Study	Reason for exclusion
Bering 2018	Not an RCT
Dasopoulou 2015	RCT of prebiotics
Dilli 2013	Participants were not very preterm or VLBW
Panigrahi 2008	Participants were not very preterm or VLBW
Serce Pehlevan 2020	RCT ‐ the intervention group also received lactoferrin (co‐intervention)
Underwood 2014	RCT comparing supplementation of formula with either prebiotic oligosaccharides or (quote:) “a pooled concentrated donor human milk product”
Vakiliamini 2020	Most participants were not very preterm or VLBW (subgroup data not available)

RCT: randomized controlled trial; VLBW: very low birth weight