Component

Cyanocobalamin

Cyanocobalamin; distinguish intact cobalamin-bound cobalt from free cobalt ion. Independent substance, clinical endpoint or measured readout; study context is retained with each finding.

11 recorded relationships. Experimental role, claim status and evidence remain attached to each record.

Read recorded mechanisms Open recursive mind map

How nutrients influence it

Every nutrient with a recorded effect on this component, credited to the nutrient that acted rather than the chapter that recorded it. Open a nutrient to see the findings and the conditions they were measured under.

How nutrients reach it in more than one step

Chains of two or more recorded steps that end here, grouped by the nutrient they start from. Each step is a separate finding, so a chain is a route a mechanism could take, not proof that it does.

Tracing routes…

What it does

Every recorded relationship this component is part of, grouped by its role. Plain wording comes first; the technical statement follows.

Recorded relationships

What it acts on

  1. The primary posterior tibial CMAP endpoint showed a mean difference of -0.2 mV (95% CI -0.8 to 0.3); secondary nerve-conduction and cognitive outcomes also showed no significant benefit.

    Cyanocobalamin → Posterior tibial compound muscle action potential amplitude source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    biomarker_context Imported condition classification; unverified.
    experimental_model
    Double-blind randomized trial: 201 adults aged at least 75 with B12 107–210 pmol/L, without anemia or relevant neurologic/cognitive signs; 191 had outcome assessment.
    exposure
    Oral cyanocobalamin 1 mg/day versus placebo for 12 months.
    limitations
    Null results have confidence limits; do not extrapolate to symptomatic deficiency.
    nutrient_topic
    Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B12 (cobalamins)
    organism
    Homo sapiens
    plain_language
    Improved B12-related markers did not translate into measured neurologic or cognitive improvement in this asymptomatic group.
    primary_references
    [b12-dangour2015] Effects of vitamin B-12 supplementation on neurologic and cognitive function in older people: a randomized controlled trial (2015). https://pubmed.ncbi.nlm.nih.gov/26135351/ DOI: 10.3945/ajcn.115.110775
    tissue_or_cell_type
    Human blood or whole-person endpoints
    trigger_kind
    biomarker_context Imported condition classification; unverified.

    Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1524–1534

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Double-blind randomized trial: 201 adults aged at least 75 with B12 107–210 pmol/L, without anemia or relevant neurologic/cognitive signs; 191 had outcome assessment. · source_derived_draft · unverified_draft

    ### b12-dangour-neural-null The primary posterior tibial CMAP endpoint showed a mean difference of -0.2 mV (95% CI -0.8 to 0.3); secondary nerve-conduction and cognitive outcomes also showed no significant benefit. Condition category: biomarker_context nutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Improved B12-related markers did not translate into measured neurologic or cognitive improvement in this asymptomatic group. organism: Homo sapiens tissue_or_cell_type: Human blood or whole-person endpoints experimental_model: Double-blind randomized trial: 201 adults aged at least 75 with B12 107–210 pmol/L, without anemia or relevant neurologic/cognitive signs; 191 had outcome assessment. limitations: Null results have confidence limits; do not extrapolate to symptomatic deficiency. exposure: Oral cyanocobalamin 1 mg/day versus placebo for 12 months. [b12-dangour2015] Effects of vitamin B-12 supplementation on neurologic and cognitive function in older people: a randomized controlled trial (2015). https://pubmed.ncbi.nlm.nih.gov/26135351/ DOI: 10.3945/ajcn.115.110775
    Complete structured claim and evidence

