TABLE 7.
Human studies assessing the association between vitamin B-12 and the gut microbiome1
| First author, year (ref) | Comparison | Alpha-diversity | Beta-diversity | Relative abundance |
|---|---|---|---|---|
| Boran, 2020 (43) | B12 sufficient vs. deficient infants | Not significant (no differences when stratified by age, sex, history of probiotic use, or delivery mode) | Significant clustering when stratified by age among infants at 6 mo (but not 4 or 5 mo) in unweighted UniFrac | Phylum, genus: not significant (no difference when stratified by age, sex, history of probiotic use, delivery mode) |
| B12 concentrations | Not reported | Not reported | Phylum: not significantGenus: higher Blautia,Faecalibacterium,Fusicatenibacter,Lachnospira, and Lachnospiraceae (FNWNL329); lower Bilophilia,Clostridiales (UncAna95), Lawsonella, and Prevotella | |
| Post- vs. pre- B12 intravenous injections | Not significant | No significant clustering | Phylum, genus: not significant | |
| Babakobi, 2020 (41) | Maternal B12 intake | Not reported | Not reported | Family, genus: not significant (infant gut microbiome) |
| Carrothers, 2015 (40) | B12 intake | Higher in quartile 3 (3.0–6.3 μg/d) vs. other quartiles (Simpson evenness) | No clustering by B12 quartiles | Phylum: Higher Proteobacteria among individuals consuming the highest quartile of B12 intake (6.4–18.4 μg/d) compared with the other quartilesGenus: lower Bacteroides; higher Prevotella |
| Gurwara, 2019 (35) | B12 intake | Higher (Shannon index; continuous B12) | Significant clustering above vs. below median B12 intake | Phylum: higher Verrucomicrobia (above vs. below median)Genus: higher Faecalibacterium,Roseburia, Alistipes, Odoribacterium, Dialister, Akkermansia, Haemophilus; and lower Erysipelatoclostridium,Bacteroides,Lachnospiraceae (UncO8895), Lachnoclostridium (above vs. below median)Genus: higher Faecalibacterium,Akkermansia,Haemophilus, and lower Bacteroides and Lachnospiraceae (Unc94789) (continuous B12)Genus: higher Faecalibacterium, Dialister,Roseburia; and lower Erysipelatoclostridium (continuous B12 adjusted for age, ethnicity, smoking status, alcohol consumption, BMI, diabetes, and hypertension) |
| Herman, 2020 (36) | B12 intake | Not significant | No significant clustering | Genus: not significant |
| Mörkl, 2018 (33) | B12 intake (above vs. below median) | Not reported | Not reported | Differentially abundant bacteria: Proteobacteria, Archea, Odoribacteriaceae,ClostridiaDifferentially abundant with B12 below median: Ruminococcaceae |
| Selma-Royo, 2021 (37) | Maternal B12 intake | Not reported | Not reported | Higher in infants: Klebsiella, Bifidobacteria, Streptococcus, Enterococcus, Dorea,Faecalibacterium, Agathabacter |
| Seura, 2017 (38) | B12 intake | Not reported | Not reported | Not significant |
| Shah, 2017 (42) | B12 intake | Not reported | Not reported | Phylum: lower Bacteroidetes |
| Tamura, 2017 (34) | B12 intake | Not reported | Not reported | Family: lower Enterobacteriaceae |
| Valentini, 2015 (39) | Changes in B12 concentrations | Not reported | Not reported | Increased Bifidobacteria concentration among participants with low-grade inflammation (r = 0.663, P = 0.001) but not significant among participants without inflammation (r = 0.068, P = 0.682) |
1
B12, vitamin B-12; ref, reference.