Selective changes in gangliosides of human milk during lactation: a molecular indicator for the period of lactation

Abstract

Gangliosides of human milk from women at various periods of lactation were analyzed. G D3, in colostrum. particularly in the early period of lactation, was the major ganglioside, and the molar ratio of G M3 to G D3 was 0.2–0.3 in the milk at 2–6 days postpartum. In contrast, milk from women at 60–390 days postpartum contained G M3 as the major ganglioside and the molar ratio of G M3 to G D3 was more than 3. Milk at 8–40 days postpartum represented an intermediate stage in terms of the ratio of G M3 to G D3. The selective change in the molar ratio of gangliosides was observed as a phenomenon common to all human milk from different individuals at different periods of lactation, indicating that the periods of lactation can be defined on the basis of the ratio. Since glycolipids in human milk are preferentially localized in the milk fat globule membrane, which is derived from the plasma membrane of epithelial cells in the mammary gland, the changes in the ganglioside composition reported in this communication may reflect a qualitative change of the cells in the mammary gland.