The current study aim was to conduct placebo-controlled randomize clinical trial to assess the short-term efficacy and safety of postbiotics on hepatic fat content as measured by MRI-PDFF and ultrasonography, liver stiffness (LS) measured by Shear Wave Elastography (SWE) and anthropomorphic variables in NAFLD patients.

The study will include 3 periods. Screening period of up to 1 weeks to assess the eligibility to inclusion/exclusion criteria. Treatment period for 3 month where the participants will receive a twice daily oral dose of postbiotics (cell lysate and DNA fragments of the probiotic strain L. rhamnosus DV - NRRLB-68023) at the assigned dose of 100mg or placebo in capsules. During this period monthly phone contacts will be done for assessment of compliance and safety concerns. Follow-up period of up to 3 month.

The scientific literature points to the beneficial properties of probiotics in the process of regulating metabolism, yet at the same time, some scientific papers question the effectiveness and the safety of probiotics. In turn, postbiotics and metabiotics are preparations of inanimate microorganisms and / or their components, which are directly identified with the safety of their use and the health benefits of the host. Due to the chemical structure of postbiotics and metabiotics, it is found that they have many health benefits; in particular, they have a local effect on certain tissues of the intestinal epithelium, and influence on many other organs and tissues. It is postbiotics metabolites and metabiotics structural cell fragments that create the appearance of a therapeutic effect of probiotics, which, in turn, limits the risk of introducing living microorganisms into a weakened immune defence. It should also be pointed out that postbiotics and metabiotics are more stable and have a longer shelf-life.

The practical use of probiotics and the study of the mechanism of their action made lately to find that a certain level of biological activity is preserved by dead probiotic cells and even their lysates, which are the natural mixes of metabiotic and postbiotic substances; a biological activity which is strongly oriented toward gut health and immune system regulation. Because probiotic lysates demonstrated biological activity without any of the potential adverse side effects associated with live bacterial cells, one of the future goal is research of the novel postbiotics and metabiotics substances, their individual structures and biological characteristics for understanding their way of communications with host cells and microbiota representatives.

Considering the high biological activity and safety of postbiotics and metabiotic substances, it can be concluded that such a treatment vector will be promising in the near future. That's why our investigation will concentrate on postbiotic, a supplement containing dry fermented cell lysate and DNA fragments of the probiotic strain L. rhamnosus DV - NRRLB-68023.

Recent scientific animal studies on the stated issues point to the benefits of some postbiotics in treating metabolic disorders. The current study aim was to conduct placebo-controlled randomize clinical trial to assess the short-term efficacy and safety of postbiotics on hepatic fat content as measured by MRI-PDFF and ultrasonography, liver stiffness (LS) measured by Shear Wave Elastography (SWE) and anthropomorphic variables in NAFLD patients.

The study will include 3 periods. Screening period of up to 1 weeks to assess the eligibility to inclusion/exclusion criteria. Treatment period for 3 month where the participants will receive a twice daily oral dose of postbiotics (cell lysate and DNA fragments of the probiotic strain L. rhamnosus DV - NRRLB-68023) at the assigned dose of 100mg or placebo in capsules. All capsules will be identical with similar organoleptic characteristics (e.g., taste and appearance).. Follow-up period of up to 3 month.

The pre-randomization period will be designed to minimize the effects of dietary changes on metabolic markers. For this purpose, 2 weeks before the study start, after inform consent signed, patients were instructed in one-on-one sessions with a dietitian to follow a therapeutic lifestyle-change diet as classified by the NCEP. In addition, participants were instructed to continue with stable anti-hyperglycemic treatment and received standardized mild physical training for 1 hour per day.

Patients who underwent the study were instructed to take the trial medication as prescribed. Throughout the study, weekly phone follow-up visits were provided for assessment of compliance, adherence to the protocol, as well as the recording of adverse events. The effectiveness of therapy was compared and evaluated separately in the two groups.

Inclusion Criteria:

• adult participants (ages 18-70)
• presence of NAFLD diagnosed according to the recommendations of the American Gastroenterology Association (AGA) and American Association for the Study of Liver Disease (AASLD);
• the diagnosis of fatty liver was based on the results of abdominal ultrasonography. Of 4 known criteria (hepato-renal echo contrast, liver brightness, deep attenuation, and vascular blurring), the participants were required to have hepato-renal contrast and liver brightness to be given a diagnosis of NAFLD
• MRI-PDFF of at least 6.4%;
• BMI 25-39.9 kg/m2;
• aspartate transaminase (AST) and alanine transaminase (ALT) ≤3x upper limit of normal;
• written informed consent.

Exclusion Criteria:

• recent hepatitis, or positive screening test for hepatitis B (hepatitis B virus surface antigen) or hepatitis C (hepatitis C antibody);
• alcohol abuse (>20 g/day (2 standard drinks) in women or > 30 g/d (3 drinks) in men over a two-year period);
• drug-induced liver disease, Wilson's disease, hereditary deficiency of antitrypsin-1 and idiopathic hemochromatosis;
• history of decompensated liver disease including ascites, encephalopathy or variceal bleeding;
• regular use of an agents with gut microbiota modulation activity (antibiotic, pro-, pre-, post or synbiotics supplement etc.) within 3 months prior to enrollment;
• allergy on probiotics or their components;
• use of agents such as vitamin E, omega-3 fatty acids or medications with evidence for effects on NAFLD (pioglitazone, GLP-1 analogues, dipeptidyl peptidase IV inhibitors, ursodeoxycholic acid);
• subjects with a history of bariatric surgery or significant weight loss (> 5% body weight) or rapid weight loss (> 1.6kg/week), within 6 months prior to enrollment;
• uncontrolled cardiovascular or respiratory disease, decompensated liver disease including ascites, encephalopathy or variceal bleeding, active malignancy, or chronic infections;
• participant who had severe course of COVID-19 (extracorporeal membrane oxygenation, mechanically ventilated), and/or had a confirmed case of COVID-19 within 4 weeks prior to enrollment;
• participation in other clinical trials;
• presence of pregnancy or lactation.

Randomization was done by the study statistician based on a computer-generated list. The groups were homogeneous according to age, sex and diagnostic criteria. The assignment of groups was blind to participants, research staff and outcome assessors moreover, to maintain blind parallel study the statistician was not aware of the allocation of participants to intervention