TABLE 1.
Details of included trials.
| ID | First author, publication year | Country | Studied population | Age (years) | Diagnosis | Study design | Interventions | Sample size | Treatment duration (weeks) | Outcomes |
| 1 | Aller et al. (21) | Spain | Adults, NAFLD | 29–60 | Liver biopsy | Double-blind RCT | Probiotics | 14 | 12 | AST, ALT, BMI, TC, TG, LDL, HDL, FBS, HOMA-IR |
| Placebo | 14 | |||||||||
| 2 | Vajro et al. (43) | Italy | Children, NAFLD | 11 ± 2 | Ultrasound | Pilot double-blind RCT | Probiotics | 10 | 8 | ALT, BMI |
| Placebo | 10 | |||||||||
| 3 | Malaguarnera et al. (22) | Italy | Adults, NASH | 30–65 | Liver biopsy | Double-blind RCT | Synbiotics | 34 | 24 | AST, ALT, BMI, TC, TG, LDL, HDL, FBS, HOMA-IR |
| Placebo | 32 | |||||||||
| 4 | Wong et al. (23) | Hong Kong | Adults, NASH | 18–70 | Liver biopsy | Open-label RCT | Probiotics | 10 | 24 | AST, ALT, BMI, WC, TC, TG, LDL, HDL, FBS |
| Placebo | 10 | |||||||||
| 5 | Alisi et al. (44) | Italy | Children, NAFLD | 6–12 | Liver biopsy | Double-blind RCT | Probiotics | 22 | 16 | ALT, BMI, TG, HOMA-IR |
| Placebo | 22 | |||||||||
| 6 | Eslamparast et al. (24) | Iran | Adults, NAFLD | ≥18 | Fibroscan | Double-blind RCT | Synbiotics | 26 | 28 | AST, ALT, HOMA-IR |
| Placebo | 26 | |||||||||
| 7 | Miccheli et al. (45) | Italy | Children, NAFLD | 6–12 | Ultrasound | Double-blind RCT | Probiotics | 15 | 16 | AST, ALT, BMI, TC, TG, LDL, HDL, FBS, HOMA-IR |
| Placebo | 16 | |||||||||
| 8 | Sepideh et al. (25) | Iran | Adult, NAFLD | 18–65 | Ultrasound | Double-blind RCT | Probiotics | 21 | 8 | FBS, HOMA-IR |
| Placebo | 21 | |||||||||
| 9 | Akbarzadeh et al. (26) | Iran | Adults, NAFLD | 18–77 | Fibroscan | Double-blind RCT | Prebiotics | 38 | 10 | AST, ALT, BMI, WC |
| Placebo | 37 | |||||||||
| 10 | Asgharian et al. (27) | Iran | Adults, NAFLD | 18–60 | Ultrasound | Double-blind RCT | Synbiotics | 38 | 8 | AST, ALT, BMI, WC |
| Placebo | 36 | |||||||||
| 11 | Ekhlasi et al. (28) | Iran | Adults, NAFLD | 25–64 | Ultrasound | Double-blind RCT | Synbiotics | 15 | 8 | AST, ALT, BMI, WC, TC, TG, LDL, HDL, FBS, HOMA-IR |
| Placebo | 15 | |||||||||
| 12 | Ferolla et al. (29) | Brazil | Adults, NASH | 25–74 | Liver biopsy | Double-blind RCT | Synbiotics | 27 | 12 | AST, ALT, BMI, WC, TC, TG, LDL, HDL, FBS |
| Placebo | 23 | |||||||||
| 13 | Asgharian et al. (30) | Iran | Adults, NAFLD | 18–60 | Ultrasound | Double-blind RCT | Synbiotics | 38 | 8 | BMI, WC, TC, TG, LDL, HDL, FBS |
| Placebo | 36 | |||||||||
| 14 | Behrouz et al. (31) | Iran | Adults, NAFLD | 20–60 | Ultrasound | Double-blind RCT | Probiotics | 30 | 12 | BMI, FBS, HOMA-IR |
| Prebiotics | 29 | |||||||||
| Placebo | 30 | |||||||||
