Submitted on January 6, 2009
Revised on February 2, 2009
Accepted on February 19, 2009
Phytosterol Glycosides Reduce Cholesterol Absorption in Humans
Xiaobo Lin1, Lina Ma1, Susan B Racette1, Catherine L Anderson Spearie1, and Richard E Ostlund, Jr1*
1 Washington University School of Medicine
* To whom correspondence should be addressed. E-mail: ROstlund{at}dom.wustl.edu.
Dietary phytosterols inhibit intestinal cholesterol absorption and regulate whole-body cholesterol excretion and balance. However, they are biochemically heterogeneous and a portion is glycosylated in some foods with unknown effects on biological activity. We tested the hypothesis that phytosterol glycosides reduce cholesterol absorption in humans. Phytosterol glycosides were extracted and purified from soy lecithin in a novel two-step process. Cholesterol absorption was measured in a series of three single-meal tests given at intervals of two weeks to each of 11 healthy subjects. In a randomized crossover design, participants received approximately 300 mg of added phytosterols in the form of phytosterol glycosides or phytosterol esters, or placebo in a test breakfast also containing 30 mg cholesterol-d7. Cholesterol absorption was estimated by mass spectrometry of plasma cholesterol-d7 enrichment 4-5 days after each test. Compared to the placebo test, phytosterol glycosides reduced cholesterol absorption by 37.6 ± 4.8% (P<0.0001) and phytosterol esters 30.6 ± 3.9% (P=0.0001). These results suggest that natural phytosterol glycosides purified from lecithin are bioactive in humans and should be included in methods of phytosterol analysis and tables of food phytosterol content.