  2. Cyanocobalamin increased serum B12 and holotranscobalamin and reduced total homocysteine during the 12-month trial.

    Cyanocobalamin → Serum cobalamin concentration source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    biomarker_context Imported condition classification; unverified.
    experimental_model
    Double-blind randomized trial: 201 adults aged at least 75 with B12 107–210 pmol/L, without anemia or relevant neurologic/cognitive signs; 191 had outcome assessment.
    exposure
    Oral cyanocobalamin 1 mg/day versus placebo for 12 months.
    limitations
    Blood responses do not establish delivery or functional recovery in every tissue.
    nutrient_topic
    Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B12 (cobalamins)
    organism
    Homo sapiens
    plain_language
    The tablets changed the biochemical measurements.
    primary_references
    [b12-dangour2015] Effects of vitamin B-12 supplementation on neurologic and cognitive function in older people: a randomized controlled trial (2015). https://pubmed.ncbi.nlm.nih.gov/26135351/ DOI: 10.3945/ajcn.115.110775
    tissue_or_cell_type
    Human blood or whole-person endpoints
    trigger_kind
    biomarker_context Imported condition classification; unverified.

    Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1512–1522

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Double-blind randomized trial: 201 adults aged at least 75 with B12 107–210 pmol/L, without anemia or relevant neurologic/cognitive signs; 191 had outcome assessment. · source_derived_draft · unverified_draft

    ### b12-dangour-status-response Cyanocobalamin increased serum B12 and holotranscobalamin and reduced total homocysteine during the 12-month trial. Condition category: biomarker_context nutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The tablets changed the biochemical measurements. organism: Homo sapiens tissue_or_cell_type: Human blood or whole-person endpoints experimental_model: Double-blind randomized trial: 201 adults aged at least 75 with B12 107–210 pmol/L, without anemia or relevant neurologic/cognitive signs; 191 had outcome assessment. limitations: Blood responses do not establish delivery or functional recovery in every tissue. exposure: Oral cyanocobalamin 1 mg/day versus placebo for 12 months. [b12-dangour2015] Effects of vitamin B-12 supplementation on neurologic and cognitive function in older people: a randomized controlled trial (2015). https://pubmed.ncbi.nlm.nih.gov/26135351/ DOI: 10.3945/ajcn.115.110775
    Complete structured claim and evidence

  3. No cognitive benefit accompanied B12 alone or B12 plus folic acid over 24 weeks; memory improvement was greater with placebo than B12 alone (P=0.0036).

    Cyanocobalamin → Neuropsychological test performance source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    biomarker_context Imported condition classification; unverified.
    experimental_model
    Double-blind randomized trial: 195 adults aged at least 70 with mild B12 deficiency.
    exposure
    Cyanocobalamin 1000 micrograms/day, cyanocobalamin 1000 micrograms plus folic acid 400 micrograms/day, or placebo for 24 weeks.
    limitations
    Several tested domains and a short trial; the memory comparison does not prove generalized neurotoxicity.
    nutrient_topic
    Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B12 (cobalamins)
    organism
    Homo sapiens
    plain_language
    Correcting the biochemical shortage was not a general cognitive enhancer in this trial.
    primary_references
    [b12-eussen2006] Effect of oral vitamin B-12 with or without folic acid on cognitive function in older people with mild vitamin B-12 deficiency: a randomized, placebo-controlled trial (2006). https://pubmed.ncbi.nlm.nih.gov/16895884/ DOI: 10.1093/ajcn/84.2.361
    tissue_or_cell_type
    Human blood or whole-person endpoints
    trigger_kind
    biomarker_context Imported condition classification; unverified.

    Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1549–1559

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Double-blind randomized trial: 195 adults aged at least 70 with mild B12 deficiency. · source_derived_draft · unverified_draft

    ### b12-eussen-cognition-boundary No cognitive benefit accompanied B12 alone or B12 plus folic acid over 24 weeks; memory improvement was greater with placebo than B12 alone (P=0.0036). Condition category: biomarker_context nutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Correcting the biochemical shortage was not a general cognitive enhancer in this trial. organism: Homo sapiens tissue_or_cell_type: Human blood or whole-person endpoints experimental_model: Double-blind randomized trial: 195 adults aged at least 70 with mild B12 deficiency. limitations: Several tested domains and a short trial; the memory comparison does not prove generalized neurotoxicity. exposure: Cyanocobalamin 1000 micrograms/day, cyanocobalamin 1000 micrograms plus folic acid 400 micrograms/day, or placebo for 24 weeks. [b12-eussen2006] Effect of oral vitamin B-12 with or without folic acid on cognitive function in older people with mild vitamin B-12 deficiency: a randomized, placebo-controlled trial (2006). https://pubmed.ncbi.nlm.nih.gov/16895884/ DOI: 10.1093/ajcn/84.2.361
    Complete structured claim and evidence

  4. B12 plus folic acid increased red-cell folate and decreased total homocysteine by 36%; B12 treatment corrected mild biochemical deficiency.

