8 weeks of 7000 IU vitamin D was not enough for seniors to improve insulin resistance – July 2012

Effects of vitamin D on insulin resistance in nursing home residents: an interventional study.

Kaviani M, Abdollahian M, Almasi V, Amini M, Yamini AA.
Endokrynol Pol. 2012;63(3):191-5.

Introduction: Insulin resistance is defined as reduction of insulin-stimulated glucose uptake in skeletal muscles and inadequate suppression of the production of endogenous glucose. The aim of this study was to assess the effect of vitamin D intake on insulin resistance in aged patients.

Materials and methods: This interventional study was carried out on residents of Sadeghieh Nursing Home in Iran. The participants were healthy adults aged ? 65.

For eight weeks, the participants took pills containing 50,000 IU vitamin D(3) per week. Insulin resistance was defined as homeostasis model assessment of insulin resistance (HOMA-IR) ? 2.5. We used McNemar's test, Wilcoxon test, chi-square, and Pearson correlation coefficient and SPSS software (v. 12) to analyse the collected data.

Results: The average age of the 76 participants was 78.7 ± 8 years and 52 of the participants were female. Before and after the study, 37 and four participants had vitamin D deficiency, respectively (p ? 0.001). Impaired fasting plasma glucose (FPG) and insulin resistance was not more prevalent in the participants with vitamin D deficiency. In this study, vitamin D intake had no significant effect on FPG level (p = 0.9), but it increased the prevalence of insulin resistance significantly (p ? 0.001).

Conclusions: In our study, before and after the intervention, vitamin D deficiency had no relationship with FPG level and insulin resistance.
Vitamin D intake had no significant effect on FPG level, but it increased the prevalence of insulin resistance significantly.
We believe that performing more studies, with a longer timespan and larger sample size, as double-blind clinical trials, is necessary.

PMID: 22744624
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  1. People in the Middle East have very low levels of vitamin D.
  2. It takes a while to ‘’fill up’’ on vitamin D.
  3. It takes longer if you are very ‘’empty’’
  4. It is likely that vitamin D levels did not exceed 20 nanograms until the sometime in the second month.
  5. Thus there would not have been much time left in the 2 month trial for vitamin D to do any good.

Options for future similar trial

  1. Start with a loading dose phase
  2. Have a longer trial - perhaps 4 months.

See also VitaminDWiki

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