Study design and setting
A triple-blind, parallel-group, single-center RCT will be conducted. The proposed RCT will take place in the Faculty of Nutrition and Food Sciences, Tabriz University of Medical Sciences for eight weeks to see how daily 600mg SB supplementation affects obese people. Figure 1 depicts the study flow chart.
Participants
The study will involve 50 obese individuals. Participants will be both male and female aged 18 to 60 years old; body mass index (BMI) of 30 to 40 kg/m2; Non-inclusion criteria will be included: lack of interest in continuing the study; having diabetes, kidney diseases, heart failure, rheumatic diseases, cancers, liver failure, gastrointestinal disorders; history of obesity surgery; following a weight-loss diet or taking any supplements or weight-loss drugs in the last 6 months; smoking; pregnancy, lactation, or menopause.
Registries and Ethics
Eligible participants will receive the study protocol and sign an informed consent form. This protocol was approved by Ethics Committee of Ahvaz Jundishapur University of Medical Sciences (approval number: IR.AJUMS.REC.1399.845). The research was also registered at the Iranian Registry of Clinical Trials (IRCT20190303042905N2).
Sample size
The sample size was estimated based on serum changes of GLP-1 [28], 95 percent confidence interval, and 80 percent power (α=0.05 and β=0.2). Furthermore, the mean and standard deviation [29] of GLP-1 levels in the study mentioned above were, as follows: Δμ=17.84; SD1=17.93; SD2=22.49. A 20% dropout rate was considered. Lastly, 25 subjects were considered for each group. Individuals who fulfilled the eligibility criteria will be included in the RCT.
Blinding and randomization of participants
All participants will be randomly assigned into two groups (intervention or placebo), stratified by age (two age groups: 18-39 years and 40-60 years) and gender (male and female). The intervention group will receive SB supplementation + hypo-caloric diet (n=25) and placebo group will receive placebo capsule + hypo-caloric diet (n=25). The random block design will be performed by a third person in blocks of two using Random Allocation Software (RAS). Random numbers will be labeled as SB or placebo bottles, and even or odd numbers will be randomly assigned to the study groups. To maintain blindness, instead of A or B, the third person will use specific codes. The bottles will be similar in appearance and weight to achieve blinding. The treatment allocation will be concealed from participants, researchers, and outcome assessors.
Intervention
The intervention group will receive one SB capsule )600 mg( with breakfast for 60 days. The dosage of SB supplementation was determined, based on the previous study [28]. SB supplement (550 mg Butyrate, 50 mg hydroxypropyl methylcellulose, medium-chain triglycerides (MCT), sodium hydroxide, and purified water) will be provided by Body Bio Company (BodyBio, USA). The control group will receive the same amount of placebo capsules for 60 days. Pharmacy Faculty of Tabriz University of Medical Sciences will provide placebo capsules (Tabriz, Iran, containing 600 mg of carboxymethyl cellulose). Size and color of SB capsules and placebo capsules are exactly similar. Both groups will receive SB and placebo capsules every 30 days. The remaining capsules returned by participants will be counted to determine adherence to the supplements in all patients. Adherence will be defined as consuming 90 percent of the supplements.
An expert dietician will design an individualized hypo-caloric diet for each participant. The Mifflin St. Jeor equation will be used to calculate total energy expenditure [30] requirements. Then, 500 kcals of the estimated energy needs will be deducted. The hypo-caloric diet composition will consist of 10-15 percent protein, 25-30 percent fat, and 55-60 percent carbohydrate. Compliance with diet will be checked weekly by phone calls as well as a 3-day food record at the onset and end-point of the study. Figure 2 depicts the schedule for the present study.
Evaluation of diet, physical activity, and appetite
A checklist will be filled out at baseline, which includes demographic data, medical and drug history. For evaluation of dietary intake, the participants will be asked to keep a 3-day (one weekend and two weekdays) food record. Energy and nutrients analysis will be performed using Nutritionist IV (Hearst Corporation, USA). Physical activity level (PAL) will be calculated by the International Physical Activity Questionnaire short form (IPAQ-SF) [31]. To assess appetite, the participants will complete a visual analog scale (VAS) at baseline and end of study [32].
