{"id":"c2830dd5-79c6-5370-b8c0-666a41de4211","stable_key":"7fc92b9e-9cbf-556e-8719-6b5244625250:b12-abs-calcium-tracer-rescue","predicate":"increases-under-metformin","statement":"Adding calcium 500 mg to metformin 850 mg raised mean tracer bioavailability from 30.8% to 46.4% in seven healthy completers (p=0.003).","claim_class":"observational","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"749ac290-02a0-5ee2-a07c-ac714d8dba13","mechanism_event_label":"Calcium coadministration reversed the tracer reduction in this pilot.","subject":{"id":"8e2a5a1f-cd49-5f28-8611-325266fb78a6","slug":"calcium","display_name":"Calcium","entity_type_key":"nutrient_element"},"object":{"id":"938fee66-3ad1-51e3-ab18-515d6c815d9c","slug":"carbon13-cyanocobalamin-bioavailability","display_name":"Oral carbon-13 cyanocobalamin tracer bioavailability","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"749ac290-02a0-5ee2-a07c-ac714d8dba13","stable_key":"7fc92b9e-9cbf-556e-8719-6b5244625250:b12-abs-calcium-tracer-rescue-event","event_type":"observed_intervention","label":"Calcium coadministration reversed the tracer reduction in this pilot.","description":"Adding calcium 500 mg to metformin 850 mg raised mean tracer bioavailability from 30.8% to 46.4% in seven healthy completers (p=0.003).","status":"provisional","compartment":null,"participants":[{"entity":{"id":"b6d9b937-895d-5e0a-8cc5-0454a0b7d373","slug":"vitamin-b12","display_name":"Vitamin B12 (cobalamins)","entity_type_key":"chemical_species"},"role":"nutrient","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"519971b1-5aef-5ad7-8022-840144855cd0","slug":"metformin","display_name":"Metformin","entity_type_key":"drug"},"role":"drug-exposure","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"08849c17-39b5-5864-ad24-d9f015342b28","slug":"carbon13-cyanocobalamin-tracer","display_name":"Carbon-13-labeled cyanocobalamin tracer","entity_type_key":"small_molecule"},"role":"probe","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"8e2a5a1f-cd49-5f28-8611-325266fb78a6","slug":"calcium","display_name":"Calcium","entity_type_key":"nutrient_element"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"938fee66-3ad1-51e3-ab18-515d6c815d9c","slug":"carbon13-cyanocobalamin-bioavailability","display_name":"Oral carbon-13 cyanocobalamin tracer bioavailability","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"true","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Seven healthy adult completers; three experimental days separated by one-month washouts","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Metformin 850 mg plus calcium 500 mg and carbon-13 cyanocobalamin","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Small acute tracer pilot in healthy adults; cannot establish prevention of chronic deficiency or identify the exact molecular metformin target. Doses describe the experiment, not advice.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"vitamin-b12","display_name":"Vitamin B12 (cobalamins)","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Calcium coadministration reversed the tracer reduction in this pilot.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[muralidharan-2024-calcium] Effect of calcium supplementation on reversing metformin-based inhibition of vitamin B12 bioavailability in healthy adults using a [13C] cyanocobalamin tracer - A pilot study. (2024). https://pubmed.ncbi.nlm.nih.gov/38901951/ DOI: 10.1016/j.clnesp.2024.04.024","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Intestinal absorption assessed from serial venous tracer measurements","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"d9a6bc0d-6627-5aae-96ef-37b7e6e9280d","evidence_kind":"source_excerpt","locator":"Lines 465-476","start_line":465,"end_line":476,"excerpt":"### b12-abs-calcium-tracer-rescue\nAdding calcium 500 mg to metformin 850 mg raised mean tracer bioavailability from 30.8% to 46.4% in seven healthy completers (p=0.003).\nCondition category: normal\nnutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Calcium coadministration reversed the tracer reduction in this pilot.\norganism: Homo sapiens\ntissue_or_cell_type: Intestinal absorption assessed from serial venous tracer measurements\nexperimental_model: Seven healthy adult completers; three experimental days separated by one-month washouts\nlimitations: Small acute tracer pilot in healthy adults; cannot establish prevention of chronic deficiency or identify the exact molecular metformin target. Doses describe the experiment, not advice.\nexposure: Metformin 850 mg plus calcium 500 mg and carbon-13 cyanocobalamin\ncross_nutrient: true\n[muralidharan-2024-calcium] Effect of calcium supplementation on reversing metformin-based inhibition of vitamin B12 bioavailability in healthy adults using a [13C] cyanocobalamin tracer - A pilot study. (2024). https://pubmed.ncbi.nlm.nih.gov/38901951/ DOI: 10.1016/j.clnesp.2024.04.024","model_system":"Seven healthy adult completers; three experimental days separated by one-month washouts","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [muralidharan-2024-calcium] Effect of calcium supplementation on reversing metformin-based inhibition of vitamin B12 bioavailability in healthy adults using a [13C] cyanocobalamin tracer - A pilot study. (2024). https://pubmed.ncbi.nlm.nih.gov/38901951/ DOI: 10.1016/j.clnesp.2024.04.024","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"73145023-2982-5848-aff2-8d8875d6b9c5","stable_key":"import-7fc92b9e-9cbf-556e-8719-6b5244625250","title":"Vitamin B12: 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":"ad5b3a51d36e856aa7fdfd1cc23f690b094689bad87d28e1a621a54675a01c92","revision_id":"118bd616-0c13-549f-bfeb-bc439715b89c","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}