{"id":"317897b1-ba8e-55fe-845d-5cbc75885dea","stable_key":"cb568d28-484a-5c2e-9fcc-2d780358e514:c-plasma-dose-sigmoid","predicate":"oral_dose_has_saturable_plasma_response","statement":"Steady-state plasma vitamin C followed a sigmoid dose-response: steepest at 30–100 mg/day, beyond the sigmoid region at 200 mg/day, with complete saturation reported at 1000 mg/day in this cohort.","claim_class":"observational","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"9d2cdf38-eb24-52dc-8643-08eb1c2fc5a5","mechanism_event_label":"Taking more changed the blood level much less once the curve flattened.","subject":{"id":"2047867f-9872-53b2-a553-71c911d0695b","slug":"ascorbic-acid","display_name":"L-Ascorbic acid","entity_type_key":"small_molecule"},"object":{"id":"82e3e6b4-3f0f-5fee-b37f-d076185d7b72","slug":"plasma-ascorbate-concentration","display_name":"Plasma ascorbate concentration","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"9d2cdf38-eb24-52dc-8643-08eb1c2fc5a5","stable_key":"cb568d28-484a-5c2e-9fcc-2d780358e514:c-plasma-dose-sigmoid-event","event_type":"observed_intervention","label":"Taking more changed the blood level much less once the curve flattened.","description":"Steady-state plasma vitamin C followed a sigmoid dose-response: steepest at 30–100 mg/day, beyond the sigmoid region at 200 mg/day, with complete saturation reported at 1000 mg/day in this cohort.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"2047867f-9872-53b2-a553-71c911d0695b","slug":"ascorbic-acid","display_name":"L-Ascorbic acid","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"82e3e6b4-3f0f-5fee-b37f-d076185d7b72","slug":"plasma-ascorbate-concentration","display_name":"Plasma ascorbate concentration","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""}]},"contexts":[{"dimension":"experimental_model","value_text":"Seven healthy volunteers hospitalized for 4–6 months in a controlled depletion/repletion study.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Diet below 5 mg vitamin C/day, followed by seven daily doses spanning 30–2500 mg; separate single-dose bioavailability assessments.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Small controlled cohort; saturation is assay- and endpoint-specific. Historical authors’ RDA and safety proposals are not presented as current universal guidance.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Vitamin C research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"vitamin-c","display_name":"Vitamin C","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Taking more changed the blood level much less once the curve flattened.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[c-levine1996] Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance (1996). https://pubmed.ncbi.nlm.nih.gov/8623000/ DOI: 10.1073/pnas.93.8.3704","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Human blood or whole-person endpoints","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"3567a63f-89b1-529a-b15a-96ed747409e3","evidence_kind":"source_excerpt","locator":"Lines 1397-1407","start_line":1397,"end_line":1407,"excerpt":"### c-plasma-dose-sigmoid\nSteady-state plasma vitamin C followed a sigmoid dose-response: steepest at 30–100 mg/day, beyond the sigmoid region at 200 mg/day, with complete saturation reported at 1000 mg/day in this cohort.\nCondition category: normal\nnutrient_topic: Vitamin C research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Taking more changed the blood level much less once the curve flattened.\norganism: Homo sapiens\ntissue_or_cell_type: Human blood or whole-person endpoints\nexperimental_model: Seven healthy volunteers hospitalized for 4–6 months in a controlled depletion/repletion study.\nlimitations: Small controlled cohort; saturation is assay- and endpoint-specific. Historical authors’ RDA and safety proposals are not presented as current universal guidance.\nexposure: Diet below 5 mg vitamin C/day, followed by seven daily doses spanning 30–2500 mg; separate single-dose bioavailability assessments.\n[c-levine1996] Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance (1996). https://pubmed.ncbi.nlm.nih.gov/8623000/ DOI: 10.1073/pnas.93.8.3704","model_system":"Seven healthy volunteers hospitalized for 4–6 months in a controlled depletion/repletion study.","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [c-levine1996] Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance (1996). https://pubmed.ncbi.nlm.nih.gov/8623000/ DOI: 10.1073/pnas.93.8.3704","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"fa811221-13bd-5c10-adc1-eaf097c7703c","stable_key":"import-cb568d28-484a-5c2e-9fcc-2d780358e514","title":"Vitamin C: mechanisms, deficiency and nutrient interactions (2026-09-17)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text.","file_path":"","sha256":"b7fd83f956abb81855f2ea23199ba14e465cd91f4a2ac560277ec21ddafd7bfc","revision_id":"6cde9bbb-d712-5746-82a6-85b144253efa","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}