Study of the effect of vitamin D supplementation on clinical symptoms, parameters of mental health, metabolic profiles, inflammatory factors and biomarkers of oxidative stress in patients with endometriosis

Objective: The aim of this study is to determine the effects of vitamin D supplementation on clinical symptoms, parameters of mental health, metabolic profiles, inflammatory factors and biomarkers of oxidative stress in patients with endometriosis.

Study design: Randomized double-blind placebo-controlled trial. Randomization will be done by the use of computer-generated random numbers. Patients will be assigned into two groups to receive either vitamin D supplement (n=30) or placebo (n=30).

Among patients with endometriosis referred to gynecology and obstetric Clinic affiliated to Iran University of Medical Sciences, 60 patients will be selected according to inclusion and exclusion criteria. Participants, investigators or the assessors of the outcomes are unaware of the study groups. Supplements and placebos are similar in shape and size. Fasting blood samples will be taken at baseline and 12 weeks after the intervention. At the beginning and the end of the intervention: 12 weeks

Inclusion criteria: women with endometriosis aged 18-40. Exclusion criteria: Diabetes mellitus, Thyroid disorders, Hypertension, Hyperprolactinemia, Cushing syndrome.

Intervention group: 50000 IU vitamin D biweekly (Zahravi, Tabriz, Iran), for 12 weeks orally. Control group: vitamin D placebo (Barij essence, Kashan, Iran), every 2 weeks, for 12 weeks orally.

Outcomes: malondialdehyde (primary outcome) and clinical status, mental health status, inflammatory factors, markers of insulin metabolism, lipid profile (secondary outcomes) will be quantified at study baseline and end-of-trial.

To decrease potential confounding effects, all participants will have stratified randomization according to BMI (<25 and ≥25 kg/m2) and age (<30 and ≥30 y). Then, participants in each block will be randomly allocated into two treatment groups to take either supplements or placebo. Randomization will be done by the use of computer software.

Randomization and allocation will be concealed from the researchers and participants until the final analyses are completed. Another person at the gynecology clinic, who is not involved in the trial and not aware of random sequences, will be assigned the participants to the numbered bottles of capsules.