Nutrition therapy, first introduced 6 decades ago, remains the primary treatment for phenylalanine hydroxylase (PAH) deficiency.1,2,3 The goals of lifelong nutrition therapy include normal physical growth and neurocognitive development, maintenance of adult health, and normal gestational outcomes in pregnant women with PAH deficiency. Knowledge of metabolism, the pathophysiology of PAH deficiency, and the role of nutrition has led to new and improved treatment options, modified low-protein foods, and medical foods that provide protein equivalents and other nutrients when intact protein food sources must be limited. Table 1 contains definitions of modalities used in the nutrition treatment of aminoacidopathies, including PAH deficiency. Lifelong treatment is recommended because of the negative association between elevated blood phenylalanine (PHE) and neurocognition, yet national nutrition recommendations for PAH deficiency are lacking. The goals of the present evidence- and consensus-based recommendations are to translate current knowledge to patient care, foster more harmonious clinical practices, and promote healthy eating, with the ultimate goal of ensuring better outcomes for individuals with PAH deficiency. This document serves as a companion to the concurrently published American College of Medical Genetics and Genomics (ACMG) guideline for the medical treatment of PAH deficiency.4