Serum lipoproteins and lecithin: cholesterol acyltransferase (LCAT) activity in hypercholesterolemic subjects given beta-sitosterol.

We studied the effect on the serum LCAT activity and apolipoproteins in ten subjects with primary hypercholesterolemia after treatment with beta-sitosterol. The 2-month administration of beta-sitosterol resulted in an increase of the fractional as well as of the molar esterification rate of the LCAT. These alterations were associated with a decrease of the levels of total, esterified, and unesterified cholesterol, whereas the levels of HDL-cholesterol and the apolipoproteins A-I and B were not affected. We conclude that beta-sitosterol primarily lowers cholesterol-rich lipoproteins with a lower density range than LDL via an accelerated esterification rate of the LCAT enzyme.