Component

Cystathionine

Measured process or biological entity; consult each linked claim for the experimental scope.

7 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 acts on it

  1. Dietary B6 restriction increased plasma cystathionine by 124% while plasma PLP fell from 55.1 to 22.6 nmol/L.

    Vitamin B6 → Cystathionine source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    nutrient_deficiency Imported condition classification; unverified.
    experimental_model
    Nine healthy adults (five women, four men; ages 20–30), controlled restriction with fasting stable-isotope measurements.
    exposure
    Four weeks below 0.5 mg/day dietary B6; overnight-fasted tracer protocol.
    limitations
    Pool size alone cannot identify the limiting enzyme or quantify pathway flux.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    A pathway intermediate accumulated even though the whole pathway did not simply stop.
    primary_references
    [b6-davis2006] Plasma glutathione and cystathionine concentrations are elevated but cysteine flux is unchanged by dietary vitamin B-6 restriction in young men and women (2006). https://pubmed.ncbi.nlm.nih.gov/16424114/ DOI: 10.1093/jn/136.2.373
    tissue_or_cell_type
    Human blood and whole-body measurements
    trigger_kind
    nutrient_deficiency Imported condition classification; unverified.

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1309–1319

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Nine healthy adults (five women, four men; ages 20–30), controlled restriction with fasting stable-isotope measurements. · source_derived_draft · unverified_draft

    ### b6-fasting-cystathionine-pool Dietary B6 restriction increased plasma cystathionine by 124% while plasma PLP fell from 55.1 to 22.6 nmol/L. Condition category: nutrient_deficiency nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: A pathway intermediate accumulated even though the whole pathway did not simply stop. organism: Homo sapiens tissue_or_cell_type: Human blood and whole-body measurements experimental_model: Nine healthy adults (five women, four men; ages 20–30), controlled restriction with fasting stable-isotope measurements. limitations: Pool size alone cannot identify the limiting enzyme or quantify pathway flux. exposure: Four weeks below 0.5 mg/day dietary B6; overnight-fasted tracer protocol. [b6-davis2006] Plasma glutathione and cystathionine concentrations are elevated but cysteine flux is unchanged by dietary vitamin B-6 restriction in young men and women (2006). https://pubmed.ncbi.nlm.nih.gov/16424114/ DOI: 10.1093/jn/136.2.373
    Complete structured claim and evidence

  2. PLP-dependent human CBS condenses serine with homocysteine to produce cystathionine.

    Human cystathionine beta-synthase / CBS → Cystathionine source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    Methionine-derived sulfur enters cysteine synthesis.
    experimental_model
    Recombinant truncated human CBS crystallography
    limitations
    Enzyme chemistry alone does not predict whole-body homocysteine during mild deficiency.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    This B6-dependent step channels homocysteine into transsulfuration.
    primary_references
    [b6-cbs-2001] Structure of human cystathionine beta-synthase: a unique pyridoxal 5'-phosphate-dependent heme protein. (2001). https://pmc.ncbi.nlm.nih.gov/articles/PMC149156/ DOI: 10.1093/emboj/20.15.3910
    tissue_or_cell_type
    Purified recombinant protein; no intact tissue

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 517–527

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant truncated human CBS crystallography · source_derived_draft · unverified_draft

    ### b6-met-cbs-condensation PLP-dependent human CBS condenses serine with homocysteine to produce cystathionine. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: This B6-dependent step channels homocysteine into transsulfuration. organism: Homo sapiens tissue_or_cell_type: Purified recombinant protein; no intact tissue experimental_model: Recombinant truncated human CBS crystallography limitations: Enzyme chemistry alone does not predict whole-body homocysteine during mild deficiency. cross_nutrient: Methionine-derived sulfur enters cysteine synthesis. [b6-cbs-2001] Structure of human cystathionine beta-synthase: a unique pyridoxal 5'-phosphate-dependent heme protein. (2001). https://pmc.ncbi.nlm.nih.gov/articles/PMC149156/ DOI: 10.1093/emboj/20.15.3910
    Complete structured claim and evidence

  3. Human CTH cleaves cystathionine to cysteine, 2-oxobutanoate and ammonia in a PLP-dependent reaction.

    Human cystathionine gamma-lyase / CTH → Cystathionine source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    B6-dependent sulfur transfer supplies cysteine; glutathione synthesis requires additional enzymes.
    experimental_model
    Purified human CTH apo/holo crystal structures and assays
    limitations
    Purified-enzyme evidence does not define dietary requirements or cellular PLP thresholds.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    This step releases cysteine for downstream metabolism.
    primary_references
    [b6-cth-structure-2009] Structural Basis for the Inhibition Mechanism of Human Cystathionine gamma-Lyase, an Enzyme Responsible for the Production of H2S (2009). https://doi.org/10.1074/jbc.M805459200 DOI: 10.1074/jbc.M805459200
    tissue_or_cell_type
    Purified recombinant protein; no intact tissue

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 554–564

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified human CTH apo/holo crystal structures and assays · source_derived_draft · unverified_draft

