Bibian van der Voorn

95 STABILITY OF CORTISOL AND CORTISONE IN HUMAN BREAST MILK INTRODUCTION When own mother’s milk is not available, human donor milk is advised as the second-best nutrition for preterm infants, because of its supportive effects on infant development 1 . Pasteurization of donor milk is imperative, minimizing transmission of pathogens. Currently, the most commonly used process by human milk banks for pasteurization of donor milk is Holder pasteurization, which includes 30 minutes of heating at 62.5°C followed by fast cooling 2 . Although this heating process can affect the milk quality by the reduction of nutritional and bioactive components, and inactivation of beneficial microbiota 1,3 , it is thought to be the best available compromise between safety and quality 2 . A variety of non-nutritive bioactive components have been detected in human milk, including hypothalamic, pituitary, thyroid, parathyroid, adrenal, gastrointestinal and growth hormones 4 . We found that breast-milk glucocorticoids were highly correlated to maternal HPA axis activity 6 . Moreover, animal studies have shown that milk glucocorticoids are readily absorbed by the neonatal intestine, exerting a local, as well as a systemic anti-inflammatory effect on the gastrointestinal tract of the newborn 4,7 . In addition, observational studies suggested that milk cortisol influences infant neurodevelopment 8,9 . In infants born preterm the HPA axis is not yet fully maturated and is relatively insufficient during the first weeks of life, reflected by low cortisol levels for the degree of illness aswell as increased risks of hypotensionandhypoglycemia 10 . Glucocorticoids in breast milk could provide resilience against potentially life-threatening illnesses. The bioavailability of some milk hormones has been shown to be altered by Holder pasteurization and reduced concentrations of insulin-like-growth-factors, growth hormone, leptin, adiponectin and insulin have been described 1 . There is little evidence with regard to the effects of Holder pasteurization on glucocorticoid levels in human milk 5 . The objective of this study was therefore to determine whether Holder pasteurization affects milk cortisol and cortisone concentrations, thereby influencing the bioavailability of milk glucocorticoids in human donor milk.