TABLE 5.
Studies assessing association between vitamin B-12 and secondary outcomes1
| First author, year (ref) | Model or population | Comparison | Function | Other outcomes |
|---|---|---|---|---|
| In vitro studies | ||||
| Xu, 2018 (23) | In vitro | CC vs. MC vs. control | Secondary functions: MC and CC promoted lipid, terpenoid, and polyketide metabolism, and degradation of exogenous substances; and inhibited the synthesis of transcription factors and secondary metabolitesTertiary functions: MC and CC promoted pathways for DNA repair and recombinant protein (ko03400) and decreased nitrogen metabolism (ko00910) and starch with sucrose metabolism (ko00500)Tertiary functions: Control group increased ABC transporter (ko02010) pathway | SCFAs: MC was positively correlated with propionate and butyrate in canonical correspondence analysisEnzyme activity2: Control had higher protease activity than MC or CC; amylase activity was more stable in control, protease activity fluctuated more in MC, and cellulase activity fluctuated more in CCSCFAs: MC and CC had higher total SCFAs, while control had higher acetate; propionate decreased in control, increased in MC, and did not change in CC; butyrate was highest in MC on day 1 then decreased, and did not change in control or CC |
| Zheng, 2021 (24) | In vitro | High and low CC supplement (CC-high, CC-low) and CC-enriched spinach (CCspinach-high, CCspinach-low) vs. control; within-group changes | Secondary functions:CC-high: lower glycan biosynthesis and metabolismCCspinach-high: lower enzyme family; higher xenobiotics and metabolism, glycan biosynthesis and metabolism, transport and catabolism, lipid metabolism | SCFAs: CCspinach-low had higher acetate and butyrate vs. other groups |
| Murine studies | ||||
| Kelly, 2019 (25) | C57BL/6 mice (8–16 wk old) | CC vs. control | Not reported | Cecum SCFAs: not significant Transcriptome (IL-1β, IL-6, IL-10, TNF-α, IL-12p70, IFN-γ, mKC): not significantCorrinoid concentrations (cecum): higher cecum cobalamin, MeS-ADE; no difference in cecum Me-ADE or cobinamide |
| Post- vs. pre-CC | Not reported | Corrinoid concentrations (stool): lower fecal Me-ADE, MeS-ADE and ADE; higher cobinamide and cobalamin; no difference in control group | ||
| Lurz, 2020 (27) | C57BL/6 mice age 3 wk | CC high (B12++), medium (B12+), and deficient (B12−) dose, and within-group changes | Not reported | Transcriptome (IL-10, TNF-α): not significant |
| Siddharth, 2017 (29) | Wistar rats | B12 concentrations | Lower K00947 (“none,” metabolism) and K02803 [“PTS system, N-acetylglucosamine-specific IIB component (EC:2.7.1.69),” carbohydrate metabolism] | Proteomics:Higher Notch1, complement factor B, thrombospondin-4, IL-1beta, contactin 1, and melanoma inhibitory activityLower endoplasmic reticulum aminopeptidase 1, alpha S1 casein, chromobox protein homolog 5, proteasome subunit alpha2, nucleoside diphosphate kinase A, IL-17 receptor D, osteoprotegerin ligand/TRANCE, mitochondrial ATP synthase beta-subunit, non-receptor tyrosine kinase c-abl oncogene 1, amnionless, parathyroid hormone, neutral ceramidase, and X-linked ectodysplasin-A2 receptor |
| Zhu, 2019 (26) | Male C57BL/6 mice (10 wk old) | CC vs. MC vs. control | Not significant | Not reported |
| Human studies | ||||
| Mörkl, 2018 (33) | Females (18–40 y), not pregnant or lactating | B12 intake (continuous, above vs. below median) | Not reported | Higher zonulin concentrations in serum (indicator of gut permeability) with higher continuous B12 intake and above vs. below median, but not significant by tertiles of B12 intake |
| Tamura, 2017 (34) | Healthy older adults (65–84 y) | B12 intake | Not reported | Lower quercetin degradation, after 7 h incubation of stool samples with quercetin |
1
ADE, adenine cobamide; B12, vitamin B-12; CC, cyanocobalamin; Me-ADE, 2-methyladenine cobamide; MeS-ADE, 2-methylmercaptoadenine cobamide; MC, methylcobalamin; mKC, murine keratinocyte-derived chemokine; ref, reference; TRANCE, tumor necrosis factor-related activation-induced cytokine.
2
No statistical test reported, based on study authors or systematic review authors interpretation of figures