Objective: To evaluate dietary protein's effect on fat accretion and weight gain in hospitalized preterm infants.
Methods: Prospective, randomized, double-blind, controlled trial of 36 infants born at <32 weeks, hospitalized in a tertiary neonatal intensive care unit. After achieving full enteral volume, infants were randomized to either an enhanced protein diet (EPD) (protein-energy ratio [PER] 4 g/100 calories) or a standard protein diet (SPD) (PER 3 g/100 calories). Macronutrients were calculated using published values for formula, donor milk bank analysis, or weekly analysis of a 24-hour pooled maternal milk sample. Human milk fortifier and/or liquid protein were used to achieve the target PER until discharge or a maximum of 4 weeks. Body composition was measured weekly using air displacement plethysmography. The principal outcomes, rates of weight gain and fat accretion, were compared between groups in linear mixed models.
Results: Thirty-three infants received approximately 17 days of the study diet. Relative weight gain was 21.6 g · kg · day (95% confidence interval [CI] 19.5-23.8) for the EPD group (n = 16) versus 19.1 g · kg · day (95% CI 17.0-21.2) for the SPD group (n = 17), P = 0.095. Baseline percent fat mass (FM) in the EPD group was 5.15% (95% CI 3.58%-6.72%) compared with 7.29% (95% CI 5.73%-8.84%) in the SPD group, P = 0.0517. Percent FM increased 0.398%/day (95% CI 0.308-0.488) for the EPD group versus 0.284%/day (95% CI 0.190-0.379) for the SPD group (P = 0.0878).
Conclusions: Preterm infants with a lower baseline FM percentage who received an EPD demonstrated a more pronounced catch-up percentage of fat accretion.
Trial registration: ClinicalTrials.gov NCT02353013.