{"id":"66a986a5-49a1-5dfd-a544-7df0014ad056","stable_key":"548ab9d6-3a9b-5bed-879c-17d03813b636:b2-gambia-iron-absorption","predicate":"did_not_measurably_change_isotope_absorption","statement":"Stable-isotope iron absorption varied widely within and between Gambian participants and showed no measurable change after riboflavin.","claim_class":"observational","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"d57f0ec6-562f-5ae6-9f32-beed9610f73d","mechanism_event_label":"This human study does not support a blanket claim that B2 always raises iron absorption.","subject":{"id":"86eb1eee-a8d1-539c-8c17-0911f69b6f1b","slug":"riboflavin","display_name":"Riboflavin (vitamin B2)","entity_type_key":"small_molecule"},"object":{"id":"4429d8ae-d732-5f5e-acc1-2c872e23da62","slug":"nonheme-iron-absorption","display_name":"Nonheme iron absorption","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"d57f0ec6-562f-5ae6-9f32-beed9610f73d","stable_key":"548ab9d6-3a9b-5bed-879c-17d03813b636:b2-gambia-iron-absorption-event","event_type":"observed_intervention","label":"This human study does not support a blanket claim that B2 always raises iron absorption.","description":"Stable-isotope iron absorption varied widely within and between Gambian participants and showed no measurable change after riboflavin.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"89bcaf42-b4ab-5760-8c2e-44eace10cee0","slug":"iron","display_name":"Iron","entity_type_key":"nutrient_element"},"role":"test_nutrient","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"86eb1eee-a8d1-539c-8c17-0911f69b6f1b","slug":"riboflavin","display_name":"Riboflavin (vitamin B2)","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"4429d8ae-d732-5f5e-acc1-2c872e23da62","slug":"nonheme-iron-absorption","display_name":"Nonheme iron absorption","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"availability_state","value_text":"nutrient_deficiency","comparator":null,"unit":null,"notes":"Imported condition classification; 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unverified.","entity":null}],"evidence":[{"id":"674835f5-25a1-527b-8e2e-ec8fa61e0421","evidence_kind":"source_excerpt","locator":"Lines 1591-1602","start_line":1591,"end_line":1602,"excerpt":"### b2-gambia-iron-absorption\nStable-isotope iron absorption varied widely within and between Gambian participants and showed no measurable change after riboflavin.\nCondition category: nutrient_deficiency\nnutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: This human study does not support a blanket claim that B2 always raises iron absorption.\norganism: Homo sapiens\ntissue_or_cell_type: Human clinical setting\nexperimental_model: Controlled supplementation study in riboflavin-deficient Gambian men with hemoglobin below 11.5 g/dL; stable-isotope iron absorption.\nlimitations: Measurement variability and study size limit exclusion of smaller effects; rat intestinal findings need separate model labels.\nexposure: Oral riboflavin versus no riboflavin; 3.38 mg 58Fe test dose before and after intervention; treatment dose not inferred from accessed abstract.\ncross_nutrient: Iron-use improvement is distinct from intestinal absorption.\n[b2-fairweather1992] Riboflavin deficiency and iron absorption in adult Gambian men (1992). https://pubmed.ncbi.nlm.nih.gov/1590670/ DOI: 10.1159/000177696","model_system":"Controlled supplementation study in riboflavin-deficient Gambian men with hemoglobin below 11.5 g/dL; stable-isotope iron absorption.","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. 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