|Ostlund, Jr, Richard|
Submitted to: Lipids Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2011
Publication Date: 8/15/2011
Citation: Lin, X., Ma, L., Moreau, R.A., Ostlund, Jr, R.E. 2011. Glycosidic bond cleavage is not required for phytosteryl glycoside-induced reduction of cholesterol absorption in mice. Lipids Journal. 46:701-708. Interpretive Summary: All fruits, vegetables and grains contain major lipids such as edible oils and lesser amounts of other lipids such as vitamin E and plant sterols. Many studies have shown that eating about 2 grams of plant sterols per day reduces the levels of total cholesterol in the blood by 10-15 percent. Most natural foods do not contain enough plant sterols to achieve 2 grams per day, so margarines, orange juices, and other functional foods have been fortified with plant sterols to achieve the necessary dosages. Another common dietary supplement, lecithin from soybeans, contains a type of plant sterol called phytosteryl glycoside. The current study, using mice, was designed to test whether the phytosteryl glycosides from lecithin could lower serum cholesterol in the same way what that other plant sterols have been shown to work. The results indicate that phytosteryl glycosides lower the levels of serum cholesterol to the same degree as other plant sterols, but unlike some other plants sterols they remain intact as they pass through the digestive system. Because the American Heart Association and others have reported that lowering the levels of serum cholesterol by 10-15 percent could reduce the risk for heart disease by 20-30 percent, the results of this research may result in the development of new types of phytosteryl glycoside-based functional foods.
Technical Abstract: Phytosteryl glycosides occur in natural foods but little is known about their metabolism and bioactivity. Purified acylated steryl glycosides (ASG) were compared with phytosteryl esters (PSE) in mice. Animals on a phytosterol-free diet received ASG or PSE by gavage in purified soybean oil along with tracers cholesterol-d7 and sitostanol-d4. In a 3-day fecal recovery study, ASG reduced cholesterol absorption efficiency by 45 +/- 6 percent compared to 40 ± 6 percent observed with PSE. Four hours after gavage plasma and liver cholesterol-d7 levels were reduced 86 percent or more when ASG was present. Liver total phytosterols were unchanged after ASG administration but were significantly increased after PSE. After ASG treatment both ASG and deacylated steryl glycosides (SG) were found in the gut mucosa and lumen. ASG was quantitatively recovered in the stool as SG. These results demonstrate that ASG reduces cholesterol absorption in mice as efficiently as PSE while having little systemic absorption itself. Cleavage of the glycosidic linkage is not required for biological activity of ASG. Phytosteryl glycosides should be included in measurements of bioactive phytosterols.