Vitamin d

Vitamin D is essential for healthy bones, but low blood levels of vitamin D have also been linked with higher risks of diabetes. Experts have debated whether low vitamin D status increases the risk of diabetes, or is just a marker of overall poor health. Researchers at Oxford University used Mendelian Randomisation to dissect the causal effect of vitamin D on risk of diabetes. This method uses genetic variants resulting in life-long differences in blood levels of vitamin D that can mimic the effect of a trial of vitamin D supplementation. 

The research involved a combined analysis of genetic variants for vitamin D in 82,000 participants in the China Kadoorie Biobank together with studies from other populations involving a total of 58,000 cases with diabetes and 370,000 controls. The report published in PLoS Medicine this week, by researchers from the Nuffield Department of Population Health and Radcliffe Department of Medicine, led by Professor Robert Clarke, demonstrated that genetically mediated higher blood levels of vitamin D, corresponding to differences achievable by vitamin D supplements, were associated with a 14% lower risk of diabetes. 

The report’s Chief Statistician, Dr Derrick Bennett said “The results of both observational and genetic analyses provide support for a causally protective effect of higher vitamin D status for prevention of type 2 diabetes”. Large trials are currently testing the effects of vitamin D on other health outcomes. Prof Mark McCarthy, Honorary Consultant Physician, Oxford Centre for Diabetes, Endocrinology and Metabolism, said “The results of trials of vitamin D supplementation are required before advocating vitamin D supplements (or food fortification) for prevention of diabetes”.