The Interactive Effect of Vitamin D3 Supplementation and Vitamin D Receptor Polymorphisms on Obesity, Inflammatory and Metabolic Markers in Overweight Women With Hypovitaminosis D

For the randomized controlled clinical trial (RCT), the first fifty eligible women were assigned to either the vitamin D or placebo group using the block randomization method. Each Vitamin D3 pearl (Zahravi Pharma Co, Tabriz, Iran) contained 50000 IU cholecalciferol and was administered weekly for 12 weeks according to guidelines for treating vitamin D deficiency. Placebo pearls (Zahravi Pharma Co, Tabriz, Iran) had the identical appearance, taste, and smell as the vitamin D pearls and could only be identified by the package code. The placebo pearls were administered similarly. To keep the study double-blinded, an assistant who was not involved in assessments managed the randomization and supplement assignment procedure. Participants were structured to hold their sun exposure and physical activity habits and not take any vitamin supplements during the study. They were also asked to inform the researcher before taking any new medications. All participants were provided with a moderately reduced diet (a reduction of 300 kcal per day) based on their basal weight. The nutrigenetic study investigated 75 eligible women (including the vitamin D group and the last fifty women who entered the study). The nutrigenetic study protocol was the same as that mentioned above for the vitamin D group in the RCT. Compliance was ensured by weekly text messages and voice calls to remind the users of the supplement on the given day. In addition, the supplement and placebo pearls were presented in two visits; once at the baseline visit and then after six weeks. Pearls packs were collected from each subject (at week 6 and week 12) to check if all the pearls were consumed as recommended.

During the first and last visits, anthropometric and laboratory assessments were performed for all subjects. The primary outcomes are improving anthropometric, inflammatory, and metabolic markers of overweight women with hypovitaminosis D.