Selenium and zinc status are suboptimal in a sample of older New Zealand women in a community-based study

Abstract

The importance of selenium and zinc in the immune functioning of the aged is widely recognized. Seniors in New Zealand are at particularly high risk of low selenium status because of the low selenium soil environment. The zinc status of the New Zealand elderly has never been assessed. In this cross-sectional study, the biochemical selenium, zinc and lipid levels, physical functional capacity and dietary intakes of 103 randomly selected free-living New Zealand women (mean age±SD, 75±3 y) were assessed. Among nonusers of selenium supplements (n=80), 80% [95% confidence interval (Cl): 70; 88%] had plasma selenium levels (0.85±0.23 μmol/L) below 1.00 /μmol/L [∼10% below mean plasma selenium necessary for full expression of glutathione peroxidase (GPx) activity in New Zealand subjects]. Plasma selenium was strongly correlated with GPx:r=0.56; P<0.0001. For nonusers of zinc supplements (n=88), serum zinc concentrations were 12.4±1.4 μmol/L, with 12% (95% Cl: 6; 21%) having levels below the cut-off value (10.7 μmol/L). Estimated mean daily selenium and zinc intakes were 34±10 μg and 8.7±2.0 mg, respectively. Subjects in the highest tertile of a functional capacity index had higher biochemical zinc and selenium values than those in the lowest tertile (P<0.05). The correlation between plasma selenium and GPx indicates that selenium intake in these women is still insufficient for full expression of GPx activity. Lower serum zinc levels also appear to be prevalent. Because a suboptimal trace element status may be more common among those with a poor physical functioning, promotion of the consumption of nutrient dense foods or supplements to improve selenium and zinc status of elderly women in New Zealand may be beneficial.