{"id":"3f762cb3-1b89-53e9-b50e-b70bbe13fd3d","stable_key":"a9dd23c6-978a-5755-8bd8-f29bd1fe0cda:nia-clin-urine-2py-restriction","predicate":"low_availability_reduces","statement":"Urinary 2PY below 1.2 mg/day tracked the lowest intake; the urinary 2PY-to-methyl-nicotinamide ratio performed less well than individual metabolite outputs and missed the 10.1-NE/day restriction.","claim_class":"observational","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"aa34c906-2fdb-58ba-b350-17dd9ceb2ad7","mechanism_event_label":"Individual urine measurements were more informative than assuming their ratio was a better marker.","subject":{"id":"dfc664d3-d84d-55ca-afe2-1abbfafd83a7","slug":"niacin","display_name":"Niacin (vitamin B3)","entity_type_key":"nutrient_element"},"object":{"id":"b0935938-b80c-5b63-aed2-1f79971685e1","slug":"urinary-2py-excretion","display_name":"Urinary 2PY excretion","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"aa34c906-2fdb-58ba-b350-17dd9ceb2ad7","stable_key":"a9dd23c6-978a-5755-8bd8-f29bd1fe0cda:nia-clin-urine-2py-restriction-event","event_type":"observed_intervention","label":"Individual urine measurements were more informative than assuming their ratio was a better marker.","description":"Urinary 2PY below 1.2 mg/day tracked the lowest intake; the urinary 2PY-to-methyl-nicotinamide ratio performed less well than individual metabolite outputs and missed the 10.1-NE/day restriction.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"d462430c-2f74-56ad-abf6-d1872c4f83a1","slug":"n1-methyl-2-pyridone-5-carboxamide","display_name":"N1-methyl-2-pyridone-5-carboxamide (2PY)","entity_type_key":"small_molecule"},"role":"measured_metabolite","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"dfc664d3-d84d-55ca-afe2-1abbfafd83a7","slug":"niacin","display_name":"Niacin (vitamin B3)","entity_type_key":"nutrient_element"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"b0935938-b80c-5b63-aed2-1f79971685e1","slug":"urinary-2py-excretion","display_name":"Urinary 2PY excretion","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; unverified.","entity":null},{"dimension":"cross_nutrient","value_text":"N1-methyl-2-pyridone-5-carboxamide (2PY) (measured_metabolite)","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/niacin-clinical-sources/jacob1989.abstract.txt\", \"locator\": \"Indexed primary abstract\", \"file_sha256\": \"749fc69d8d6cb1ba79a0b17e38e9300611713e3939224ba9ac809cef91c7a64c\", \"start_char\": 0, \"end_char\": 1463, \"text_sha256\": \"749fc69d8d6cb1ba79a0b17e38e9300611713e3939224ba9ac809cef91c7a64c\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Controlled metabolic-unit feeding of young men for 11 weeks","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"6.1–32 NE/day; oral nicotinamide test doses","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Small controlled male metabolic-unit study. Erythrocytes are not every tissue; historical adequate intake is not a current recommendation. Jacob and Fu reports may describe related participants and are not counted as independent trials. Historical NMN abbreviation means N1-methylnicotinamide, not nicotinamide mononucleotide. Urinary output is not a universal diagnostic cutoff.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Niacin research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"niacin","display_name":"Niacin (vitamin B3)","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Individual urine measurements were more informative than assuming their ratio was a better marker.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[nia-clin-jacob1989] Biochemical markers for assessment of niacin status in young men: urinary and blood levels of niacin metabolites. (1989). https://pubmed.ncbi.nlm.nih.gov/2522982/ DOI: 10.1093/jn/119.4.591","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Urine and plasma","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"trigger_kind","value_text":"nutrient_deficiency","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null}],"evidence":[{"id":"36caadd0-a329-5fa4-9946-c3f59c83a89b","evidence_kind":"source_excerpt","locator":"Lines 1163-1175","start_line":1163,"end_line":1175,"excerpt":"### nia-clin-urine-2py-restriction\nUrinary 2PY below 1.2 mg/day tracked the lowest intake; the urinary 2PY-to-methyl-nicotinamide ratio performed less well than individual metabolite outputs and missed the 10.1-NE/day restriction.\nCondition category: nutrient_deficiency\nnutrient_topic: Niacin research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Individual urine measurements were more informative than assuming their ratio was a better marker.\norganism: Homo sapiens\ntissue_or_cell_type: Urine and plasma\nexperimental_model: Controlled metabolic-unit feeding of young men for 11 weeks\nlimitations: Small controlled male metabolic-unit study. Erythrocytes are not every tissue; historical adequate intake is not a current recommendation. Jacob and Fu reports may describe related participants and are not counted as independent trials. Historical NMN abbreviation means N1-methylnicotinamide, not nicotinamide mononucleotide. Urinary output is not a universal diagnostic cutoff.\nexposure: 6.1–32 NE/day; oral nicotinamide test doses\ncross_nutrient: N1-methyl-2-pyridone-5-carboxamide (2PY) (measured_metabolite)\nevidence_span: {\"source_cache\": \"artifacts/niacin-clinical-sources/jacob1989.abstract.txt\", \"locator\": \"Indexed primary abstract\", \"file_sha256\": \"749fc69d8d6cb1ba79a0b17e38e9300611713e3939224ba9ac809cef91c7a64c\", \"start_char\": 0, \"end_char\": 1463, \"text_sha256\": \"749fc69d8d6cb1ba79a0b17e38e9300611713e3939224ba9ac809cef91c7a64c\"}\n[nia-clin-jacob1989] Biochemical markers for assessment of niacin status in young men: urinary and blood levels of niacin metabolites. (1989). https://pubmed.ncbi.nlm.nih.gov/2522982/ DOI: 10.1093/jn/119.4.591","model_system":"Controlled metabolic-unit feeding of young men for 11 weeks","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [nia-clin-jacob1989] Biochemical markers for assessment of niacin status in young men: urinary and blood levels of niacin metabolites. (1989). https://pubmed.ncbi.nlm.nih.gov/2522982/ DOI: 10.1093/jn/119.4.591","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"a62b7b5b-786a-57e9-85e9-67c6912a5054","stable_key":"import-a9dd23c6-978a-5755-8bd8-f29bd1fe0cda","title":"Niacin: NAD metabolism, 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. 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