Sambucol Immune System Formula is a special formulation of the award winning black elderberry extract developed by worldrenowned virologist, Dr. Madeleine Mumcuoglu. This pleasant tasting syrup also contains echinacea, propolis, vitamin C & zinc. All are well documented for their health promoting benefits. Sambucol is the worlds best selling & most extensively researched black elderberry extract & is produced with a patented process which uniquely isolates the key active constituent of elderberries.