ABSTRACT
Plant sterols, which are structurally related to cholesterol, have long been known to reduce serum total and low-density lipoprotein (LDL) cholesterol levels when consumed in the diet by lowering the intestinal absorption of dietary and biliary cholesterol (1-4). Plant sterols interfere with cholesterol absorption by decreasing the micellar solubility of cholesterol. Plant sterols are not synthesized by animals or humans but are obtained in the diet primarily from vegetable oils, margarines, and other vegetable oil-based food products. The majority of vegetable oils contain 0.1-0.5g total plant sterols per 100g oil, while some oils such as canola and corn may contain up to 1% (w/w). The major plant sterols in the diet are the unsaturated plant sterols, i.e., β-sitosterol, campesterol, and stigmasterol. Saturated plant sterols (i.e., stanols), such as sitostanol and campestanol, are present in vegetable oils only in trace amounts. Individuals consuming typical Western diets take in 160-360mg/day unsaturated plant sterols and 20-50mg/day stanols (5). At these levels of consumption, plant sterols and stanols have little effect on cholesterol absorption. However, it has been recognized over the last four decades that very large intakes (ranging from 0.8 to 4g/day) can interfere with intestinal absorption of cholesterol and significantly reduce (10-15%) serum cholesterol levels (1-4). Increasing daily intakes above 4g/day is not expected to lead to any further decreases in serum total or LDL cholesterol levels.
