Abstract
Human milk feeding (HMF), through direct breastfeeding (BF) and expressed HM, is the optimal source of infant nutrition, yet practical guidance for inherited metabolic disorders (IMDs) remains limited outside phenylketonuria (PKU). This review summarises strategies, challenges, and clinical considerations for implementing HMF across IMDs requiring dietary modification. A comprehensive search identified studies reporting practical aspects of HMF in disorders of amino acid metabolism, organic acidaemias, urea cycle disorders, fatty acid oxidation disorders, and peripheral galactose epimerase deficiency. Data were synthesised qualitatively. Fifty-one publications describing 1470 infants were included. Successful HMF was reported across all disorders in scope, although feeding strategies varied. In asymptomatic infants, BF on demand was broadly feasible, typically combined with appropriate medical infant formula. In symptomatic infants at diagnosis, BF was generally temporarily interrupted during acute management and reintroduced during a transition phase using controlled volumes of expressed HM and medical infant formula. Re-establishment of BF on demand was possible in many, but not all, infants. Key challenges to BF included maternal anxiety, poor feeding at birth for symptomatic infants and during acute illness, need for complex feeding regimens, frequent hospitalisations in severe IMDs, prematurity, and insufficient HM supply. Successful HMF depended on close disorder-specific metabolic biochemical and growth monitoring with regular adjustment of dietary prescriptions. Maintaining lactation required early, structured support of mothers. HMF is feasible across many IMDs when integrated into individualised, risk-stratified feeding plans. Multidisciplinary support is crucial. Greater standardisation of reporting and wider dissemination of clinical experience are needed to strengthen future recommendations.