Challenging evidence from earlier studies, which suggest that higher concentrations of vitamin D might prevent type 2 diabetes, a study found that there is no evidence of a causal link between a person's vitamin D levels and type 2 diabetes.
"Our findings suggest that interventions to reduce the risk of type 2 diabetes by increasing concentrations of vitamin D are not currently justified," said Nita Forouhi from the University of Cambridge's school of clinical medicine.
The team examined the link between diabetes risk and vitamin D by assessing the genes that control the levels of vitamin D in blood.
According to Forouhi, observational studies that show a strong and consistent higher risk of type 2 diabetes with lower levels of vitamin D may do so because they have thus far not been able to adequately control for factors such as physical activity levels that may be related both to vitamin D levels and the risk of type 2 diabetes.
"Our findings are in agreement with the results of randomised controlled trials which have generally shown that type 2 diabetes was not prevented in individuals taking vitamin D supplements," researchers concluded.
The paper appeared in the journal Lancet's Diabetes and Endocrinology.