The Effect of the Vitamin D Supplementation in Obese and Non-Diabetic Individuals; a Double Blind Randomized Clinical Trial.

The aim of this study is to determine the effect of vitamin D supplementation on insulin homeostasis including insulin resistancy and β-cell function in healthy overweight and obese adults.

This is a double-blind, parallel-group, placebo-controlled randomized clinical trial with 70 participants in single center in Tehran. In order to randomized the participants in to groups, we will use coin tossing.

This study is performed among patients who will refer from specialized outpatient clinics of Imam Hossein hospital. During the sampling, all of the clients who meet the study criteria are referred to participate in the study. Participants, investigators and outcome assessors are blind in this study.

This study is performed among patients who referred from specialized outpatient clinics of Imam Hossein hospital. During the sampling, all of the clients who meet the study criteria are referred to participate in the study. The inclusion criteria for participants are as follows: 1) age between 18 and 65 years; 2) Body Mass Index (BMI) ≥ 25 kg/m2; 3) serum level of vitamin D < 30 mg/dl.

The intervention group will receive 50000 IU pearl of vitamin D per week for eight weeks, whereas placebo group will receive placebo instead of vitamin D with same dosage and time.

The serum level of fasting blood sugar (FBS), fasting insulin, 1,25 OH vitamin D3, triglyceride (TG), cholesterol (CHL), high-density lipoprotein (HDL) and low-density lipoprotein (LDL), , Homeostasis Model Assessment 2 (HOMA2) for insulin resistance (HOMA2-IR), β-cell function (HOMA2-β) and insulin sensitivity (HOMA2-S)

Randomization method: Simple randomization; Random unit: Individual; Randomization tool: Coin tossing Eligible participants are blindly divided, in a parallel manner (1:1), into two equal groups via simple randomization. For the randomization the groups are named as vitamin D and placebo groups. In order to randomize, no individual is superior to another. Then, the sequence of groups is drawn up by coin tossing. In this method, a random number will be assigned to each participant. Then by coin tossing each number (individual) will be assigned to study groups alternately.

The participants are blind to the treatment (vitamin D or placebo) that they will take. Also, the investigators are blind to the type of treatment which any participant receives. But care providers which are responsible for health of individuals are not blind to the treatment and if any contraindication or problem occurs, they will take suitable actions. Furthermore, outcome assessors and data analyzers are blind to the type of treatments.

All of the data and documents will be published via an article after the end of the study. It should be considered that all of the identity of participants will remain confidential among researchers and no personal information will revealed.

After end of the study. About 3 months after sampling

All of the researchers, scientists and students

All of the data should use for further investigations. All of the researchers, scientists and students can send their request.

sa.ebadi@sbmu.ac.ir

After sending the identification documents the documents will send less than 2 weeks.