    Cyanocobalamin → Homocysteine source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    biomarker_context Imported condition classification; unverified.
    cross_nutrient
    Direct combined B12/folic-acid exposure.
    experimental_model
    Double-blind randomized trial: 195 adults aged at least 70 with mild B12 deficiency.
    exposure
    Cyanocobalamin 1000 micrograms/day, cyanocobalamin 1000 micrograms plus folic acid 400 micrograms/day, or placebo for 24 weeks.
    limitations
    The combined group cannot isolate the contribution of folic acid versus B12.
    nutrient_topic
    Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B12 (cobalamins)
    organism
    Homo sapiens
    plain_language
    The two connected vitamins changed the shared marker.
    primary_references
    [b12-eussen2006] Effect of oral vitamin B-12 with or without folic acid on cognitive function in older people with mild vitamin B-12 deficiency: a randomized, placebo-controlled trial (2006). https://pubmed.ncbi.nlm.nih.gov/16895884/ DOI: 10.1093/ajcn/84.2.361
    tissue_or_cell_type
    Human blood or whole-person endpoints
    trigger_kind
    biomarker_context Imported condition classification; unverified.

    Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1536–1547

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Double-blind randomized trial: 195 adults aged at least 70 with mild B12 deficiency. · source_derived_draft · unverified_draft

    ### b12-eussen-folate-homocysteine B12 plus folic acid increased red-cell folate and decreased total homocysteine by 36%; B12 treatment corrected mild biochemical deficiency. Condition category: biomarker_context nutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The two connected vitamins changed the shared marker. organism: Homo sapiens tissue_or_cell_type: Human blood or whole-person endpoints experimental_model: Double-blind randomized trial: 195 adults aged at least 70 with mild B12 deficiency. limitations: The combined group cannot isolate the contribution of folic acid versus B12. exposure: Cyanocobalamin 1000 micrograms/day, cyanocobalamin 1000 micrograms plus folic acid 400 micrograms/day, or placebo for 24 weeks. cross_nutrient: Direct combined B12/folic-acid exposure. [b12-eussen2006] Effect of oral vitamin B-12 with or without folic acid on cognitive function in older people with mild vitamin B-12 deficiency: a randomized, placebo-controlled trial (2006). https://pubmed.ncbi.nlm.nih.gov/16895884/ DOI: 10.1093/ajcn/84.2.361
    Complete structured claim and evidence

  5. The oral and IM groups showed prompt, indistinguishable improvement in hematologic and neurologic abnormalities.

    Cyanocobalamin → Neurologic recovery following B12 replacement source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    nutrient_deficiency Imported condition classification; unverified.
    experimental_model
    Randomized oral-versus-intramuscular study: 38 allocated; five subsequently identified as folate deficient excluded, leaving 18 oral and 15 injection participants.
    exposure
    Cyanocobalamin 2 mg orally each day for 120 days versus 1 mg IM on days 1, 3, 7, 10, 14, 21, 30, 60 and 90. Unequal cumulative exposures.
    limitations
    Small evaluable groups do not establish equivalence for every severe presentation or rare processing disorder.
    nutrient_topic
    Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B12 (cobalamins)
    organism
    Homo sapiens
    plain_language
    Absorption through the usual food route was not required for every effective replacement regimen in this trial.
    primary_references
    [b12-kuzminski1998] Effective treatment of cobalamin deficiency with oral cobalamin (1998). https://pubmed.ncbi.nlm.nih.gov/9694707/ DOI: 10.1182/blood.v92.4.1191
    tissue_or_cell_type
    Human blood or whole-person endpoints
    trigger_kind
    nutrient_deficiency Imported condition classification; unverified.

    Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1685–1695

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Randomized oral-versus-intramuscular study: 38 allocated; five subsequently identified as folate deficient excluded, leaving 18 oral and 15 injection participants. · source_derived_draft · unverified_draft

    ### b12-oral-im-clinical-response The oral and IM groups showed prompt, indistinguishable improvement in hematologic and neurologic abnormalities. Condition category: nutrient_deficiency nutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Absorption through the usual food route was not required for every effective replacement regimen in this trial. organism: Homo sapiens tissue_or_cell_type: Human blood or whole-person endpoints experimental_model: Randomized oral-versus-intramuscular study: 38 allocated; five subsequently identified as folate deficient excluded, leaving 18 oral and 15 injection participants. limitations: Small evaluable groups do not establish equivalence for every severe presentation or rare processing disorder. exposure: Cyanocobalamin 2 mg orally each day for 120 days versus 1 mg IM on days 1, 3, 7, 10, 14, 21, 30, 60 and 90. Unequal cumulative exposures. [b12-kuzminski1998] Effective treatment of cobalamin deficiency with oral cobalamin (1998). https://pubmed.ncbi.nlm.nih.gov/9694707/ DOI: 10.1182/blood.v92.4.1191
    Complete structured claim and evidence

  6. At four months, mean MMA was 169 nmol/L with oral versus 265 with IM treatment; homocysteine was 10.6 versus 12.2 micromol/L. Oral-group MMA was significantly lower.

    Cyanocobalamin → Methylmalonic acid source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    nutrient_deficiency Imported condition classification; unverified.
    experimental_model
    Randomized oral-versus-intramuscular study: 38 allocated; five subsequently identified as folate deficient excluded, leaving 18 oral and 15 injection participants.
    exposure
    Cyanocobalamin 2 mg orally each day for 120 days versus 1 mg IM on days 1, 3, 7, 10, 14, 21, 30, 60 and 90. Unequal cumulative exposures.
    limitations
    Different cumulative exposures prevent interpreting the result as inherent route superiority.
    nutrient_topic
    Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B12 (cobalamins)
    organism
    Homo sapiens
    plain_language
    The biochemical response was recorded separately from the clinical response.
    primary_references
    [b12-kuzminski1998] Effective treatment of cobalamin deficiency with oral cobalamin (1998). https://pubmed.ncbi.nlm.nih.gov/9694707/ DOI: 10.1182/blood.v92.4.1191
    tissue_or_cell_type
    Human blood or whole-person endpoints
    trigger_kind
    nutrient_deficiency Imported condition classification; unverified.

    Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1697–1707

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Randomized oral-versus-intramuscular study: 38 allocated; five subsequently identified as folate deficient excluded, leaving 18 oral and 15 injection participants. · source_derived_draft · unverified_draft

    ### b12-oral-im-metabolic-response At four months, mean MMA was 169 nmol/L with oral versus 265 with IM treatment; homocysteine was 10.6 versus 12.2 micromol/L. Oral-group MMA was significantly lower. Condition category: nutrient_deficiency nutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The biochemical response was recorded separately from the clinical response. organism: Homo sapiens tissue_or_cell_type: Human blood or whole-person endpoints experimental_model: Randomized oral-versus-intramuscular study: 38 allocated; five subsequently identified as folate deficient excluded, leaving 18 oral and 15 injection participants. limitations: Different cumulative exposures prevent interpreting the result as inherent route superiority. exposure: Cyanocobalamin 2 mg orally each day for 120 days versus 1 mg IM on days 1, 3, 7, 10, 14, 21, 30, 60 and 90. Unequal cumulative exposures. [b12-kuzminski1998] Effective treatment of cobalamin deficiency with oral cobalamin (1998). https://pubmed.ncbi.nlm.nih.gov/9694707/ DOI: 10.1182/blood.v92.4.1191
    Complete structured claim and evidence

What acts on it

  1. Purified human CblC/MMACHC supported GSH-dependent decyanation of cyanocobalamin to cob(II)alamin efficiently under anaerobic conditions; the human reaction was oxygen-sensitive.

