplement can prevent colon cancer.
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However, study authors write the results apply only to the limited population of this study: men and women who had previously been diagnosed with colorectal adenomas, precursors to most colorectal cancers.
"We were very surprised," study author Bernard Cole, Ph.D., from Dartmouth University in Lebanon, N.H., told Ivanhoe. "We were surprised that folic acid didn't prevent colorectal adenomas and we were very surprised about the suggestions that supplementation might actually enhance the growth of these adenomas."
Previous research, both epidemiological and animal studies, suggested higher folate intake is associated with a decreased risk of colorectal polyps and cancer. Researchers wanted to know if folic acid supplementation could prevent the development of colorectal adenomas in patients at risk for the cancer precursors.
Of patients taking folic acid, 44.1 percent had a new colorectal adenoma at their first follow-up colonoscopy. Only 42.4 percent of the placebo group had an adenoma. At second follow-up, 11.6 percent of the folic acid group had an advanced lesion while just 6.9 percent of the placebo group had an advanced lesion.
Why the folic acid group appeared to have a slightly higher risk of developing adenomas is not clear, though some have proposed that, because the patients in this study were already at high risk of developing an adenoma given their previous diagnoses, they may have had undetected microscopic pre-cancerous lesions at the start of the study. "We can't prove whether that's the case or not because we don't know who had microscopic lesions and who didn't, but it's certainly a very viable hypothesis," said Dr. Cole.
The results of this study cannot be applied to the wider population, Dr. Cole said. Consuming folate or folic acid is still believed to be healthy, though Dr. Cole said patients may want to consider discussing this with their physicians.
Dr. Cole said aspirin, also studied in this project, tended to have a more protective effect. He suggested aspirin may offset any risk generated by folic acid.
Folate is found in vegetables and fruit. Folic acid is a synthetic form of folate and is found in supplement form. Folate is needed to help DNA replicate normally, which may explain why it helps cancer grow. Cancer cells replicate much faster than cells in normal tissue.
This article was reported by Ivanhoe.com, which offers Medical Alerts by e-mail every day of the week. To subscribe, click on: http://www.ivanhoe.com/newsalert/.
SOURCE: The Journal of the American Medical Association, 2007;297:2351-2359
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