The effects of green cardamom on blood glucose indices, lipids, inflammatory factors, paraxonase-1, sirtuin-1, and irisin in patients with nonalcoholic fatty liver disease and obesity: study protocol for a randomized controlled trial

BACKGROUND: The relationship between dietary components and nonalcoholic fatty liver disease (NAFLD) needs to be further investigated. The potential health benefits of cardamom have been found in some studies. Cardamom showed beneficial effect on hepatomegaly, dyslipidemia, and fasting hyperglycemia in animals. However, some adverse effects of cardamom have been reported in animals. No previous human study had been conducted on the effects of cardamom in NAFLD. This study aims to determine the effects of green cardamom (Elettaria cardamomum) supplementation on blood glucose indices, lipids, inflammatory profiles, and liver function, especially by examining irisin, paraxonase-1 (PON1) and sirtuin-1 (Sirt1) in obese patients with NAFLD. METHODS: This trial is to be conducted at the polyclinic of the National Iranian Oil Company (NIOC) Central Hospital, Tehran. Eighty obese patients with NAFLD will be selected according to the eligibility criteria. The NAFLD diagnosis method is ultrasonography. Patients will be randomly divided into two groups by a random-number table (cardamom and placebo groups, two 500-mg capsules, three times/day, taken with meals for 3 months, follow-up monthly). General characteristics, dietary intakes (at the beginning, middle, and end), and physical activity (at the beginning and end) will be assessed using a general, 24-h food recall, and short-form International Physical Activity Questionnaires (IPAQ), respectively. Lifestyle advice will be presented to both groups identically. At the beginning and the end, anthropometrics (weight, height, and waist circumference), blood pressure, extent of fatty liver, and blood biomarkers, including serum glucose indices (fasting blood sugar (FBS)) and insulin (FBI), homeostasis model assessment-insulin resistance (HOMA-IR), Quantitative Insulin Sensitivity Check Index (QUICKI)), lipids (triglyceride (TG), low-density lipoprotein-cholesterol (LDL-c), high-density lipoprotein-cholesterol (HDL-c), total cholesterol (TC)), inflammatory markers (highly sensitive C-reactive protein (hs-CRP), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6)), liver enzymes (alanine transaminase (ALT), aspartate transaminase (AST)), irisin, PON1, and Sirt1, will be determined. DISCUSSION: This trial would be the first to assess the effects of green cardamom on several blood factors, including glucose indices, lipids, inflammatory markers, liver enzymes, irisin, PON1, and Sirt1, and blood pressure and anthropometry in obese patients with NAFLD. Further study of cardamom’s potential in improving NAFLD is suggested. TRIAL REGISTRATION: Iranian Registry of Clinical Trials (IRCT), ID number: IRCT2015121317254N4. Registered on 27 December 2015. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13063-017-1979-3) contains supplementary material, which is available to authorized users.