    Human MMACHC / cobalamin-processing protein CblC → Cyanocobalamin source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    true
    evidence_location
    Abstract; indexed primary Results summary
    experimental_model
    Purified human MMACHC; oxygen-controlled biochemical assay
    exposure
    GSH and specified B12 form under anaerobic versus aerobic conditions
    limitations
    Abstract-level extraction; stronger aerobic activity of the C. elegans enzyme must not be attributed to human MMACHC.
    nutrient_topic
    Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B12 (cobalamins)
    organism
    Homo sapiens
    plain_language
    Glutathione could supply reducing power, but oxygen strongly affected this human-protein reaction.
    primary_references
    [li-2014-gsh-electron] Glutathione-dependent one-electron transfer reactions catalyzed by a B12 trafficking protein (2014). https://pubmed.ncbi.nlm.nih.gov/24742678/ DOI: 10.1074/jbc.M114.567339
    tissue_or_cell_type
    Cell-free assay

    Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 767–779

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified human MMACHC; oxygen-controlled biochemical assay · source_derived_draft · unverified_draft

    ### b12-human-gsh-decyanation Purified human CblC/MMACHC supported GSH-dependent decyanation of cyanocobalamin to cob(II)alamin efficiently under anaerobic conditions; the human reaction was oxygen-sensitive. Condition category: normal nutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Glutathione could supply reducing power, but oxygen strongly affected this human-protein reaction. organism: Homo sapiens tissue_or_cell_type: Cell-free assay experimental_model: Purified human MMACHC; oxygen-controlled biochemical assay limitations: Abstract-level extraction; stronger aerobic activity of the C. elegans enzyme must not be attributed to human MMACHC. exposure: GSH and specified B12 form under anaerobic versus aerobic conditions cross_nutrient: true evidence_location: Abstract; indexed primary Results summary [li-2014-gsh-electron] Glutathione-dependent one-electron transfer reactions catalyzed by a B12 trafficking protein (2014). https://pubmed.ncbi.nlm.nih.gov/24742678/ DOI: 10.1074/jbc.M114.567339
    Complete structured claim and evidence

  2. Human MMACHC converted bound cyanocobalamin to cob(II)alamin during NADPH-supported reductive decyanation; EPR identified the product in a base-off coordination state.

    Human MMACHC / cobalamin-processing protein CblC → Cyanocobalamin source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    true
    evidence_location
    Results: Figure 4; Materials and Methods: Decyanation of CNCbl
    experimental_model
    Purified human MMACHC with human flavoprotein donor
    exposure
    Anaerobic CNCbl/MMACHC, NADPH and MTRR or NDOR1
    limitations
    Reconstituted biochemical system; establishes reaction capability rather than the quantitatively dominant pathway in living humans.
    nutrient_topic
    Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B12 (cobalamins)
    organism
    Homo sapiens
    plain_language
    Processing removes the cyano group and leaves a reduced B12 intermediate.
    primary_references
    [kim-2008-decyanation] Decyanation of vitamin B12 by a trafficking chaperone (2008). https://pubmed.ncbi.nlm.nih.gov/18779575/ DOI: 10.1073/pnas.0805989105
    tissue_or_cell_type
    Cell-free assay

    Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 669–681

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified human MMACHC with human flavoprotein donor · source_derived_draft · unverified_draft

