Christine Morand1, Helmut Sies2. 1. INRA, UMR 1019, Human Nutrition Unit, Centre de Recherche Auvergne-Rhone-Alpes, F-63122 Saint-Genès-Champanelle, France. Electronic address: christine.morand@clermont.inra.fr. 2. Heinrich-Heine-Universitaet Duesseldorf, Institute for Biochemistry and Molecular Biology I, D-40225 Duesseldorf, Germany. Electronic address: sies@uni-duesseldorf.de.