Human breastmilk storage and the glutathione content.

Human breastmilk storage for use later in infant feeding is on the increase as a result of the economic activities of nursing mothers. This study investigated glutathione (GSH) status of stored human breastmilk due to its major antioxidant role and as a cofactor for enzymes in detoxification of carcinogens. In newborns, human breastmilk becomes an important source of dietary GSH since their GSH synthetic capacity may not be well developed. The results showed that the total GSH content of human breastmilk obtained from apparently healthy lactating mothers was 192.2 +/- 148.3 mumol/l (mean +/- SD). Early breastmilk (fed to infants up to 4 weeks old; GSH content of 252.5 +/- 173.9 mumol/l) was significantly higher (p < 0.05) when compared with their mature counterpart (milk from mothers with infants older than 1 month of age; GSH content 163.9 +/- 128.0 mumol/l). Substantial loss of GSH occurred when breastmilk was kept at either -20 degrees C, 4 degrees C or at room temperature for 2 h. When compared with fresh unstored breastmilk, the extent of the loss was 80.6, 79.1 and 73.0 per cent respectively. It is suggested that feeding infants on stored human milk could weaken the antioxidant and toxin refractory capacity of those in early childhood.