A product for preventing preterm neonatal necrotizing enterocolitis gastro-intestinal injury comprising Lactobacillus salivarius strain ATCC 202196, Lactobacillus plantarum strain ATCC 202195, or combinations thereof in ml doses having about 10.sup.8 to 10.sup.11 microorganisms per ml provided in lyophilized form, reconstituted in a vehicle or in coated capsules in the form of acid-resistant slow release microcapsules for naso-gastric feeding to preterm infants before tissue injury for preventing preterm neonatal neonatal necrotizing enterocolitis gastro-intestinal injury.