Recent findings have raised concern about possible associations of high selenium exposure with diabetes and hyperlipidemia in the US, a population with high selenium status. In the UK, a population with lower selenium status, there is little data on the association of selenium status with cardio-metabolic risk factors in the general population. We examined the association of plasma selenium concentration with blood lipids in a nationally representative sample of British adults. A cross-sectional study was conducted among 1042 white participants (aged 19-64 y) in the 2000-2001 UK National Diet and Nutrition Survey. Plasma selenium was measured by inductively coupled-plasma mass spectrometry. Total and HDL cholesterol were measured in nonfasting plasma samples. Mean plasma selenium concentration was 1.10 +/- 0.19 micromol/L. The multivariate adjusted differences between the highest (> or =1.20 micromol/L) and lowest (<0.98 micromol/L) quartiles of plasma selenium were 0.39 (95% CI 0.18, 0.60) mmol/L for total cholesterol, 0.38 (0.17, 0.59) for non-HDL cholesterol, and 0.01 (-0.05, 0.07) for HDL cholesterol. Higher plasma selenium (i.e., > or =1.20 micromol/L) was associated with increased total and non-HDL cholesterol levels but not with HDL in the UK adult population. These findings raise additional concern about potential adverse cardio-metabolic effects of high selenium status. Randomized and mechanistic evidence is necessary to assess causality and to evaluate the impact of this association on cardiovascular risk.