Water–soluble choline compounds in human milk : their variation and impact of storage and diet.

Choline is an essential nutrient with potentially important roles for infant neurodevelopment. During infancy, choline is usually provided by milk, where is present mostly as water-soluble cholines (WSC). However, published data suggest wide variability in the WSC content with unknown cause, but maternal diet has been suggested as an explanation. It is also unclear if variability results from methodological approach or stability in expressed milk. The objective was to determine the milk WSC content and composition, to determine if variability is present and results from storage, or from expressing WSC/ml, as well as to determine WSC variability within and across women and the potential role of maternal diet. Two studies were conducted: 1) Milk expression and storage on WSC (n=6). Complete milk expressions were analyzed immediately and after different storage conditions. 2) Milk WSC intra and inter-individual variability within one day (n=20), with collection of dietary data. WSC was analyzed using LC-MS/MS and kilocalorie content with a Human Milk Analyzer. ANOVA was used to determine changes in milk WSC following different storage. Correlation analysis was used to explore associations between WSC/ml or kcal, and between maternal diet and milk WSC. Concentration of milk WSC remained similar over short term storage, and only changed when milk was stored for 6 months at -80 °C. Glycerophosphocholine was the most stable WSC;, milk phosphocholine decreased 30% and free choline increased 53 % after 4 hours of storage at room temperature. WSC content and distribution of free choline, phosphocholine and glycerophosphocholine showed wide inter-individual variability, with some women showing high variability at different times in one day. Maternal choline intake was not related to the concentration of milk water-soluble cholines. Only 20% of participants consumed the Adequate Intake=550 mg/d, with eggs as the major food source of choline in the maternal diet. In summary, individual WSC compounds are not stable in expressed milk. The milk WSC content and composition is highly variable across and within women and sampling from one point might not represent infants’ intake. This is the first study addressing the storage and maternal diet as causes for the milk WSC variability.Land and Food Systems, Faculty ofGraduat