A recent study suggests that calcium and vitamin D may not cut colon cancer risk after colonoscopy. The research challenges past studies that had found dietary supplements may help prevent precancerous growths’ recurrence.
Researches reported that they found new cancerous growths in patients that had had them removed in the past despite them taking calcium or vitamin D supplements.
Yet, three other studies had found that calcium supplementation may stave off the disease’s comeback after surgery including a 2007 paper. In that paper, authors wrote that 1,200 mg of calcium per day reduces risk of colon cancer in people at high-risk of colon cancer by 17 percent.
“That was a big surprise. We thought we understood calcium because the data was really quite, quite strong,”
noted Dr. John Baron, the lead author of the study and cancer expert at the University of North Carolina.
Dr. Baron’s study, which was published Sept. 15 in the New England Journal of Medicine, was funded by the National Cancer Institute, while dietary supplements were provided by Pfizer.
During their investigation, researchers sifted through data on 2,259 patients that learned they had precancerous growths called polyps. The polyps were removed through a surgical procedure called colonoscopy.
Study participants were asked to take 1,000 IUs of Vitamin D3 or 1,200 mg of calcium or both. Other volunteers took none. Some women who opted for calcium were given either vitamin D supplements or a placebo. Dr. Baron said that his team did that to involve in the study women who took care of their bone health through calcium supplementation.
The follow-up lasted three years. Study authors reported that between 43 and 45 percent of volunteers were diagnosed with new polyps. That happened despite taking calcium or vitamin D supplementation. The team adjusted results for age, sex, income, substance abuse and other risks and the results were the same: calcium and vitamin D may not cut colon cancer risk.
On the other hand, researchers acknowledged that high doses of vitamin D may prove beneficial, but a new study needs to be conducted. The recently published study used a higher than normal dose of 600 IUs per day or 800 IUs in people aged 70 or over.
Patients at risk of colon cancer also take aspirin to prevent polyps and cancer spread on the long run. But study authors cautioned that high doses of aspirin may case bleeding. So patients should go to their doctors first and have a discussion if they plan to take the pills for an extended period of time.
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