Phytosterols, a double-edged weapon?

Phytosterols are plant sterols structurally similar to cholesterol. The most common phytosterols are B-sitosterol, campesterol and stigmasterol. They are present in many foods but mainly in nuts and vegetable oils. They compete with cholesterol absorption decreasing the cardiovascular risk. Recent studies have associated the intake of 0.63-3g/day of phytosterols with lowering serum cholesterol and LDL-cholesterol levels. The same decrease has been observed in apolipoprotein B. These results suggest that dietary phytosterols are useful for protection against cardiovascular disease. Because of this they have been incorporated in relatively high quantities into spreads and margarines. However, negative effects have also been reported. Among them, a significant decrease in the absorption of several lypophilic antioxidant compounds such as carotenoids and tocopherols, which may counterbalance the protective cardiovascular effect of phytosterols. In this paper the results of several selected studies relating phytosterol consumption and plasma levels of lipids, lipoproteins and antioxidants are reviewed. More studies are needed to establish if it is necessary to supplement with such antioxidant compounds the diet of people consuming phytosterols for therapeutical purposes.