Effects of zinc supplementation on obesity: study protocol for a randomized controlled clinical trial

Background: The prevalence of obesity is escalating alarmingly worldwide, and it is now becoming a rapidly growing epidemic in developing countries. Recent studies have reported that zinc has been implicated in altered lipid markers, insulin resistance and some obesity markers. There is a lack of evidence on zinc as a potential therapeutic agent to reduce weight and improve metabolic parameters in obese adults. The present study is designed to evaluate the effects of zinc supplementation on obese adults in Sri Lanka. Furthermore, we aim to evaluate the effects of zinc supplementation on metabolic parameters in this population. Methods/design: This study will be conducted as a randomized, double-blind, placebo-controlled clinical trial for a period of 3 months at the clinical laboratory, Department of Applied Nutrition, Wayamba University of Sri Lanka to assess the efficacy of daily zinc 20 mg supplementation in obese subjects. There will be a total of 80 subjects, aged between 18-60 years, of both genders, who are obese (body mass index (BMI) >= 25). Subjects will be stratified according to age, gender and BMI and randomly assigned into the test and placebo groups in a 1: 1 ratio. The treatment drug is a capsule containing elemental zinc 20 mg as the active ingredient (as zinc sulphate). The placebo capsule will contain lactose monohydrate. The subjects will receive either zinc capsules or placebo daily for 3 months. The study treatments will be double blinded to both investigator and subject. The visits and the evaluations will be as follows: screening (visit 0), baseline (visit 1) and 3 month (visit 2). The primary outcome will be weight reduction among the obese subjects. Secondary outcome measures include glycaemic status (fasting blood glucose), lipid parameters (total cholesterol, triglyceride levels, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol) and blood pressure. Discussion: The trial protocol will aim to establish the effects of zinc supplementation on weight reduction and metabolic risk parameters among obese subjects.