Researchers at Waseda University in Japan and Shanghai University of Sport in China assessed the effect of one-year vitamin D supplementation on insulin resistance. The researchers published their findings in the journal Nutrition Research.
In this study, which was a secondary analysis of a clinical trial, the researchers hypothesized that increased 25-hydroxyvitamin D (25[OH]D) status after vitamin D supplementation for one year would significantly improve insulin resistance.
Higher circulating 25(OH)D has been associated with a lower prevalence of insulin resistance and Type 2 diabetes.
To test their hypothesis, they recruited 96 healthy Japanese adults, but only 81 of them finished the study.
The participants randomly received either 420 international units (IU) of vitamin D3 or placebo every day for one year.
The researchers measured the participants' fasting insulin, glucose, and other parameters at the beginning of the study and end of the treatment.
They also measured participants' visceral fat area and physical activity.
Results showed that supplementing with vitamin D for a year significantly increased the participants' 25(OH)D and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3).
After vitamin D supplementation, fasting glucose levels and values of homeostasis model assessment of insulin resistance index significantly declined, and the results were independent of physical activity and visceral fat accumulation.
Overall, these findings indicated that one-year vitamin D supplementation effectively improves fasting glucose level and insulin resistance.
Read more studies on the benefits of vitamin D supplementation at VitaminD.news.
Sun X, Cao ZB, Tanisawa K, Ito T, Oshima S, Higuchi M. VITAMIN D SUPPLEMENTATION REDUCES INSULIN RESISTANCE IN JAPANESE ADULTS: A SECONDARY ANALYSIS OF A DOUBLE-BLIND, RANDOMIZED, PLACEBO-CONTROLLED TRIAL. Nutrition Research. October 2016; 36(10): 1121-1129. DOI: 10.1016/j.nutres.2016.07.006