| 15 | Famouri et al. (46) | Iran | Children, NAFLD | 10–18 | Ultrasound | Triple-blind RCT | Probiotics | 32 | 12 | AST, ALT, WC, TC, TG, LDL, HDL |
| Placebo | 32 | |||||||||
| 16 | Javadi et al. (32) | Iran | Adults, NAFLD | 20–60 | Ultrasound | Double-blind RCT | Synbiotics | 17 | 12 | AST, ALT, BMI |
| Probiotics | 20 | |||||||||
| Prebiotics | 19 | |||||||||
| Placebo | 19 | |||||||||
| 17 | Javadi et al. (33) | Iran | Adults, NAFLD | 20–60 | Ultrasound | Double-blind RCT | Synbiotics | 17 | 12 | BMI, WC, TC, TG, LDL, HDL, FBS, HOMA-IR |
| Probiotics | 20 | |||||||||
| Prebiotics | 19 | |||||||||
| Placebo | 19 | |||||||||
| 18 | Manzhalii et al. (34) | Ukraine | Adults, NASH | 30–60 | Ultrasound and elevated hepatic enzymes | Non-blinded RCT | Synbiotics | 38 | 12 | AST, ALT, BMI, TC, TG, LDL, FBS |
| Placebo | 37 | |||||||||
| 19 | Mofidi et al. (35) | Iran | Adults, NAFLD | ≥18 | Fibroscan | Double-blind RCT | Synbiotics | 21 | 28 | AST, ALT, TC, TG, LDL, HDL, FBS, HOMA-IR |
| Placebo | 21 | |||||||||
| 20 | Monem et al. (36) | Egypt | Adults, NASH | 44 ± 6 | Liver biopsy | RCT | Probiotics | 15 | 4 | AST, ALT |
| Placebo | 15 | |||||||||
| 21 | Bakhshimoghaddam et al. (37) | Iran | Adults, NAFLD | ≥18 | Ultrasound | Open-label RCT | Synbiotics | 34 | 24 | AST, ALT, HOMA-IR |
| Placebo | 34 | |||||||||
| 22 | Ahn et al. (38) | South Korea | Adults, NAFLD | 19–75 | MRI-PDFF | Double-blind RCT | Probiotics | 30 | 12 | AST, ALT, BMI, TC, TG, HDL, FBS, HOMA-IR |
| Placebo | 35 | |||||||||
| 23 | Duseja et al. (39) | India | Adults, NAFLD | ≥18 | Liver biopsy | Double-blind RCT | Probiotics | 17 | 48 | AST, ALT |
| Placebo | 13 | |||||||||
| 24 | Abhari et al. (40) | Iran | Adults, NAFLD | 18–75 | Fibroscan | Double-blind RCT | Synbiotics | 22 | 12 | AST, ALT, BMI, WC, TC, TG, LDL, HDL, FBS, HOMA-IR |
| Placebo | 24 | |||||||||
| 25 | Behrouz et al. (41) | Iran | Adults, NAFLD | 20–60 | Ultrasound | Double-blind RCT | Probiotics | 30 | 12 | AST, ALT, BMI, WC, TC, TG, LDL, HDL, FBS |
| Prebiotics | 29 | |||||||||
| Placebo | 30 | |||||||||
| 26 | Chong et al. (42) | United Kingdom | Adults, NAFLD | 25–70 | Liver biopsy | Double-blind RCT | Probiotics | 19 | 10 | AST, ALT, TC, TG, LDL, HDL, HOMA-IR |
| Placebo | 16 |
ALT, alanine aminotransferase; AST, aspartate aminotransferase; BMI, body mass index; FBS, fasting blood sugar; HDL, high-density lipoproteins; HOMA-IR, homeostatic model assessment-insulin resistance; LDL, low-density lipoproteins; NAFL, non-alcoholic fatty liver; NASH, non-alcoholic steatohepatitis; MRI-PDFF, proton density fat fraction on magnetic resonance imaging; RCT, randomized controlled trial; TC, total cholesterol; TG, triglycerides; WC, waist circumference.