Table 1.

Differences in gut microbiome composition in AN patients.

References	Cohort and analysis technique	Reported differences in AN compared to healthy controls			Correlations with other parameters:
		Microbiome structure	Microbiome composition	Metabolites
Armougom et al. (11)	n = 9 AN qPCR	N/A	↑M. smithii ↔ Firmicutes ↔ Bacteroidetes ↔Lactobacillus	N/A	BMI negatively correlated with M. smithii
Million et al. (12)	n = 15 AN qPCR	↔ Abundance (total)	↑M. smithii ↑E. coli ↓Lactobacillus reuteri	N/A	BMI: Negatively correlated with M. smithii and E. coli Positively correlated with L. reuteri
Morita et al. (13)	n = 25 (n = 11 AN-BP; n = 14 AN-R) 23S rRNA qPCR Liquid chro matography	↓Abundance (total)	↓ Obligate anaerobes (Costridium coccoides group; Cl. leptum subgroup; Bacteroides fragilis group) ↓Streptococcus ↓Lactobacillus plantarum	↓acetate ↓propionate	AN-R vs. AN-BP (↔ genus and family level) C. difficile only present in AN-BP group ↓Cl.coccoides only in AN-R
Kleiman et al. (14)	n = 15 AN 16S rRNA analysis	↓Richness ↓α Diversity	↑ Bacilli ↑ Coriobacteriales ↑Bifidobacteria ↓ Clostridia ↓ Faecalibacterium ↓ Anaerostipes	N/A	Levels of depression, anxiety and ED psychopathology negatively correlated with α diversity Post-weight gain: ↔α diversity
Mack et al. (15)	n = 55 AN (n = 44 after weight gain) 16S rRNA analysis Gas chromatography	↔ Richness ↔α diversity ↑β diversity ↓α diversity (only in laxative users)	↑ Methanobrevibacter ↑ mucin-degraders (Verrucomicrobia, Bifidobacteria) ↑ Clostridium clusters I, XI, XVIII ↓ Bacteroidetes ↓ Actinobacteria ↓ butyrate producers (Roseburia spp., Gemminger spp.)	↔ SCFAs (total) ↓ butyrate (~Roseburia spp.)	Post-weight gain: ↑β-diversity ↔α diversity Persistent taxonomic differences
Borgo et al. (16)	n = 15 AN 16S rRNA qPCR Gas-liquid chromatography	↔ Richness ↔α diversity ↔β diversity	↑ Proteobacteria ↑ Enterobacteriaceae ↑M. smithii (if detected) ↓ Firmicutes ↓Ruminococcus ↓Clostridium ↓Roseburia	↓ SCFAs (total) ↓propionate ↓ butyrate ↔ isovalerate, isobutyrate	Anxiety and depression severity negatively correlated with butyrate levels BMI negatively correlated with Bacteroides unifiormis
Mörkl et al. (17)	n = 18 AN 16S rRNA	↓Richness ↓α diversity	↑Coriobacteriaceae	N/A	Depression scores negatively correlated with α diversity
Speranza et al. (18)	n = 10 AN Gas chromatography	N/A	N/A	↓propionate ↓ butyrate ↔ acetate	N/A
Hanachi et al. (19)	n = 33 AN (undergoing enteral nutrition) 16S rRNA analysis	↓ Richness ↓α diversity	↑ Enterobacteriaceae ↑Klebsiella, ↑Salmonella ↓ Firmicutes ↓Eubacterium ↓Roseburia	N/A	BMI Positively correlated with Verrucomicrobiaceae, Ruminococcacea Negatively correlated with Clostridiales, Eubacteriaceae
Hata et al. (20)	n = 10 (AN-R) 16S rRNA analysis	N/A	↓Bacteroidetes	N/A	FMT to GF mice led to impaired weight gain + anxiety and compulsive behavior

AN-R, restrictive AN; AN-BP, binge-purging AN; SCFA, short-chain fatty acid; GF, germ-free.