Supplementation with long-chain polyunsaturated fatty acids to extremely preterm infants associates with development of the intestinal microbiota

BACKGROUND: Supplementation with arachidonic acid (AA) and docosahexaenoic acid (DHA) to extremely preterm infants reduces the risk of severe retinopathy of prematurity (ROP). The main aim of this study was to explore the involvement of AA:DHA supplementation in the developing gut microbiome, and its possible contribution to the ROP-protective effect. Secondly, additional covariates for microbiome maturation were evaluated. METHODS: Longitudinal gut microbiome profiles and bacterial gene pathways were characterised using shot-gun metagenomics in 75 extremely preterm infants who participated in a randomized clinical trial on AA:DHA supplementation. Serum protein levels quantified using proximity extension assays were merged with the microbiome data. RESULTS: AA:DHA supplementation was linked to an increase in relative abundance of Citrobacter koseri and associated with changes in proteins and metabolic pathways. Occurrence of severe ROP was associated with microbiome alpha diversity (Shannon and Evenness) and beta diversity (Bray-Curtis). Additionally, study centre and gestational age at birth impacted the microbiome composition. CONCLUSION: We conclude that AA:DHA supplementation impacts the microbiome. However, the current study could not determine the causality between the supplementation, microbiome and ROP-decrease. Nonetheless, these findings highlight the complex interplay between external interventions, including nutritional supplements, and the gut microbiome development in extremely preterm infants. IMPACT: Longitudinal gut microbiome profiles, bacterial gene pathways and serum protein expressions were determined using shotgun metagenomics and proximity extension assays in 75 extremely preterm infants included in a multicentre randomized clinical trial investigating enteral fatty acid supplementation. Dynamic shifts in microbiome and pathway composition were seen from birth to 34 weeks gestational age. Arachidonic acid (AA) and docosahexaenoic acid (DHA) supplementation was linked to an increase in relative abundance of Citrobacter koseri and associated with changes in proteins and metabolic pathways. However, the causality between the supplementation, microbiome, and ROP-decrease could not be determined.