Human Milk Fortifiers for Preterm Infants: Do We Offer the Best Amino Acid Mix?

Area of Science:

• Neonatal Nutrition
• Pediatric Gastroenterology
• Biochemistry

Background:

• Preterm and small-for-gestational age infants require specialized enteral nutrition.
• Human milk fortifier (HMF) supplementation to human milk (HM) is standard practice.
• Preterm infants have significantly higher protein and amino acid (AA) requirements than term infants due to rapid lean body mass accretion.

Purpose of the Study:

• To systematically assess the amino acid (AA) profile of human milk fortifiers (HMFs).
• To calculate advisable AA intakes for preterm infants based on fetal growth data.
• To evaluate the adequacy of current HMF formulations for preterm infant nutrition.

Main Methods:

• Calculated advisable AA intakes for preterm infants (400-2,500 g) using fetal growth increments.
• Incorporated corrections for AA absorption, losses, oxidation, and HM variability.
• Assessed AA intakes from standard HM protein fortification levels (3.5-4 g/kg BW/day).

Main Results:

• Extremely low birth weight (ELBW) and very low birth weight (VLBW) infants have substantially higher AA requirements than low birth weight (LBW) infants.
• Current HMFs, at recommended protein intakes, provide insufficient levels of several indispensable and conditionally indispensable AAs for ELBW and VLBW infants.
• Some AAs, like isoleucine and leucine, are provided in excess in current HMFs at standard fortification levels.

Conclusions:

• The AA composition of current HMFs requires reconsideration to meet the specific needs of preterm infants, especially ELBW infants.
• Targeted AA-based HMFs or spiking existing HMFs with limiting AAs are potential strategies to improve nutritional adequacy.
• Optimizing AA profiles in HMFs is essential for supporting the rapid growth and development of preterm infants.