There's no genetic evidence that high levels of vitamin D can prevent type 2 diabetes, a new study says.
Some previous research had suggested that elevated levels of vitamin D might protect people against type 2 diabetes, raising the possibility of a link between vitamin D deficiency and the blood sugar disease.
In this study, British researchers investigated the association between diabetes risk and vitamin D by focusing on genes that control blood levels of vitamin D. They found no connection between different variants of these genes and the risk of developing type 2 diabetes.
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The results were published in The Lancet Diabetes & Endocrinology.
"Our findings suggest that interventions to reduce the risk of type 2 diabetes by increasing concentrations of vitamin D are not currently justified. 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 distorting or confounding factors, such as physical activity levels," study author Dr. Nita Forouhi, of the University of Cambridge's School of Clinical Medicine, said in a journal news release.
Diet and exercise
The findings add to evidence showing that taking vitamin D supplements does not prevent diabetes. The only proven ways to prevent type 2 diabetes are diet and exercise, Forouhi said.
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One expert noted that long-term trials that are still looking at any possible connection should be weighed in the final analysis.
The results "need careful interpretation, and long-term randomized trials of vitamin D supplementation, which are underway, remain important," Dr. Brian Buijsse, from the German Institute of Human Nutrition Potsdam-Rehbruecke in Germany, wrote in an accompanying commentary in the journal.
"The results of an [analysis] of 35 short-term trials, however, do not offer much hope that vitamin D supplementation can be used to prevent type 2 diabetes. The sky is becoming rather clouded for vitamin D in the context of preventing type 2 diabetes," he said.
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Image: Vitamin D from Shutterstock