Phytosterols in human health
INTRODUCTION Plant sterols resemble cholesterol structurally in that they all have a steroid nucleus 3-/3-hydroxyl group, and double bond between carbon atoms 5 and 6. Bean (1) has described 44 sterols present in plants. The major ones resemble cholesterol but have substitutions and/or unsaturation in the side chain. The principal plant sterols are ^-sitosterol (24-a-ethylcholesterol), campesterol (24-a-methylcholesterol), and stigmasterol (A22, 24-a-ethylcholesterol). Itoh (2) and Weihrauch and Gardner (3) summarized the sterol composition of a number of foods of plant origin, ^-sitosterol makes up 45-95% of the total sterol of edible plant oils. Campesterol comprises up to 30% of the total sterols of seed oils, and stigmasterol may account for up to 25% of the sterols of some seed oils. Another phytosterol, ergosterol (A7'22, 24-a-methylcholesterol) is the principal sterol (90100%) of yeast and is present in significant amounts in corn, cotton seed, peanut, and linseed oils. Pine oil also yields a mixture of phytosterols, mainly /^-sitosterol, which are called tall oil sterols (Tables 1 and 2).