Maternal sodium intake does not affect postprandial sodium concentrations in human milk.

Sodium concentration in human milk is known to vary diurnally and throughout lactation. To investigate potential postprandial variation, eight exclusively breast-feeding mothers of infants 10-19 wk of age were visited on two different days after a 3-h fast. On one day, they were fed a low sodium lunch (130 mg), and on the other, the same lunch with a high sodium content (2175 mg). Milk samples were collected before each lunch and breasts were emptied with an electric pump. After lunch, samples were collected from each breast every 15 min for 2 h. No significant postprandial variation was found in mean sodium or potassium concentrations, nor were significant differences found in sodium or potassium values after the high sodium or the low sodium lunch. We conclude that there is no significant influence of maternal sodium intake on postprandial milk sodium or potassium concentrations.