    ### b6-met-cth-cleavage Human CTH cleaves cystathionine to cysteine, 2-oxobutanoate and ammonia in a PLP-dependent reaction. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: This step releases cysteine for downstream metabolism. organism: Homo sapiens tissue_or_cell_type: Purified recombinant protein; no intact tissue experimental_model: Purified human CTH apo/holo crystal structures and assays limitations: Purified-enzyme evidence does not define dietary requirements or cellular PLP thresholds. cross_nutrient: B6-dependent sulfur transfer supplies cysteine; glutathione synthesis requires additional enzymes. [b6-cth-structure-2009] Structural Basis for the Inhibition Mechanism of Human Cystathionine gamma-Lyase, an Enzyme Responsible for the Production of H2S (2009). https://doi.org/10.1074/jbc.M805459200 DOI: 10.1074/jbc.M805459200
    Complete structured claim and evidence

  4. Cystathionine increased 53% fasting and 76% postprandially; fasting serine increased 12%.

    Vitamin B6 → Cystathionine source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    nutrient_deficiency Imported condition classification; unverified.
    experimental_model
    Twenty-three healthy adults; paired pre/postprandial LC-MS/MS metabolite profiling.
    exposure
    28 days below 0.35 mg/day B6. Related restriction research program; do not count paper totals as independent trial replications.
    limitations
    Shared restriction research program; not an independent demonstration of each molecular enzyme defect.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    More material accumulated at selected points in the network.
    primary_references
    [b6-dasilva2013] Metabolite profile analysis reveals functional effects of 28-day vitamin B-6 restriction on one-carbon metabolism and tryptophan catabolic pathways in healthy men and women (2013). https://pubmed.ncbi.nlm.nih.gov/23966327/ DOI: 10.3945/jn.113.180588
    tissue_or_cell_type
    Human blood and whole-body measurements
    trigger_kind
    nutrient_deficiency Imported condition classification; unverified.

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1449–1459

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Twenty-three healthy adults; paired pre/postprandial LC-MS/MS metabolite profiling. · source_derived_draft · unverified_draft

    ### b6-restriction-serine-cystathionine-profile Cystathionine increased 53% fasting and 76% postprandially; fasting serine increased 12%. Condition category: nutrient_deficiency nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: More material accumulated at selected points in the network. organism: Homo sapiens tissue_or_cell_type: Human blood and whole-body measurements experimental_model: Twenty-three healthy adults; paired pre/postprandial LC-MS/MS metabolite profiling. limitations: Shared restriction research program; not an independent demonstration of each molecular enzyme defect. exposure: 28 days below 0.35 mg/day B6. Related restriction research program; do not count paper totals as independent trial replications. [b6-dasilva2013] Metabolite profile analysis reveals functional effects of 28-day vitamin B-6 restriction on one-carbon metabolism and tryptophan catabolic pathways in healthy men and women (2013). https://pubmed.ncbi.nlm.nih.gov/23966327/ DOI: 10.3945/jn.113.180588
    Complete structured claim and evidence

Where it participates (unsigned role)

  1. Cystathionine fractional synthesis increased by a mean 12% in eight of nine participants; plasma concentration rose 142 to 236 nmol/L.

    Vitamin B6 → Cystathionine fractional synthesis rate source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    nutrient_deficiency Imported condition classification; unverified.
    experimental_model
    Nine healthy adults (five women, four men; ages 20–35), repeated postprandial isotope kinetics.
    exposure
    28 days dietary B6 restriction; plasma PLP49±4 to 19±2 nmol/L.
    limitations
    Fractional synthesis, pool size and total flux are distinct measurements.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    A faster fractional rate for an intermediate can coexist with preserved overall pathway throughput.
    primary_references
    [b6-lamers2011] Moderate vitamin B-6 restriction does not alter postprandial methionine cycle rates of remethylation, transmethylation, and total transsulfuration but increases the fractional synthesis rate of cystathionine in healthy young men and women (2011). https://pubmed.ncbi.nlm.nih.gov/21430249/ DOI: 10.3945/jn.110.134197
    tissue_or_cell_type
    Human blood and whole-body measurements
    trigger_kind
    nutrient_deficiency Imported condition classification; unverified.

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1385–1395

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Nine healthy adults (five women, four men; ages 20–35), repeated postprandial isotope kinetics. · source_derived_draft · unverified_draft

    ### b6-fed-cystathionine-synthesis Cystathionine fractional synthesis increased by a mean 12% in eight of nine participants; plasma concentration rose 142 to 236 nmol/L. Condition category: nutrient_deficiency nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: A faster fractional rate for an intermediate can coexist with preserved overall pathway throughput. organism: Homo sapiens tissue_or_cell_type: Human blood and whole-body measurements experimental_model: Nine healthy adults (five women, four men; ages 20–35), repeated postprandial isotope kinetics. limitations: Fractional synthesis, pool size and total flux are distinct measurements. exposure: 28 days dietary B6 restriction; plasma PLP49±4 to 19±2 nmol/L. [b6-lamers2011] Moderate vitamin B-6 restriction does not alter postprandial methionine cycle rates of remethylation, transmethylation, and total transsulfuration but increases the fractional synthesis rate of cystathionine in healthy young men and women (2011). https://pubmed.ncbi.nlm.nih.gov/21430249/ DOI: 10.3945/jn.110.134197
    Complete structured claim and evidence

