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liver rates cannot define a universal intake ceiling.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Folate and folic acid research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"folate","display_name":"Folate (vitamin B9)","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Folic acid needs a reduction step before it becomes usable folate.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[bailey2009] The extremely slow and variable activity of dihydrofolate reductase in human liver and its implications for high folic acid intake (2009). https://pubmed.ncbi.nlm.nih.gov/19706381/ DOI: 10.1073/pnas.0902072106","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Liver enzyme preparations","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"9d7d5ba6-c4a3-5179-9534-31f445e4e3d5","evidence_kind":"source_excerpt","locator":"Lines 351-361","start_line":351,"end_line":361,"excerpt":"### folate-dhfr-folic-acid-first-reduction\nDHFR reduces folic acid to dihydrofolate before further reduction to tetrahydrofolate.\nCondition category: normal\nnutrient_topic: Folate and folic acid research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Folic acid needs a reduction step before it becomes usable folate.\norganism: Homo sapiens\ntissue_or_cell_type: Liver enzyme preparations\nexperimental_model: Fresh human liver extracts from six donors and rat comparison\nlimitations: Reaction identity; liver rates cannot define a universal intake ceiling.\nexposure: Folic acid substrate with NADPH\n[bailey2009] The extremely slow and variable activity of dihydrofolate reductase in human liver and its implications for high folic acid intake (2009). https://pubmed.ncbi.nlm.nih.gov/19706381/ DOI: 10.1073/pnas.0902072106","model_system":"Fresh human liver extracts from six donors and rat comparison","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [bailey2009] The extremely slow and variable activity of dihydrofolate reductase in human liver and its implications for high folic acid intake (2009). https://pubmed.ncbi.nlm.nih.gov/19706381/ DOI: 10.1073/pnas.0902072106","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"f4ce1a62-9582-5f7a-84f5-a23d0e1bfc68","stable_key":"import-ec174d5a-4903-5745-8646-df0e9d4265e8","title":"Folate and folic acid: 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":"e564d43989ece1006c95cd0748e9af6fe369074599a2eebba0a99ebff864b0dd","revision_id":"76674a33-b2a1-5e41-b71b-44399038ff7c","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}