Table 3.

Summary of published studies on faecal microbiota transplantation performed in patients with non-alcoholic fatty liver disease (NAFLD).

Study	Size	NAFLD Criteria	FMT Type	Main Objective	Secondary Aims
Craven L. 2020 [100]	21 (15 allogenic and 6 autologous)	ASSLD guideline 2018	Endoscope to a distal duodenum (2 g of stool), 3:1 allogenic vs. autologous	No significant decrease in the IR measured by HOMA-IR at six months after FMT	No difference in the hepatic PDFF 6 months post-transplant. Improvement in small intestinal permeability assessed using the lactulose: mannitol urine test. Lower concentrations of non-sterified fatty acids and a decrease in the total:HDL cholesterol ratio. No differences in cholesterol, HDL, LDL cholesterol, triglycerides and APoB:ApoA1.
Witjes J. 2020 [101]	21 (11 autologous and 10 allogenic)	NAFLD by ultrasound	FMT from lean vegan vs. autologous 3 FMT at 8 weeks interval: first by gastroduodenoscopy and then by nasoduodenal tube	Improvement in necro-inflammation score. Trend toward no worsening of fibrosis but not significant. Liver genes: increase in ARHGAP18 and serine dehydratase; and decreased RECQL5 and SF3B3	GGT and ALT decreased. No difference in duodenal microbiota diversity. No significant changes in faecal microbiota diversity, but more Ruminococcus, Eubacterium hallii, Faecalibacterium, and Prevotella copri. Change in plasma metabolites: increase in amino acids isoleucine and phenylacetylglutamine.
Xue L. 2022 [102]	75 (FMT 47 vs. non-FMT 28)	ASSLD guideline 2018	Oral probiotics vs. FMT colonoscopy (100 g of faeces with 500 mL of 0.9% saline) + 3 enema (a total of 200 mL of fresh bacteria solution)	Balancing gut microbiota (no statistical differences in Chaol Indexes between two groups after FMT); Fat attenuation degrees decreased from 278.3 to 263.9 dB in FMT group and increased in non-FMT	Decreases in Proteobacteria and increase in Bacteroidetes, Firmicutes, Fusobacteria and Actinobacteria. No differences in blood lipid and liver function.

Abbreviations: ASSLD: American Association for the Study of Liver Diseases; NAFLD: Non-alcoholic fatty liver disease; IR: insulin resistance; PDFF: proton density fat fraction; FMT, faecal microbiota transplant; HDL: high-density lipoprotein; LDL: low-density lipoprotein; APoB: apolipoprotein B; APoA1: apolipoprotein A1; T2DM: type 2 diabetes mellitus; GGT: gamma-glutamyltransferase; ALT: alanine aminotransferase; RECQL5: RecQ Like Helicase 5; ARHGAP18, Rho GTPaseActivating Protein 18; SF3B3, Splicing Factor 3b Subunit.