The present invention relates to enteral formulations for preterm infants (e.g., preterm formulas and human milk fortifiers) containing optimised intake levels of phenylalanine for the preterm infants. It particularly relates to a preterm formulation comprising a proteinaceous composition, wherein the preterm formulation (a) comprises 2.0-2.29 g phenylalanine per 100 g protein； (b) comprises 64.00-82.29 mg phenylalanine per 100 kcal； and/or (c) provides, or is formulated to provide phenylalanine in an amount of 80-96 mg/kg body weight per day.
