{"id":"772fcc4b-d7f3-528e-b4b9-f6aff3cab8b5","stable_key":"434e1e27-eb90-583a-956b-62472726ffba:cal-meal-nonheme-iron","predicate":"has_reported_effect_on","statement":"Added calcium reduced nonheme-iron absorption in the studied meals.","claim_class":"observational","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"9c2f5f9c-2a47-507c-baa5-1f88ceac393a","mechanism_event_label":"Calcium can reduce iron absorbed from a particular meal.","subject":{"id":"8e2a5a1f-cd49-5f28-8611-325266fb78a6","slug":"calcium","display_name":"Calcium","entity_type_key":"nutrient_element"},"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":"9c2f5f9c-2a47-507c-baa5-1f88ceac393a","stable_key":"434e1e27-eb90-583a-956b-62472726ffba:cal-meal-nonheme-iron-event","event_type":"observed_intervention","label":"Calcium can reduce iron absorbed from a particular meal.","description":"Added calcium reduced nonheme-iron absorption in the studied meals.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"8e2a5a1f-cd49-5f28-8611-325266fb78a6","slug":"calcium","display_name":"Calcium","entity_type_key":"nutrient_element"},"role":"tested_input","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"4429d8ae-d732-5f5e-acc1-2c872e23da62","slug":"nonheme-iron-absorption","display_name":"Nonheme iron absorption","entity_type_key":"cellular_process"},"role":"measured_outcome","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"c2aa7eed-f0d8-5183-b4e3-4503da8c14a5","slug":"calcium-chloride","display_name":"Calcium chloride","entity_type_key":"chemical_species"},"role":"tested_calcium_form","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"59d6d1cd-df32-5b58-b950-3188bc7b95d6","slug":"iron-ii","display_name":"Ferrous iron","entity_type_key":"ion"},"role":"iron_substrate","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"experimental_model","value_text":"Human isotope meal experiments.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Meal processing/phytate and direct effects both occurred; no specific molecular transporter was identified and long-term iron deficiency was not demonstrated.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Calcium research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"calcium","display_name":"Calcium","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Calcium can reduce iron absorbed from a particular meal.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[cal-clin-hallberg1991] Calcium: effect of different amounts on nonheme- and heme-iron absorption in humans (1991). https://pubmed.ncbi.nlm.nih.gov/1984335/ DOI: 10.1093/ajcn/53.1.112","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Human clinical or absorption endpoint","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"90f00b02-f390-5e9a-9b01-e164c7259b12","evidence_kind":"source_excerpt","locator":"Lines 1412-1421","start_line":1412,"end_line":1421,"excerpt":"### cal-meal-nonheme-iron\nAdded calcium reduced nonheme-iron absorption in the studied meals.\nCondition category: normal\nnutrient_topic: Calcium research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Calcium can reduce iron absorbed from a particular meal.\norganism: Homo sapiens\ntissue_or_cell_type: Human clinical or absorption endpoint\nexperimental_model: Human isotope meal experiments.\nlimitations: Meal processing/phytate and direct effects both occurred; no specific molecular transporter was identified and long-term iron deficiency was not demonstrated.\n[cal-clin-hallberg1991] Calcium: effect of different amounts on nonheme- and heme-iron absorption in humans (1991). https://pubmed.ncbi.nlm.nih.gov/1984335/ DOI: 10.1093/ajcn/53.1.112","model_system":"Human isotope meal experiments.","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [cal-clin-hallberg1991] Calcium: effect of different amounts on nonheme- and heme-iron absorption in humans (1991). https://pubmed.ncbi.nlm.nih.gov/1984335/ DOI: 10.1093/ajcn/53.1.112","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"3c083fa0-59c6-50e9-af42-678d0e3c1006","stable_key":"import-434e1e27-eb90-583a-956b-62472726ffba","title":"Calcium: mechanism-first literature curation (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":"965c934d6b147f2b62f8d45ce6d7a87681a600bfe5c46a585b4704889afd3fc1","revision_id":"543ec48b-4f70-5197-9d76-f5a3c443664c","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[{"id":"8b29f1af-9fb7-5aa7-abd2-5fb41eb4ecbb","title":"Acute iron absorption and long-term iron status are different outcomes","kind":"qualification","status":"open","why":"Meal-level absorption inhibition cannot be extrapolated into inevitable iron deficiency. Adaptation is a candidate explanation; these experiments do not establish its molecular basis.","resolution":"Unresolved; needs review.","created_at":"2026-09-17 08:08:54","record_type":"conflict","display_label":"Recorded conflict","record_url":"/conflicts/8b29f1af-9fb7-5aa7-abd2-5fb41eb4ecbb","sides":[{"conflict_id":"8b29f1af-9fb7-5aa7-abd2-5fb41eb4ecbb","ordinal":0,"label":"Calcium can reduce iron absorbed from a particular meal.","revision_id":"543ec48b-4f70-5197-9d76-f5a3c443664c","start_line":1412,"end_line":1421,"quote":"### cal-meal-nonheme-iron\nAdded calcium reduced nonheme-iron absorption in the studied meals.\nCondition category: normal\nnutrient_topic: Calcium research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Calcium can reduce iron absorbed from a particular meal.\norganism: Homo sapiens\ntissue_or_cell_type: Human clinical or absorption endpoint\nexperimental_model: Human isotope meal experiments.\nlimitations: Meal processing/phytate and direct effects both occurred; no specific molecular transporter was identified and long-term iron deficiency was not demonstrated.\n[cal-clin-hallberg1991] Calcium: effect of different amounts on nonheme- and heme-iron absorption in humans (1991). https://pubmed.ncbi.nlm.nih.gov/1984335/ DOI: 10.1093/ajcn/53.1.112","source_key":"import-434e1e27-eb90-583a-956b-62472726ffba","source_title":"Calcium: mechanism-first literature curation (2026-09-17)","claim_ids":["772fcc4b-d7f3-528e-b4b9-f6aff3cab8b5"]},{"conflict_id":"8b29f1af-9fb7-5aa7-abd2-5fb41eb4ecbb","ordinal":1,"label":"No significant worsening of iron markers was found after a year of supplementation in these girls.","revision_id":"543ec48b-4f70-5197-9d76-f5a3c443664c","start_line":1434,"end_line":1444,"quote":"### cal-iron-status-longterm\nOne year of calcium supplementation did not significantly alter measured iron-status markers in adolescent girls.\nCondition category: normal\nnutrient_topic: Calcium research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: No significant worsening of iron markers was found after a year of supplementation in these girls.\norganism: Homo sapiens\ntissue_or_cell_type: Human clinical or absorption endpoint\nexperimental_model: 113 girls, randomized double-blind placebo-controlled trial.\nlimitations: Does not establish absence of effect in iron-deficient people; hemoglobin, ferritin and soluble transferrin receptor are distinct endpoints.\nexposure: 500 mg calcium/day with evening meal for one year; reported marker comparisons were nonsignificant.\n[cal-clin-molgaard2005] Long-term calcium supplementation does not affect the iron status of 12-14-y-old girls (2005). https://pubmed.ncbi.nlm.nih.gov/16002806/ DOI: 10.1093/ajcn.82.1.98","source_key":"import-434e1e27-eb90-583a-956b-62472726ffba","source_title":"Calcium: mechanism-first literature curation (2026-09-17)","claim_ids":["2b926d73-9773-5eb4-916b-5359095dda23"]}]}],"corrections":[],"research":null}