PURPOSE OF REVIEW: This review aims to evaluate the latest available evidence on the differences between human milk proteins versus infant formula proteins and its effects on growth and development in preterm infants. RECENT FINDINGS: High protein intake supports initial growth in preterm infants, although the long-term benefits remain unclear. Human milk requires adequate fortification to meet nutritional needs of preterm born infants. Formula feeding, with its higher protein content, may accelerate early weight gain but also increases the risk of necrotizing enterocolitis. Current evidence showed no significant advantages of human milk-derived fortifiers over bovine milk-derived fortifiers. Furthermore, studies published during the review period do not provide new evidence that alters the existing understanding of differences in neurodevelopmental outcomes between infants fed human milk and those fed formula. SUMMARY: Both fortified human milk and preterm formula support growth in preterm infants, but human milk offers additional protective benefits, such as reducing the risk of necrotizing enterocolitis, making it the preferred option. Balancing immediate growth needs with potential long-term developmental outcomes remains crucial, highlighting the need for further research to determine the optimal protein intake for preterm infants.