Supplementary Material for: Essential fatty acid supplementation and early inflammation in preterm infants: Secondary analysis of a randomized clinical trial

Introduction: Postnatal inflammation is associated with increased mortality and adverse outcomes in preterm infants. The essential fatty acids arachidonic acid (ARA) and docosahexaenoic acid (DHA) are precursors of lipid mediators with a key role in resolving inflammation. Our aim was to investigate the effect of ARA and DHA supplementation on systemic inflammation in very preterm infants and to identify clinical factors associated with early inflammation. Methods: Secondary analysis of data from a randomized clinical trial (ImNuT study). Infants with gestational age (GA) less than 29 weeks were randomized to receive a daily enteral supplement with ARA 100 mg/kg and DHA 50 mg/kg (ARA:DHA group) or MCT-oil (control group) from the second day of life to 36 weeks postmenstrual age. ARA, DHA and four pro-inflammatory cytokines (IL-1beta, IL-6, IL-8, and TNF-alpha) were analyzed in repeated dried blood samples from birth to day 28 and the area under the curve (AUC) for each variable was calculated. Results: The intention to treat population included 120 infants with mean (SD) GA 26.4 (1.7). The ARA:DHA group had significantly lower IL-6 levels from day 3 to day 28 compared to the control group, mean difference AUC log10 (95% CI) 0.16 (0.03-0.30) pg/mL, p= 0.018. There was no correlation between ARA or DHA blood concentrations and cytokine levels. Having a low gestational age was independently associated with increased levels of all cytokines during the first 4 weeks of life. Conclusions: Enhanced supplementation with ARA and DHA may modulate inflammation in very preterm infants.