Supplemental vitamin D and calcium reduces risk of diabetes
The incidence of type-2 diabetes is lower among women who get adequate calcium and supplement with vitamin D. Researchers used data from the Nurses Health Study, which includes over 83,000 women, to study the relationship of calcium and vitamin D intake to type-2 diabetes.
After 20 years of follow-up, it was concluded that a combined daily intake of over 1,200 mg of calcium and more than 800 IU of vitamin D was associated with a 33 percent lower risk of type-2 diabetes. Interestingly, dietary vitamin D intake did not appear to provide any statistically significant benefit. But the women who supplemented with at least 400 IU of vitamin D had a 13% lower risk of diabetes when compared to those who took less than 100 IU per day. Both dietary and supplemental calcium resulted in decreased risk of type-2 diabetes, and those with overall intakes above 1,200 mg had a 21% lower risk than those who got less than 600 mg per day.
Elevated intakes of calcium and vitamin D, especially from supplements, are significantly associated with lower incidence of type-2 diabetes.
Diabetes Care 29:650-656, 2006
It is well-established that vitamin D deficiency or insufficiency is very common among northern populations. However, there is little information on the prevalence of vitamin D deficiency in southern climates with high sun exposure. A recent study shows that adult residents of southern Arizona are commonly deficient in vitamin D despite living in an area with chronic sun exposure.
Vitamin D insufficiency widespread even in sunny climates
A new study published in the American Journal of Clinical Nutrition determined and analyzed blood vitamin D levels in a group of residents of southern Arizona (statistically representative of the larger population).
Participants were categorized into 4 groups on the basis of serum vitamin D concentrations: <10.0 ng/mL, 10.0 to 19.9 ng/mL, 20.0 to 29.9 ng/mL, and 30.0 ng/mL and over. A level of 30 ng/ml is considered a minimum healthy level, and more optimal levels are at 50 ng/ml or more.
The average vitamin D concentration for the total population was 26 ng/mL. Of 637 participants, 22.3% had vitamin D concentrations >30 ng/mL, 25.4% had concentrations <20 ng/mL, and 2.0% had concentrations <10 ng/mL. Blacks (55.5%) and Hispanics (37.6%) were more likely to have deficient vitamin D concentrations (<20 ng/mL) than were non-Hispanic whites (22.7%). Exposure to sunlight had a greater effect on vitamin D levels in whites than in blacks and Hispanics.
Adult residents of southern Arizona are commonly deficient in vitamin D despite living in an area with chronic sun exposure. Adults with darker skin are particularly at risk for vitamin D insufficiency.
American Journal of Clinical Nutrition, Vol. 87, No. 3, 608-613, March 2008