Anthropometric Assessments
Body weight will be measured for subjects wearing minimal clothing (Seca scale) and height will be measured by a wall-mounted meter. To calculate BMI, weight (kg) will be divided by height squared (m2). An accurate measurement of waist circumference will be taken, using a tape meter at the midpoint between the lowest rib and iliac crest at the end of normal expiration. Hip circumference (HC) will be measured at its widest point over the greatest trochanters. Waist/hip ratio (WHR) will also be calculated. Fat-free mass (kg), fat-free mass percent, body fat mass (Kg), and body fat percent, as well as visceral fat will be estimated through MC- 780 TANITA body analyzer (Tanita, Amsterdam, The Netherlands).
Biochemical assays
Five mL venous blood sample will be taken after a 12-h overnight fasting in vacuumed gel separator tubes at baseline and end of the study. Blood samples will be centrifuged at 3000 RPM for 5 minutes to extract the serum. Serum aliquots will be frozen (-80°C) to measure GLP1 (μg/mL) and insulin (μU/mL) using Enzyme-linked immunosorbent assay (ELISA) kits.
Fasting blood sugar (FBS) (mg/dL), triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), aspartate transaminase (AST), alanine transferase (ALT), and Alkaline phosphatase (ALP) will be measured by enzymatic colorimetric kits. The Friedewald equation will be used to compute low-density lipoprotein cholesterol (LDL-C) concentrations. Calculation of the homeostatic model assessment for IR (HOMA-IR) will be done using the following formula: HOMA-IR = [fasting insulin (μIU/mL) × fasting glucose (mg/dL)]/ 405 [33].
Gene expression assay
Five mL of blood samples will be collected in EDTA/K2 tubes. Peripheral blood mononuclear cells (PBMCs) will be isolated using Ficoll-Hypaque density gradient centrifugation. Total RNA extraction will be done using Trizol reagent, according the manufacturer's instruction. After designing primers, the mRNA gene expression of PGC-1α, PPARα, and UCP1 genes will be applied using Real-time polymerase chain reaction (Real time-PCR). In Real time-PCR tests, the housekeeping gene will be β-actin. The fold change of gene expressions will be calculated based on the Livak formula (2–ΔΔCt ) [6].
Outcomes
Primary outcomes will be anthropometrics indices, serum levels of GLP1, gene expression levels of PGC-1α, PPARα, and UCP1. Secondary outcomes consist of lipid profile (serum levels of TG, total cholesterol, HDL-C, and LDL-C), FBS, fasting plasma insulin level, HOMA-IR, ALT, AST, and ALP.
Statistical analysis
Data analysis of the present RCT will be conducted on an intention to treat (ITT) participants. The data will be checked for accuracy and completeness at random intervals. The data will be expressed as means ± SD. For each variable, the percentage change will be calculated, as follows: [(E–B)/B ×100]; E is the end value and B is the baseline value of the variable.
The Kolmogorov-Smirnov test will be used to examine the normality of the data. The paired sample t-test and Independent sample t-test will be performed for the comparison of parametric data within and between groups, respectively. For non-parametric variables, the Mann-Whitney test and Wilcoxon signed rank test will be applied. Confounding factors including baseline values will be controlled using the analysis of covariance (ANCOVA) test. IBM SPSS software (version 21) (Armonk, NY, USA) will be used to analyze the data. A P-value less than 0.05 will be considered a statistically significant.
Adverse effects, safety, and data monitoring
SB supplementation at dosage of 600 mg/day is not known to have any side effect [11]. A Data Monitoring Committee (DMC) will monitor the outcome of the RCT. Furthermore, the report of potential side effects will also be forwarded to the Ethics Committee of Ahvaz University of Medical Sciences.