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7 December 2009

Calcium and vit D show promise for colorectal health

Supplements of calcium and vitamin D may promote the health of the cells in the colon and rectum, offering potential protection from tumour development, says a new study.

The mineral-vitamin combination was found to normalise the health of cells in the colon and rectum, according to findings published in Cancer Epidemiology, Biomarkers & Prevention.

Researchers from Emory University, the University of Minnesota, and the National Cancer Institute and the National Institutes of Health conducted a pilot, randomized, double-blind, placebo-controlled, clinical trial in 92 men and women with a history of benign colorectal tumours.

Led by Veronika Fedirko, the researchers randomly assigned the participants to receive daily calcium (2.0 g) and/or vitamin D3 supplements (800 IU), or placebo for six months.

Markers of the health of cells were found to increase by 201, 242, and 25 per cent in the calcium, vitamin D, and calcium plus vitamin D groups relative to the placebo, said the researchers.

“These results indicate that calcium and vitamin D promote colorectal epithelial cell differentiation and may ‘normalize’ the colorectal crypt proliferative zone in sporadic adenoma patients, and support further investigation of calcium and vitamin D as chemopreventive agents against colorectal neoplasms,” wrote Febirko and her co-workers.

A wider view of the science

The potential benefits for the vitamin-mineral combination in relation to colorectal cancer is somewhat controversial, with some studies reporting benefits while others report null results.

Indeed, back in 2006 results from the Women's Health Initiative (WHI) stated that daily supplements of vitamin D and calcium 'had no effect' on the risk of colorectal cancer. The results were questioned however and independent cancer experts said at the time that the claims should be interpreted in the light of the complexities of the study.

Michele Forman and Bernard Levin from the MD Anderson Cancer Center at the University of Texas, noted that the WHI trial had three overlapping components, with 69 per cent of the women enrolled on the Dietary Modification trial, 54 per cent enrolled on the Hormone Therapy trial, and 14 per cent enrolled on both.

"The enrolment in three overlapping trials maximised the participation and size of the WHI trial but created a complex approach with potential confounders for biological interpretation," said Forman and Levin.

Colorectal cancer accounts for nine per cent of new cancer cases every year worldwide. The highest incidence rates are in the developed world, while Asia and Africa have the lowest incidence rates.

It remains one of the most curable cancers if diagnosis is made early.

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