Effect of hydrolyzed formulas on gastrointestinal tolerance in preterm infants: a systematic review and meta-analysis

Hydrolyzed formulas (HFs) have been increasingly used in early enteral feeding in preterm infants. The current study aimed to compare the effect of HFs with standard preterm formula (SPF) on gastrointestinal tolerance in preterm infants by systematically reviewing the randomized controlled trials (RCTs) related. Relevant studies published until August 2021 were searched in English and Chinese databases, including PubMed, Embase, Cochrane Library, CNKI, WanFang Data, and VIP. Three outcomes, including the incidence of feed intolerance (FI), necrotizing enterocolitis (NEC), and the time to full enteral feeding, were chosen to evaluate the effect on gastrointestinal tolerance comprehensively. Ten eligible studies with 886 participants were included in the final analysis. Infants who received HFs showed a lower risk of FI (RR = 0.61, 95% CI = 0.42–0.90; p < .05) and shorter time to full enteral feeding (MD = -0.56, 95% CI = −1.03 to −0.10; p < .05) compared with those fed with SPF. There was no significant difference in risk of NEC (RR = 0.48, 95%CI = 0.21 − 1.08; p > .05) between the two groups. The results showed that HFs may have benefits in improving gastrointestinal tolerance in preterm infants, including reducing the risk of FI and shortening the time to full enteral feeding.