  2. Vitamin B6 administration lowered plasma cystathionine in the reported CTH Thr67Ile homozygote.

    Vitamin B6 → Plasma cystathionine concentration source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    machinery_impairment Imported condition classification; unverified.
    evidence_location
    p.Thr67Ile section; Supplemental Table 3
    experimental_model
    Human families; expressed human CTH variants
    exposure
    Vitamin B6 administration reported for patient 2927; observational case context
    limitations
    Single genotype-specific case; not a treatment recommendation or evidence of deficiency.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    B6 responsiveness occurred in this particular enzyme genotype.
    primary_references
    [b6-cth-2009] Cystathionine gamma-lyase: Clinical, metabolic, genetic, and structural studies. (2009). https://pmc.ncbi.nlm.nih.gov/articles/PMC2752209/ DOI: 10.1016/j.ymgme.2009.04.001
    tissue_or_cell_type
    Human plasma
    trigger_kind
    machinery_impairment Imported condition classification; unverified.

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 577–588

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human families; expressed human CTH variants · source_derived_draft · unverified_draft

    ### b6-met-cth-t67i-clinical Vitamin B6 administration lowered plasma cystathionine in the reported CTH Thr67Ile homozygote. Condition category: machinery_impairment nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: B6 responsiveness occurred in this particular enzyme genotype. organism: Homo sapiens tissue_or_cell_type: Human plasma experimental_model: Human families; expressed human CTH variants limitations: Single genotype-specific case; not a treatment recommendation or evidence of deficiency. exposure: Vitamin B6 administration reported for patient 2927; observational case context evidence_location: p.Thr67Ile section; Supplemental Table 3 [b6-cth-2009] Cystathionine gamma-lyase: Clinical, metabolic, genetic, and structural studies. (2009). https://pmc.ncbi.nlm.nih.gov/articles/PMC2752209/ DOI: 10.1016/j.ymgme.2009.04.001
    Complete structured claim and evidence

  3. In the 47-person TT intervention subset, riboflavin increased plasma SAM and cystathionine; no response was detected in the other measured one-carbon metabolites.

    Riboflavin (vitamin B2) → S-Adenosyl-L-methionine source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    machinery_impairment Imported condition classification; unverified.
    cross_nutrient
    B2/MTHFR connects folate-dependent remethylation with methionine-cycle biomarkers.
    experimental_model
    Archived samples from prior BP trials: 115 genotype-characterized adults; TT intervention subset 24 riboflavin and 23 placebo.
    exposure
    1.6 mg/day riboflavin or placebo for 16 weeks; LC-MS/MS plasma metabolites; secondary analysis, not a new independent trial.
    limitations
    Secondary sample analysis of prior BP trials; plasma SAM is not tissue SAM flux, DNA methylation, epigenetic silencing or a proved mediator of BP.
    nutrient_topic
    Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)
    organism
    Homo sapiens
    plain_language
    B2 changed selected circulating methylation-related metabolites; the study did not show that every tissue had been short of methyl groups.
    primary_references
    [b2-robinson2020] Impact of the MTHFR C677T polymorphism on one-carbon metabolites: Evidence from a randomised trial of riboflavin supplementation (2020). https://pubmed.ncbi.nlm.nih.gov/32330571/ DOI: 10.1016/j.biochi.2020.04.004
    tissue_or_cell_type
    Human clinical setting
    trigger_kind
    machinery_impairment Imported condition classification; unverified.

    Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1514–1525

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Archived samples from prior BP trials: 115 genotype-characterized adults; TT intervention subset 24 riboflavin and 23 placebo. · source_derived_draft · unverified_draft

    ### b2-tt-plasma-sam-response In the 47-person TT intervention subset, riboflavin increased plasma SAM and cystathionine; no response was detected in the other measured one-carbon metabolites. Condition category: machinery_impairment nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: B2 changed selected circulating methylation-related metabolites; the study did not show that every tissue had been short of methyl groups. organism: Homo sapiens tissue_or_cell_type: Human clinical setting experimental_model: Archived samples from prior BP trials: 115 genotype-characterized adults; TT intervention subset 24 riboflavin and 23 placebo. limitations: Secondary sample analysis of prior BP trials; plasma SAM is not tissue SAM flux, DNA methylation, epigenetic silencing or a proved mediator of BP. exposure: 1.6 mg/day riboflavin or placebo for 16 weeks; LC-MS/MS plasma metabolites; secondary analysis, not a new independent trial. cross_nutrient: B2/MTHFR connects folate-dependent remethylation with methionine-cycle biomarkers. [b2-robinson2020] Impact of the MTHFR C677T polymorphism on one-carbon metabolites: Evidence from a randomised trial of riboflavin supplementation (2020). https://pubmed.ncbi.nlm.nih.gov/32330571/ DOI: 10.1016/j.biochi.2020.04.004
    Complete structured claim and evidence

In the sources

Preserved passages that mention this component, quoted exactly. Open one to read it in context.

    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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