29 January 2010
The risk of colorectal cancer appears to be reduced in those with higher vitamin D levels, according to European researchers (BMJ, online 21 January 2010).
In a study of more than 520,000 participants, those with the highest levels of vitamin D had a lower risk of colorectal cancer compared with those with lower levels. Even participants with mid-level vitamin D levels had a significantly reduced risk, the authors found.
Previous studies had produced conflicting evidence on the link between vitamin D levels and risk of colorectal cancer, they said.
“Raising very low levels of [vitamin D] to mid-range may protect against colorectal cancer,” the authors said.
However, they believed further trials were needed before public health recommendations for supplementation could be made.
Professor Robert Thomas, chief cancer adviser in the Department of Health in Victoria, agreed. While he said the results were significant, he believed it would be premature to advise supplementation, as the biological significance of vitamin D as a risk indicator for colorectal cancer was not yet clear.
The findings did not vary by sex and were not affected by the season or month the blood was collected. (Exposure to sunlight is the main source of vitamin D for most Australians. When we are exposed to ultraviolet light from the sun, vitamin D is formed in our skin. Some foods also contain vitamin D.)
Last Reviewed: 29 January 2010