Objective:The present study was designed to examine for the first time, side-by-side, the effects of plant sterol and stanol consumption on lipid metabolism and markers of antioxidant status, oxidative stress, endothelial dysfunction and low-grade inflammation in subjects on stable statin–treatment.Design:Double-blind, randomized, placebo-controlled, intervention trial.Setting:University.Subjects:Forty-five patients on current statin treatment were recruited via newspaper advertisements. Data of 41 patients were used in statistical analysis.Intervention:Subjects consumed margarine with no added plant sterols or stanols for 4 weeks and were then divided into three groups of 15 subjects. For the next 16 weeks, one group continued with the control margarine and the other two groups with either a plant sterol- or stanol (2.5 g/day)-enriched margarine. Blood was sampled at the end of the run-in and intervention periods.Results:Plant sterol and stanol consumption significantly (P=0.026) reduced low-density lipoprotein (LDL) cholesterol by 0.34 mmol/l (95% confidence interval (CI), −0.67 to −0.04 mmol/l). No effects were shown on enzymatic and non-enzymatic antioxidants and markers of oxidative modification of lipids and DNA. In addition, no effect was found on soluble adhesion molecules, C-reactive protein and monocyte chemotactic protein-1 concentrations.Conclusions:We conclude that 16 weeks of plant sterol or stanol consumption did not affect markers of antioxidant status, oxidative stress, endothelial dysfunction and low-grade inflammation in patients on stable statin treatment, despite a significant reduction of LDL cholesterol.European Journal of Clinical Nutrition (2008) 62, 263–273; doi:10.1038/sj.ejcn.1602733; published online 9 May 2007 [ABSTRACT FROM AUTHOR]