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 and zinc all are well documented for their health promoting benefits sambucol is the worlds best selling and most extensively researched black elderberry extract and is produced with a patented process which uniquely isolates the key active constituent of eld