    ### b12-mmachc-decyanation Human MMACHC converted bound cyanocobalamin to cob(II)alamin during NADPH-supported reductive decyanation; EPR identified the product in a base-off coordination state. Condition category: normal nutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Processing removes the cyano group and leaves a reduced B12 intermediate. organism: Homo sapiens tissue_or_cell_type: Cell-free assay experimental_model: Purified human MMACHC with human flavoprotein donor limitations: Reconstituted biochemical system; establishes reaction capability rather than the quantitatively dominant pathway in living humans. exposure: Anaerobic CNCbl/MMACHC, NADPH and MTRR or NDOR1 cross_nutrient: true evidence_location: Results: Figure 4; Materials and Methods: Decyanation of CNCbl [kim-2008-decyanation] Decyanation of vitamin B12 by a trafficking chaperone (2008). https://pubmed.ncbi.nlm.nih.gov/18779575/ DOI: 10.1073/pnas.0805989105
    Complete structured claim and evidence

  3. Human MMACHC residues 1–244 supported cyanocobalamin decyanation with FMN or FAD plus NADPH, without a separately supplied flavoprotein reductase; reduced FMN also supported the reaction.

    Human MMACHC deltaC38 → Cyanocobalamin source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    machinery_impairment Imported condition classification; unverified.
    cross_nutrient
    true
    evidence_location
    Experimental procedures and Results: CblC Has a Flavin Reductase Fold; Figure 1c
    experimental_model
    Recombinant human MMACHC deltaC38 biochemical assay
    exposure
    30–40 micromolar FMN/FAD with 200 micromolar NADPH, or photoreduced FMN
    limitations
    Engineered truncation and reconstitution; does not establish that riboflavin supplementation rescues MMACHC defects.
    nutrient_topic
    Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B12 (cobalamins)
    organism
    Homo sapiens
    plain_language
    A truncated B12-processing protein could use supplied flavins to carry out this reaction.
    primary_references
    [koutmos-2011-flavin] Structural Basis of Multifunctionality in a Vitamin B12-processing Enzyme (2011). https://pubmed.ncbi.nlm.nih.gov/21697092/ DOI: 10.1074/jbc.M111.261370
    tissue_or_cell_type
    Cell-free assay
    trigger_kind
    machinery_impairment Imported condition classification; unverified.

    Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 753–765

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human MMACHC deltaC38 biochemical assay · source_derived_draft · unverified_draft

    ### b12-mmachc-free-flavin-decyanation Human MMACHC residues 1–244 supported cyanocobalamin decyanation with FMN or FAD plus NADPH, without a separately supplied flavoprotein reductase; reduced FMN also supported the reaction. Condition category: machinery_impairment nutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. plain_language: A truncated B12-processing protein could use supplied flavins to carry out this reaction. organism: Homo sapiens tissue_or_cell_type: Cell-free assay experimental_model: Recombinant human MMACHC deltaC38 biochemical assay limitations: Engineered truncation and reconstitution; does not establish that riboflavin supplementation rescues MMACHC defects. exposure: 30–40 micromolar FMN/FAD with 200 micromolar NADPH, or photoreduced FMN cross_nutrient: true evidence_location: Experimental procedures and Results: CblC Has a Flavin Reductase Fold; Figure 1c [koutmos-2011-flavin] Structural Basis of Multifunctionality in a Vitamin B12-processing Enzyme (2011). https://pubmed.ncbi.nlm.nih.gov/21697092/ DOI: 10.1074/jbc.M111.261370
    Complete structured claim and evidence

Where it participates (unsigned role)

  1. Recombinant human MTRR with NADPH supported MMACHC-bound cyanocobalamin conversion to cob(II)alamin; free cyanocobalamin was not detectably reduced without MMACHC.

