Plant stanols have been shown to reduce serum levels of low-density lipoprotein (LDL) cholesterol, and they are an attractive adjunct in dietary therapy for elevated LDL cholesterol. This investigation addressed 3 questions through metabolic studies in human subjects: (1) whether plant stanol esters given at higher doses than the 2-g/day dose recommended by the National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III) will provide additional LDL-lowering efficacy (study 1); (2) whether substantial reduction in LDL cholesterol can be obtained in postmenopausal women with hypercholesterolemia by addition of plant stanol esters to the diet (study 2); and (3) whether ATP III goals can be obtained by adding plant stanol esters to an LDL-lowering regimen in high-risk patients who retain LDL cholesterol levels in the above-optimal range (ie, 2.6 to 3.3 mmol/L [100 to 129 mg/dL]), despite ongoing statin therapy (study 3). Study 1 showed that maximal LDL lowering with plant stanols in the form of esters can be achieved at a dose of 2 g/day. Higher doses do not provide additional efficacy. Study 2 demonstrated that stanol esters can reduce LDL cholesterol levels in postmenopausal women by about 13%, which makes use of stanol esters attractive as a component of nondrug therapy in these women who generally are at relatively low risk for coronary heart disease. Finally, study 3 found that plant stanols provide additional lowering of LDL cholesterol when added to ongoing statin therapy. This makes plant stanols an attractive dietary component to help to achieve the goals of LDL-lowering therapy in patients requiring an LDL-lowering drug.