Objectives: To assess the molecular effect of vitamin D supplementation separately in Metabolically Healthy Obese (MHO) and Metabolically Unhealthy Obese (MUHO).
Design: Participants are assessed on the basis of Karelis criteria (according to the rate of their triglycerides, HDL-C, LDL-C, insulin sensitivity, and C reactive protein) and divided into MHO (n=75), MUHO (n=75) and Normal-Weight Metabolically Healthy (NWMH) (n=75) groups. In the phase one, MHO and MUHO are compared to NWMH, with respect to the main outcome of the study in a case-control design.
In the phase two, the two obese types are randomly assigned to treatment and placebo groups in a double blind design.
Setting: Main outcome measures are assessed in the phase one, in the above three groups of the study and in the phase two in MHO and MUHO.
Participants: Participants aged 20-48 years, with BMI ≥ 30 kg/m2, and 18.5 ≤ BMI <25 kg/m2 , not taking supplements and not suffering from non-communicable diseases will be invited to participate in the present study.
Intervention: In the phase two, subjects are requested to take one pill (4000 IU vitamin D supplementation or placebo) daily with one of their meals for four months. Compliance monitoring is performed by means of every two-week phone contact and every month clinic visit when calendars showing treatment consumption during the previous month and unused pills are collected and the pills for the next month consumption are distributed among the patients.
Main outcome measures: The metabolomic, biochemical, dietary intake and physical activity assessments