This is a double-blind, randomized placebo-controlled pilot study to investigate the efficacy of enteral glutamine (GLN) supplementation in 36 infants, ≤ 12 months of age with parenteral nutrition (PN)-dependent short bowel syndrome (SBS) due to massive small bowel resection for NEC and/or atresia on improving weaning of PN and preventing infections. The investigators intend to evaluate the effect of enteral feeding and GLN supplementation on the gut bacteria. The investigators will also recruit 12 age-matched controls to evaluate the normal gut bacteria.