Hypocholesterolemic effect of Nostoc commune var. sphaeroides Kützing, an edible blue-green alga

Authors

Heather E. Rasmussen, University of Nebraska-LincolnFollow
Kara R. Blobaum, University of Nebraska-Lincoln
Elliot D. Jesch, University of Nebraska-LincolnFollow
Chai Siah Ku, University of Nebraska-Lincoln
Young-Ki Park, University of Nebraska-Lincoln
Fan Lu, Algaen Corporation
Timothy P. Carr, University of Nebraska-LincolnFollow
Ji-Young Li, University of Nebraska-Lincoln

Date of this Version

10-2009

Citation

European Journal of Nutrition 48:7 (October 2009), pp. 387–394.

doi: 10.1007/s00394-009-0025-y

Comments

Copyright © 2009 Springer-Verlag. Used by permission.

Abstract

Background Intake of an edible blue-green alga Nostoc commune var. sphaeroides Kützing (N. commune) has been shown to lower plasma total cholesterol concentration, but the mechanisms behind the hypocholesterolemic effect have not been elucidated. Aim of the study To elucidate the mechanisms underlying the cholesterol-lowering effect of N. commune in mice. Methods Male C57BL/6J mice were fed the AIN-93 M diet supplemented with 0 or 5% (wt/wt) dried N. commune for 4 weeks. Lipid levels in the plasma and liver, intestinal cholesterol absorption, and fecal sterol excretion were measured. Expression of hepatic and intestinal genes involved in cholesterol metabolism was evaluated by quantitative realtime PCR. Results N. commune supplementation significantly reduced total plasma cholesterol and triglyceride concentrations by ~20% compared to controls. Intestinal cholesterol absorption was significantly decreased, while fecal neutral sterol output was significantly increased in N. commune–fed mice. mRNA levels of the cholesterol transporters such as Niemann Pick C1 Like 1, scavenger receptor class B type 1, ATP-binding cassette transporters G5 and A1 in small intestine were not significantly different between two groups. Hepatic lipid contents including total cholesterol, triglyceride and free cholesterol in N. commune–fed mice were not significantly altered. However, the expression of cholesterol-modulating genes including sterol regulatory element binding protein-2 and 3-hydroxy-3-methylglutaryl coenzyme A reductase were significantly increased in mice fed N. commune. Conclusions N. commune supplementation exerted a hypocholesterolemic effect in mice, largely in part, by reducing intestinal cholesterol absorption and promoting fecal neutral sterol excretion.