Impact of homogenization of pasteurized human milk on the kinetics of gastric digestion in the preterm infant

Ensuring adequate growth of preterm neonates remains a challenge. It has been suggested that homogenization of Holder-pasteurized human milk (PHM) could improve fat absorption and weight gain. The objective of the present work was to determine the impact of PHM homogenization on gastric digestion in preterm infants. In a randomized controlled trial (NCT02112331), eight hospitalized tube-fed preterm infants were their own control to compare the gastric digestion of PHM and of homogenized PHM (PHHM). PHM was obtained from donors and, for half of it, was homogenized by ultrasonication. Over a six-day sequence, gastric aspirates were collected twice a day, before and 35, 60 or 90 min after the start of PHM or PHHM ingestion. The impact of homogenization on PHM digestive kinetics and disintegration was tested using a general linear mixed model. Results were expressed as means ± SD. Homogenization leaded to a six-fold increase of the specific surface (P<0.01) of lipid droplets. The nature of aggregates formed during digestion were different between PHM and PHHM, but the lipid fraction kept its initial structure all over the gastric digestion (native globules in PHM vs. neoformed droplets in PHHM). Homogenization increased the gastric lipolysis level (P<0.01), particularly at 35 and 60 min (22 and 24% higher for PHHM, respectively). It enhanced the proteolysis of serum albumin (P<0.05) and reduced the meal emptying rate (P<0.001, gastric half-time estimated at 30 min for PHM and 38 min for PHHM). The postprandial gastric pH was not affected and was at 4.7 ± 0.9 at 90 min after the feeding start. To conclude, homogenization of PHM increased the gastric lipolysis level. This could be a potential strategy to improve fat absorption, and thus growth and development in infants fed with PHM, but its gastrointestinal tolerance needs to be investigated further.