Effects of a Combination Probiotic on Anthropometric Indicators, Gut Permeability, Inflammation, and Oxidative Stress Status of Underweight Adults: A Study Protocol for a Triple-Blind Randomized Controlled Clinical Trial.

To determine whether weight gain diet with or without Lactobacillus supplementation on anthropometric indices, body composition, gut permeability, inflammatory and oxidative biomarkers in underweight adults aged 18 to 65 years.

A controlled, parallel-group, triple-blind, randomized clinical trial of 100 patients using web-based randomization.

From outpatients with BMI<18.5 referred to Dr.Mohsen Nematy's Nutrition Clinic in Mashhad, Iran, 100 patients will be selected based on inclusion criteria. Participants, assessments, and researchers are unaware of the allocation of the study groups. Supplements and placebos are similar in shape and size. After signing the informed consent, a third party who is blind to the study will give the random allocation sequence, and supplements will be provided to the participants. At the beginning and 8 weeks after the intervention, anthropometric indicators and body composition will be examined by body analyzer (InBody, Korea) and fasting blood samples will be taken from patients.

Among the healthy underweight adults referred to the nutrition clinic affiliated to Mashhad University of Medical Sciences, 100 patients will be selected based on the inclusion criteria. Participants will not be included in the study if they have known diseases which can be heart, kidney, lung, or gland diseases.

The subjects in both groups will receive a weight-gain diet and multivitamin. Patients in the intervention group will use 2 capsules containing 109 CFU/capsule/day Lactobacillus with maltodextrin. In the placebo (control) group, the capsules will contain maltodextrin.

body weight, intestinal permeability (serum zonulin level), inflammation, and oxidative stress status

The expected admission date was modified due to a delay in the budget deposit and preparation of the desired supplement.

Randomization method and description of each method: block Randomization Unit: Individual Randomization tool: sealed envelope Block randomization is performed in order to balance the number of samples assigned to each of the study groups. Web randomization (https://www.sealedenvelope.com) is used for this purpose. The number and characteristics of the participants are entered in the desired position and the individuals are randomly assigned to one of the two intervention and placebo groups.

In this triple-blind study, no participants, principal investigator, physician, observers, data collectors, outcome assessors, and data analysts will be aware that each participant in the study was in the main intervention group (receiving a probiotic supplement) or a placebo (without a probiotic). For blinding the trial, the probiotic capsules and placebo will be identical in appearance, packaging, and labeling. All capsules will be packed and encoded by the company (parsilact Company).

Individually nonidentifiable data of participants will be shared in this study. also, the protocol, results, and statistical analysis of the study will be published in the relevant articles.

Access to data begins 6 months after publication of results.

The unidentifiable personal data of the participants will be made available to other researchers at academic institutions.

The unidentifiable personal data of the participants can only be used for research.

Individually nonidentifiable information of participants can be obtained by sending an email to Dr. Mohsen Nemati (NematyM@mums.ac.ir)

Other researchers in academic institutions can send their requests by email to Dr. Mohsen Nemati. The data will be sent to them after consulting and approving the research team.