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not a replacement recommendation for established PKU management.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"L-Phenylalanine collection; species, compartment, exposure, co-substrates and manipulation remain explicit.","comparator":null,"unit":null,"notes":"","entity":{"slug":"l-phenylalanine","display_name":"L-Phenylalanine","entity_type_key":"small_molecule"}},{"dimension":"plain_language","value_text":"A mixture can change outcomes, but the existing diet affects its added value.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"The effects of large neutral amino acid supplements in PKU: an MRS and neuropsychological study. · 2007 · https://pubmed.ncbi.nlm.nih.gov/17368065/ · DOI 10.1016/j.ymgme.2007.02.002","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"d2144473-af34-50c7-b7f6-1901d9588ec1","evidence_kind":"source_excerpt","locator":"Lines 206-212","start_line":206,"end_line":212,"excerpt":"## l-phenylalanine-lnaa-clinical-boundary\nA mixture can change outcomes, but the existing diet affects its added value.\nIn a 16-person PKU crossover study, LNAA supplementation produced limited executive-function benefits and lowered plasma phenylalanine mainly when participants were not taking their usual medical product.\nModel: Four two-week crossover phases involving LNAA/placebo with or without medical product.\nLimitations: Small, short study; not a replacement recommendation for established PKU management.\nEvidence access: Primary abstract\nThe effects of large neutral amino acid supplements in PKU: an MRS and neuropsychological study. · 2007 · https://pubmed.ncbi.nlm.nih.gov/17368065/ · DOI 10.1016/j.ymgme.2007.02.002","model_system":"Four two-week crossover phases involving LNAA/placebo with or without medical product.","directness":"reported_statement","verification_status":"source_derived_draft","notes":"Original curation paraphrase; evidence access and experimental limitations specified.","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"54de7c56-1e60-5d7b-8ef9-852c58ae92ba","stable_key":"import-56f1d914-e7da-595a-af69-c217b2b47407","title":"L-Phenylalanine: transport, protein synthesis, cofactor recycling and cross-nutrient mechanisms (2026-09-19)","document_type":"imported_text","citation_label":"AI-assisted research curation; primary references, access levels and experimental limitations individually identified. 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