Sequential study on glutathione peroxidase and selenium contents of human milk.
Breast milk samples collected sequentially from five lactating women were analysed for selenium and Se-dependent glutathione peroxidase (GSH-Px), which is the only active form of Se known in man. Both GSH-Px and Se contents of breast milk decreased with increasing time of lactation and reached a plateau at a month post-partum. This sequential change was not due to the Se intake of the mother as reflected in urinary Se content. GSH-Px and Se contents of mature milk were strictly regulated irrespective of the Se intake of the mother. There was a significant positive correlation between GSH-Px and Se contents of breast milk. Mean GSH-Px and Se contents and the proportion of GSH-Px-bound Se content of the total Se content in mature milk were 38.8 U ml-1, 22.5 ng ml-1 and 23.4%, respectively. Preservation of mature milk at -20 degrees C decreased linearly its GSH-Px activity with increasing time at a rate of 5.8 U ml-1 day-1.
D000328:Adult; D000818:Animals; D005260:Female; D005979:Glutathione Peroxidase / Q000032:analysis* / Q000652:urine; D006801:Humans; D008895:Milk, Human / Q000032:analysis*; D012643:Selenium / Q000032:analysis* / Q000652:urine; D013997:Time Factors
D005979:Glutathione Peroxidase; D012643:Selenium