Artificial lignification of maize cell walls does not affect in vitro bile acid adsorption

Bile acid adsorption by lignified dietary fiber in the human intestine is proposed as a mechanism for lowering blood cholesterol level and reducing colon cancer risk. In this study, we investigated how the concentration and composition of lignin in fiber influences the in vitro adsorption of primary bile acids (glycocholate, taurocholate, and glycochenodeoxycholate) and a secondary bile acid (deoxycholate). Adsorption studies were performed by incubating nonlignified and artificially lignified maize cell walls (dehydrogenation polymer-cell walls) with bile acids under conditions imitating the small intestine and distal colon. Artificially lignified cell walls had varying but defined lignin concentrations (4.8-19.0%) and compositions (varying from pure guaiacyl to pure syringyl lignins) but a uniform polysaccharide-protein matrix. Adsorption of bile acids by cell walls was in a range of 6-31% (4-26 nmol of bile acids/mg of cell walls), with glycochenodeoxycholate showing the highest adsorption rates. Neither lignin concentration nor lignin composition influenced bile acid adsorption, thus disproving a major role of lignin in bile acid adsorption.