To investigate octacosanol (OC) metabolism in humans and its influence on cholesterol metabolism, two studies were conducted. In the first study ten healthy women received daily 30 mg OC for a period of 4 weeks. Blood and feces samples were collected at baseline and after the intervention. Serum concentrations of total cholesterol, LDL cholesterol, and HDL cholesterol were not altered following OC administration. Concentrations of excreted cholesterol end products decreased with the intervention (neutral sterols: 24.6 +/- 9.7 mg/g vs. 20.3 +/- 7.5 mg/g dry matter, P < 0.05; bile acids: 6.47 +/- 3.89 mg/g vs. 4.03 +/- 2.26 mg/g dry matter, P < 0.05). OC was not detected in serum samples, but the fecal OC concentration increased after the intervention period (11 +/- 7 microg/g vs. 817 +/- 179 microg/g dry matter, P < 0.05). In the second kinetic study on three participants, OC was identified in serums after oral application of 50 mg OC within 8 h. The decrease in the concentration of fecal cholesterol end products may underline a systemic effect of OC on cholesterol metabolism, even though the serum cholesterol levels were not influenced.