Twenty-one women, lifelong residents of Xichang County, Sichuan Province, China, an area of very low soil selenium (Se), received tablets containing either 100 μg Se daily as Se-enriched yeast (+Se) or no additional Se (-Se), throughout the last trimester of pregnancy and the first three months of lactation. Diet was analyzed using diet recalls and proximate analysis of mixed diet samples. Milk and plasma samples were analyzed for Se content, glutathione peroxidase activity, and fatty acid profile and plasma alone was analyzed for vitamin E content and lipid peroxidation. At parturition and three months after delivery, milk and plasma Se levels and plasma GPx activities were significantly higher in the +Se women than the -Se women. Milk GPx activity did not change significantly with supplementation. Plasma vitamin E was not different between the treatment groups at either time. Plasma lipid peroxidation levels (TBARS) were significantly higher in the supplemented women at both time points. Fatty acid profiles at delivery and three months after delivery were similar in both plasma and milk between the two groups. The data suggest that this level and length of supplementation, when given to pregnant women of very low Se status, are not adequate to influence the fatty acids in milk. / Graduation date: 2000

Numerous dietary factors have been shown to influence the fatty acid profiles (FAP) in breast milk from lactating women. However, few studies have evaluated the effect of trace minerals on milk FAP. Consequently, the purpose of this study was to determine the effect of selenium status on the FAP in breast milk. Subjects were lactating women from three different regions in China; Xichang (n=21), an area where selenium intakes are among the lowest in the world, Beijing (n=20), where there are adequate selenium intakes, and Enshi (n=19), where selenium intakes are among the highest in the world. Plasma and milk samples were obtained from women at birth of their baby and within 10 months postpartum and analyzed for selenium content, glutathione peroxidase (Gpx) activity and FAP. Plasma and breast milk selenium levels were significantly lower in the Xichang women and significantly higher in the Enshi women when compared to Beijing women. Despite the fact that the highest level of plasma selenium was measured in the samples from Enshi, the Gpx activity was greatest in the samples from Beijing; there was no effect of time of sampling on these samples. In breast milk, on the other hand, all the samples obtained at birth had similar activity of Gpx. The samples taken later, however, followed the same trend as plasma with the samples obtained from the women in Beijing having the highest activity. FAP indicated a significant difference in the amount of unsaturated fatty acids in both the plasma and milk for the Beijing women, when compared to the women from Xichang and Enshi. In particular, there were higher levels of linoleic acid, 18:2(n-6), in the plasma and milk of the women whose selenium intake was adequate. / Graduation date: 1997