Vitamin D Supplements Have Anti-Diabetes Potential
Lee Swanson Research Update
Supplements of the sunshine vitamin may improve insulin resistance and sensitivity, both of which are risk factors for diabetes, says a new study from New Zealand.
Insulin resistance, whereby insufficient insulin is released to produce a normal glucose response from fat, muscle and liver cells, was significantly lower in women following high-dose vitamin D supplementation, according to results of a randomized, controlled, double-blind trial published in the British Journal of Nutrition.
The optimal effects were observed when blood vitamin D levels were in the range of 80 to 119 nanomoles per liter, said the researchers, "providing further evidence for an increase in the recommended adequate levels."
The new study involved 81 South Asian women with insulin resistance living in New Zealand. The subjects, aged between 23 and 68, were randomly assigned to receive either 100 mcg (4,000 IU) of vitamin D3 or placebo daily for six months.
At the end of the test period, women in the vitamin D group experienced "significant improvements" in both insulin sensitivity and resistance, said the researchers, which was also accompanied by a decrease in fasting insulin levels, compared to placebo.
The greatest improvement in insulin resistance was observed when blood levels of vitamin D, measured as 25-hydroxyvitamin D (25(OH)D)—the non-active “storage” form of the vitamin—were at least 80 nanomoles per liter.
"Improving vitamin D status in insulin-resistant women resulted in improved IR and sensitivity, but no change in insulin secretion," wrote the researchers. "Optimal vitamin D concentrations for reducing IR were shown to be 80 to 119 nmol/l, providing further evidence for an increase in the recommended adequate levels," they concluded.
British Journal of Nutrition Published online ahead of print.