The study – published in Diabetologia – finds a correlation between serum levels of vitamin D3 and subsequent incidence of Type 1 diabetes.
Led by Dr Cedric Garland and colleagues from the University of California, San Diego, USA, the team performed a six year analysis of nearly 2,000 people – finding that higher levels of serum vitamin D3, known as 25-hydroxyvitamin D [25(OH)D], are associated with a lower incidence of the disease.
Therefore a preventative role for vitamin D is suggested.
"Previous studies proposed the existence of an association between vitamin D deficiency and risk of and Type 1 diabetes, but this is the first time that the theory has been tested in a way that provides the dose-response relationship," said Garland.
Garland added that the data suggests a minimum level of 25(OH)D required in the blood for the prevention of around half the cases of type 1 diabetes is 50 nanograms per mililetre (ng/ml).
"While there are a few conditions that influence vitamin D metabolism, for most people, 4000 IU per day of vitamin D3 will be needed to achieve the effective levels," Garland suggested.
The study used samples from of blood serum specimens frozen by the Department of Defense Serum Registry for disease surveillance.
Garland and his team analysed 1000 samples of serum from healthy people who later developed type 1 diabetes and 1000 healthy controls whose blood was sampled on or near the same date but who did not develop type 1 diabetes.
By comparing the serum concentrations of 25(OH)D the team were able to determine the optimal serum level needed to lower an individual's risk of developing type 1 diabetes.
“The risk of insulin-requiring diabetes was 3.5 times higher in individuals with the lowest 25(OH)D concentration compared with those with the highest,” reported the authors.
“Individuals in this study who had serum levels of 25 (OH)D greater than 100 nmol/l had a 70% lower risk of developing insulindependent diabetes than those with levels below 43 nmol/l,” they added.
Based on these results, Garland estimates that the level of serum 25(OH)D needed to prevent half the cases of type 1 diabetes is 50 ng/ml.
"This beneficial effect is present at these intakes only for vitamin D3," cautioned Garland.
"Reliance should not be placed on different forms of vitamin D and mega doses should be avoided, as most of the benefits for prevention of disease are for doses less than 10,000 IU/day," he added.
Volume 55, Issue 12, Pages 3224-3227, doi: 10.1007/s00125-012-2709-8
“Lower prediagnostic serum 25-hydroxyvitamin D concentration is associated with higher risk of insulin-requiring diabetes: a nested case–control study”
Authors: E. D. Gorham, C. F. Garland, A. A. Burgi, S. B. Mohr, K. Zeng, H. Hofflich, J. J. Kim, C. Ricordi