Table 4.

Clinical studies

Study	Sample characteristics	Study design	Intervention	Donor	Measurement	Key findings and conclusions
Cai et al. 2019 [66]	1 female MDD patient, 79 years old	Pre- and post-intervention assessment	Single time FMT via gastroscope	6 year-old grandson	PHQ-9	• Six months after intervention PHQ-9 scores improved.
						• Significant increase in Firmicutes counts and Bacteroides significant reduced
De Clerq et al. 2019 [67]	1 female AN patient, 26 years old	Case report, pre- and post-intervention assessment	Single duodenal FMT	Unrelated female donor with BMI of 25	BMI, caloric intake	• Increase in BMI post-intervention
						• No significant differences in gut microbiota composition after FMT
Huang et al. 2019 [45]	30 (18 M, 12F) refractory IBS patients, Mean age: 44 years old	Pre- and post intervention assessment with 1, 3, and 6 month follow-ups	Two to three FMT procedures (done every other day) via colonoscopy	Healthy volunteers aged 8–35	IBS-QOL, IBS-SSS, GSRS, HAM-A and HAM-D	• Significantly improved GI symptoms and alleviated depression and anxiety as indicated by IBS-QOL, IBS-SSS, GSRS, HAM-A and HAM-D scores, 1 and 3 months post-FMT
						• Increase in Verrucomincrobia and Euryarchaeota at phyla level and increase in Methanobrevibacter and Akkermansia at the genus level, at 1 month after FMT compared to before FMT
Mazzawi et al. [46]	13 (9 M, 4F) IBS patients, Mean age: 32 years old	Open label, pilot study	Single duodenal FMT via gastroscope	Healthy donors, aged 20–42	IBS-SQ, IBS-SSS, EPQ-N-12, and HAD	• Scores of all questionnaires improved significantly at all follow-up time points and lasted up to 28 weeks
						• Patients’ microbiota compositions became more similar to donors after FMT
Mizuno et al. 2017 [44]	10 (7 M, 3F) refractory IBS patients, Mean age: 40.1 years old	Single arm, open label, non-randomized study with 12-week follow-up	Single time FMT via colonoscopy	Healthy relatives in second-degree relationship, Mean age: 52 years	HAM-A, HAM-D	• The HAM-D score significantly improved 4 weeks after FMT but returned to the baseline level at 12 weeks
						• When evaluated with HAM-A, the GI symptoms significantly improved from before FMT to 12 weeks after in responders, but not in non-responders
						• Significant increase in microbial diversity from before treatment to week 4
						• Significant relationship between diversity and response to treatment at week 4 but not before treatment
Xie et al. 2019 [47]	1 male MDD patient with alopecia and GI symptoms, 86 years old	Case report, pre- and post-intervention assessment	Six rounds of FMT via colonoscopy	22-year old healthy male donor	HAM-D	• Improved depressive symptoms
						• Improved appetite and no abdominal pain or distension, increased BMI.
						• Improved hair growth without any hair loss treatments
Kurokawa et al. 2018 [48]	17 (8 M, 9F) IBS patients, Mean age: 43.41	Single arm, non-randomized, open label, observational study	Single time FMT, via colonoscopy	Healthy relatives in second-degree relationship, Mean age: 51.41 years	HAM-D and subscale of sleep-related items, HAM-A, and QIDS	• Significant improvement in HAM-D total and sleep subscale score, HAM-A, and QIDS after FMT, at times even without GI symptoms improvement
						• Significant increase in microbiome diversity after FMT
Johnsen et al. 2020 [49]	85 IBS (non-constipated) patients between 18 and 75 years of age	Double-blind, Randomized Controlled Trial, Parallel group	FMT (frozen or fresh) using health donors or using patient’s own feces, delivered to cecum of IBS patients via colonoscope	Frozen or fresh feces from healthy donors	Fatigue Impact Scale (FIS), IBS-QoL, IBS-SSS	• Clinical effect on QoL and fatigue six months after treatment, with waning effect from six to twelve months,
						• Transient treatmnet effect seen in individuals with other functional disorders.
						• Absence of other self reported functional disorders and presence of depression at baseline is suggested to predict a lasting effect of FMT in QoL and fatigue, respectively