Vitamin D is a very common topic at Nutrientology with yet another study supporting the use of vitamin D in those with pre diabetes metabolic syndrome.
The study, published in Clinical Nutrition (December 2011), evaluated 961 people. It suggests that increased blood levels of vitamin D may reduce the risk of developing diabetes. The incidence of type 2 diabetes was almost 8% lower in people with blood levels of vitamin D greater than 18.5 ng/ml, compared with levels lower than 18.5 ng/ml.
These vitamin D researchers believe that vitamin D may reduce the incidence of diabetes by:
- influencing the function of the insulin producing beta-cells found in the pancreas
- affecting insulin sensitivity
- possibly having an anti-inflammatory role.
I have previously posted on vitamin D’s potential anti-diabetic properties in which the authors from Tufts and Harvard Universities concluded, “In adults at risk of type 2 diabetes, short-term supplementation with vitamin D improved β cell function and had a marginal effect on attenuating the rise in HbA1c.”
This new study lasted about 10 years and included 1226 people at the start. 961 of them hung in there and finished. Blood levels of vitamin D and oral glucose tolerance tests were performed at the start of the study (1996-1998), during (2002-2004) and at the end of the study (2005-2007).
Results showed that the incidence of diabetes was less than 5% in people with vitamin D levels greater than 18.5 ng/ml. This compared to an incidence of 12.4% in people with vitamin D levels less than this. In addition, the risk of developing diabetes was significantly lower in people with higher vitamin D levels, and there was no diabetes found in people with blood levels of vitamin D above 30 ng/mL. Based on my review of the research, most support a vitamin D level at or above 30 ng/ml (75 nmol/L) despite the Institute of Medicine’s baseline recommendation of 20 ng/ml (50 nmol/L). Perhaps 20-30 ng/ml is a good range and not borderline low? More research is needed that looks at the various roles that vitamin D plays.
This 18.5 ng/ml is an interesting number. I recently posted on a study that also used this 18.5 ng/ml cutoff in correlation to increased inflammation above this level. The readers of Nutrientology know that correlation does not equal causation, however I feel it is my responsibility to remind new readers to think about this concept.
Our bodies are able to make vitamin D in our skin from exposure to sunshine. Lower vitamin D levels have been observed in northern latitudes that do not experience as much sunshine. The Canadians and northern Europeans have done a lot of research in this area. I have not seen any studies that look at the incidence of diabetes by geographic latitude, but there has been some suggestion in the research that the season of a child’s birth may have some correlation with type 1 diabetes with geographic latitude being a consideration.
Regular Nutrientology readers also know that I often refer to vitamin D as “hormone D” because it is a secosteroid hormone whose effects I believe we are just starting to better understand.
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