Propolis is a natural substance collected by honey bees from poplar trees. For 40 million years, bees have been using propolis in their hives to protect them from contamination. Source Naturals found a pure and potent propolis available in the cold, unpolluted environment of the northern United States. Our propolis is rich in bioflavonoids, vitamins, minerals and organic acids, and is naturally processed, without heat or chemicals.