Longitudinal study on the dietary selenium intake of exclusively breast-fed infants and their mothers in Finland.

The dietary selenium intakes of a group of 13 lactating women living in the Helsinki metropolitan area and those of their 10 exclusively breast-fed infants were studied twice during the course of lactation. The first survey period of the women ranged from 6 to 8 weeks post-partum and the second from 17 to 22 weeks post-partum. The selenium intakes of the infants were determined at 1 and 3 months post-partum. In addition, the concentrations of selenium in the breast milk of four of the mothers were determined 6 months post-partum. Milk samples were collected by a method eliminating errors due to diurnal variations and variations during a single feeding. The validity of the analytical method employed was confirmed by means of an interlaboratory collaboration. The level of selenium concentration in the breast milk fell significantly (P less than 0.0005) from 10.7 +/- 1.6 micrograms/l at 1 month of lactation to 5.8 +/- 1.2 micrograms/l at 3 months of lactation, but remained at that level for up to 6 months of lactation (5.6 +/- 0.4 micrograms/l). The total dietary selenium intake of the infants fell significantly (P less than 0.0005) from 8.0 +/- 1.8 micrograms/d to 4.7 +/- 1.1 micrograms/d at 1 and 3 months post-partum, respectively. The mean maternal dietary selenium intake was 36 +/- 13 micrograms/d during the first survey period and 30 +/- 12 micrograms/d during the second survey period.(ABSTRACT TRUNCATED AT 250 WORDS)