Traditionally used coffee grounds - the muck left behind in your percolator after brewing coffee -have been considered as wastes and thrown away or occasionally used as garden fertilizer . Now scientists have reported that these residues are a valuable source of bioactive compounds for producing dietary supplements. Millions of coffee cups are consumed every day around the world generating about 20 million tonnes of used grounds annually in restaurants and cafeterias and also at domestic levels says the report. The new report in the American Chemical Society's Journal of Agricultural and Food Chemistry by Maria-Paz de Pena and colleagues