TABLE 6.
Animal studies assessing the association between vitamin B-12 and the gut microbiome1
| First author, year (ref) | Comparison | Alpha-diversity | Beta-diversity | Relative abundance |
|---|---|---|---|---|
| Murine models | ||||
| Kelly, 2019 (25) | Post- vs. pre- CC supplementation | Chao1, Shannon H, Simpson: not significant | Significant difference at genus level but not phylum level | Bacteroides decreased (2.50% baseline, 0.54% endline) |
| CC vs. control at endline | Chao1, Shannon H, Simpson: not significant | Significant difference | Not reported | |
| Lurz, 2020 (27) | High (B12++), medium (B12+), and deficient (B12−) dose CC, and within-group changes | Shannon index: not significantChao1: not significant | No clustering by B12 diet2 | Genus increased in at least 1 group: increased Parabacteroides,Sutterella,Rikenellaceae unc, Mogibacteriaceae unc (all groups), Bilophila,Prevotella,Mucispirillium,Clostridium (B12 + and B12++), Moryella,Clostridiaceae unc (B12+), Eubacterium (B12++) Genus decreased in at least 1 group: Ruminococcus (all groups), Bacteroides (B12- and B12++), RF32 unc, Clostridiales (B12−), Lachnospiraceae (B12+) |
| Park, 2019 (28) | Control diet (B12 and folate) vs. B12 deficient (folate) | Not reported | No clustering by B12 diet2 | Class: lower Gammaproteobacteria and AlphaproteobacteriaClass: higher Deferribacteres and Actinobacteria |
| Siddharth, 2017 (29) | B12 concentrations | Not reported | Not reported | Genus: higher Lutispora,Adlecreutzia,Papillibacter,Clostridium XIVaGenus: lower Lachnobacterium,Clostridium XIVb, Hydrogenoanaerobacterium, Coprococcus,Suterella |
| Zhu, 2019 (26) | CC vs. MC vs. control | Chao1, Shannon index: higher in control group2 | No clustering by B12 supplement2 | Phylum2: MC vs. CC had higher Firmicutes and Proteobacteria and lower BacteroidetesPhylum2: MC and CC vs. control had higher Firmicutes and lower BacteroidetesGenus2: MC had higher Anaerotruncus (vs. others); CC had higher Oscillospira (vs. others); MC and CC higher Lactobacillus and lower Clostridiaceae unc, Ruminococcus,Barnesiella vs. control |
| Non–murine models | ||||
| Cheng, 2018 (30) | High, medium, or low dose B12 (with low-dose FA) | Diversity decreased for low to high B12 dose for OTUs, ACE, and Chao1 index; diversity was inverted U-shaped (highest for medium B12 dose) based on Simpson and Shannon index2 | Clustering based on diet (UPGMA clustering tree, PCoA): B12-med tended to cluster away from B12-low and B12-high2 | Phylum: B12-med had highest Firmicutes and lowest ProteobacteriaGenera: B12-low had highest Desulfovibrio, B12-med had highest abundance of Bacteroides, B12-high had highest abundance of Barnesiella |
| High-, medium-, or low-dose B12 (with high-dose FA) | Diversity was U-shaped (lowest for medium B12 dose) based on OTU numbers, ACE index, and Chao1; diversity increased from low to high B12 dose based on Simpson and Shannon index2 | Phylum: B12-low had the highest Proteobacteria; B12-med had highest Firmicutes and lowest Proteobacteria; B12-high had highest Bacteroidetes, Cyanobacteria, and VerrucomicrobiaGenera: B12-low and B12-med had the highest Desulfovibrio, B12-low had highest Bacillus, B12-high had highest Alistipes | ||
| Long, 2018 (31) | Increasing doses of B12, from 0 mg/kg (group 1) to 0.025 mg/kg (group 6) | Group 3 had highest diversity and group 5 had lowest diversity based on OTUs, ACE, Chao1, Shannon, and Simpson index2 | Group 1 and 6 clustered together, group 1 and 5 were clustered furthest2 | Class: Bacteroidia (highest in 6; lowest in 2), Clostridium (highest in 4; lowest in 5), Gamma-proteobacteria (highest in 5; lowest in 6), Melainabacteria (highest in 3; lowest in 2), Deferribacteres (highest in 2; lowest in 1 and 6)Family: Bacteroidaceae (highest in 5 vs. 1 and 4; lowest in 4), Ruminococcaceae (highest in 3 vs. 2), Desulfovibrionanceae (highest in 5; lowest in 6), Prevotellaceae (highest in 1 vs. 2 and 4 only), Verrucomicrobiaceae (highest in group 3 vs. group 2)Genus: Bacteroides (highest in 5 vs. 1 and 4; lowest in 4), Desulfovibrio (highest in 5; lowest in 6), Alistipes (highest in 4 vs. 1 and 2), Muscispirillum (highest in 2) |
| Duan, 2021 (32) | Methylmalonic acid concentrations | Not reported | Not reported | Genus: Higher Formosa,Saccharibacteria_norank,Kriegella,Pontibaca,Rhodobacteraceae_unclassified,Rhodopirellula; and Maribacter,Lutimonas,Ruegeria,Gammaproteobactereia Incertae Sedis_uncultured,Flavobacteriaceae_unclassified,Muricauda; and lower Weissella |
1
ACE, abundance-based coverage estimator; B12, vitamin B-12; CC, cyanocobalamin; MC, methylcobalamin; med, medium; OTU, operational taxonomic unit; PCoA, principal coordinates analysis; ref, reference; unc, unclassified; UPGMA, unweighted pair group method with arithmetic mean.
2
No statistical test reported, based on study authors or systematic review authors interpretation of figures.