Vitamin D Supplements Improve Risk Factors for Diabetes
Many health benefits are credited to vitamin D, and a new study from New Zealand has added another one to the list. Researchers found that supplements of the vitamin may improve insulin resistance and sensitivity, which are risk factors for diabetes.
Insulin resistance is a condition in which a person’s tissues have a reduced response to insulin, a hormone that is secreted by the pancreas to help regulate glucose levels in the body. This resistance causes the body to produce larger quantities of insulin in an attempt to maintain normal levels of glucose in the blood.
In the randomized, controlled, double-blind trial, the results of which were published in the British Journal of Nutrition, the investigators studied 81 South Asian women, ages 23 to 68 years, who had insulin resistance. Half of the women were given 100 micrograms (4,000 IU) of vitamin D3 daily; the other half were given a placebo. The treatment period lasted six months.
At the end of six months, the women who had taken vitamin D showed significant improvement in both insulin resistance and sensitivity compared with those who took placebo. The best results were seen in women who had blood levels of vitamin D in the range of 80 to 119 nanomoles per liter (nmol/L). The Vitamin D Council states that the optimal blood level of vitamin D is at least 125 nmol/L (50 ng/mL), yet most Americans have levels less than 30 ng/mL.
This study follows a recent meta-analysis that showed an association between low intakes of vitamin D, calcium, or dairy products and type 2 diabetes. The authors in the current study note that along with improving insulin resistance and sensitivity, their results indicate the importance of increasing the daily recommended intake of vitamin D. The findings of this study and others highlight the concern that the dietary recommended daily intake values (DRIs) in the United States are too low. Currently the DRIs are 200 IU for adults 19 to 50 years, 400 IU for people 51 to 70, and 600 IU for people older than 70.
Pittas AG et al. Journal of Clinical Endocrinology & Metabolism 92(6): 2017-29