    Methionine synthase reductase / MTRR → Human MMACHC / cobalamin-processing protein CblC source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    true
    evidence_location
    Results: Figure 4; Materials and Methods: Decyanation of CNCbl
    experimental_model
    Human purified-protein anaerobic reconstitution
    exposure
    4 micromolar reductase, 20 micromolar MMACHC/CNCbl, 200 micromolar NADPH
    limitations
    Reconstituted biochemical system; establishes reaction capability rather than the quantitatively dominant pathway in living humans.
    nutrient_topic
    Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B12 (cobalamins)
    organism
    Homo sapiens
    plain_language
    This flavoprotein can pass reducing power into B12 processing.
    primary_references
    [kim-2008-decyanation] Decyanation of vitamin B12 by a trafficking chaperone (2008). https://pubmed.ncbi.nlm.nih.gov/18779575/ DOI: 10.1073/pnas.0805989105
    tissue_or_cell_type
    Cell-free assay

    Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 683–695

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human purified-protein anaerobic reconstitution · source_derived_draft · unverified_draft

    ### b12-mtrr-mmachc-electrons Recombinant human MTRR with NADPH supported MMACHC-bound cyanocobalamin conversion to cob(II)alamin; free cyanocobalamin was not detectably reduced without MMACHC. Condition category: normal nutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. plain_language: This flavoprotein can pass reducing power into B12 processing. organism: Homo sapiens tissue_or_cell_type: Cell-free assay experimental_model: Human purified-protein anaerobic reconstitution limitations: Reconstituted biochemical system; establishes reaction capability rather than the quantitatively dominant pathway in living humans. exposure: 4 micromolar reductase, 20 micromolar MMACHC/CNCbl, 200 micromolar NADPH cross_nutrient: true evidence_location: Results: Figure 4; Materials and Methods: Decyanation of CNCbl [kim-2008-decyanation] Decyanation of vitamin B12 by a trafficking chaperone (2008). https://pubmed.ncbi.nlm.nih.gov/18779575/ DOI: 10.1073/pnas.0805989105
    Complete structured claim and evidence

  2. Recombinant human NDOR1/NR1 with NADPH supported MMACHC-bound cyanocobalamin conversion to cob(II)alamin; free cyanocobalamin was not detectably reduced without MMACHC.

    Human NADPH-dependent diflavin oxidoreductase 1 → Human MMACHC / cobalamin-processing protein CblC source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    true
    evidence_location
    Results: Figure 4; Materials and Methods: Decyanation of CNCbl
    experimental_model
    Human purified-protein anaerobic reconstitution
    exposure
    4 micromolar reductase, 20 micromolar MMACHC/CNCbl, 200 micromolar NADPH
    limitations
    Reconstituted biochemical system; establishes reaction capability rather than the quantitatively dominant pathway in living humans.
    nutrient_topic
    Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B12 (cobalamins)
    organism
    Homo sapiens
    plain_language
    This flavoprotein can pass reducing power into B12 processing.
    primary_references
    [kim-2008-decyanation] Decyanation of vitamin B12 by a trafficking chaperone (2008). https://pubmed.ncbi.nlm.nih.gov/18779575/ DOI: 10.1073/pnas.0805989105
    tissue_or_cell_type
    Cell-free assay

    Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 697–709

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human purified-protein anaerobic reconstitution · source_derived_draft · unverified_draft

    ### b12-ndor1-mmachc-electrons Recombinant human NDOR1/NR1 with NADPH supported MMACHC-bound cyanocobalamin conversion to cob(II)alamin; free cyanocobalamin was not detectably reduced without MMACHC. Condition category: normal nutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. plain_language: This flavoprotein can pass reducing power into B12 processing. organism: Homo sapiens tissue_or_cell_type: Cell-free assay experimental_model: Human purified-protein anaerobic reconstitution limitations: Reconstituted biochemical system; establishes reaction capability rather than the quantitatively dominant pathway in living humans. exposure: 4 micromolar reductase, 20 micromolar MMACHC/CNCbl, 200 micromolar NADPH cross_nutrient: true evidence_location: Results: Figure 4; Materials and Methods: Decyanation of CNCbl [kim-2008-decyanation] Decyanation of vitamin B12 by a trafficking chaperone (2008). https://pubmed.ncbi.nlm.nih.gov/18779575/ DOI: 10.1073/pnas.0805989105
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    This is a research prototype built from draft material. It is not medical advice, and its statements still await verification against the original studies.

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