 Although breast milk is the first choice for nutrition of preterm infants 6, 7, it falls short of meeting all of the nutritional needs of VLBW infants unless fortified 8-10. Therefore, standard fortification addition of a fixed amount of a commercial fortifier to breast milk has become a commonly used method in neonatal intensive care units NICUs 11, 12. Standard fortification is performed based on assumptions made about the protein level in breast milk. However, protein levels show inter- and intra-individual variation, and the assumed levels in the milk of the mothers of preterm infants 2.1-2.4 g100 kcal is reduced to 1.5 g100 kcal after the 14th day of lactation 10, 13-17. The protein content of commercial fortifiers ranges from 0.7 to 1.1 g100 mL, and they thus can only increase the amount of protein in breast milk to 3.25 g100 kcal. Therefore, the standard fortification method fails to meet the daily protein need of 3.5-4.5 gkgday of VLBW infants that is recommended by the European Society for Pediatric Gastroenterology Hepatology and Nutrition 18, 19. 