Phytosterols and Oxyphytosterol Concentrations

Plant sterols and stanols (also called phytosterols and phytostanols) are structurally related to cholesterol, but absorbed to a much lesser extent. Due to this structural similarity, plant sterols and stanols inhibit intestinal cholesterol absorption and lower serum LDL cholesterol concentrations by about 10% at daily intakes of 2.5 g. Plant sterol- and stanol-enriched food products are therefore widely available on the market to lower the risk for coronary heart disease. Plant sterols can undergo oxidation, which results in the formation of oxyphytosterols. Animal studies have now suggested that oxyphytosterols are atherogenic. Although oxyphytosterols have been identified in human serum samples, the effect of an increased intake of plant sterols on serum oxyphytosterol concentrations in humans is not known. On the other hand, plant stanols cannot be oxidized and lower not only cholesterol absorption, but also plant sterol absorption. The major objective of the present study is to examine the effects of dietary plant sterols and stanols on fasting serum concentrations of oxyphytosterols. The minor objective is to investigate the effects of these products on postprandial serum oxyphytosterol concentrations.