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The role of vitamin D in preventing cancer is a growing area of interest. A number of studies have shown an inverse relationship between cancer risk and sunlight exposure.
A randomised clinical trial was conducted to measure the effect of vitamin D3 and calcium supplements on the risk of all-type cancer in 2,303 healthy, postmenopausal women whose blood levels of vitamin D were already above the current recommended level.
In total, 1,156 women were allocated to the treatment group, while 1,147 were allocated to placebo.
After four years of follow-up, the researchers noted that a new diagnosis of cancer had been made in 45 women in the treatment group and 64 women who were given placebo.
Reporting in the Journal of the American Medical Association
[1]
(online, 28 March 2017), the researchers conclude that although supplementation decreased the incidence of cancer by 30%, the effect was not statistically significant. They say further research is needed to confirm the role of vitamin D in cancer prevention.
References
[1] Lappe J, Watson P, Travers-Gustafson D et al. Effect of vitamin D and calcium supplementation on cancer incidence in older women: a randomized clinical trial. JAMA 2017;317(12):1234-1243. doi: 10.1001/jama.2017.2115
