Propolis is the focus of a large number of research projects. Some preliminary research findings (published in the biomedical literature), together with their limitations, are described below. Readers are reminded that the following information represents preliminary research and does not constitute medical advice. Readers are directed to their local physician or healthcare provider for medical advice.
As an antimicrobial
Preliminary scientific studies show some types of propolis have in vitro antibacterial and antifungal activity (with active constituents including flavonoids like galangin and hydroxycinnamic acids like caffeic acid). In the absence of any in vivo or clinical studies however, it is not clear if this antimicrobial activity has any therapeutic relevance.
As an emollient
Preliminary in vivo studies with rats suggest propolis may be effective in treating the inflammatory component of skin burns. Also, a clinical trial has shown Brazilian propolis skin cream to be superior to silver sulfadiazine for the treatment of partial thickness burn wounds. Recent studies have raised concerns about the efficacy of silver sulfadiazine however, with suggestions it may actually delay wound healing. Further clinical research is needed.
As an immunomodulator
Propolis has been reported to exhibit both immunosuppressive and immunostimulant effects. Further research is needed to establish if there is a practical application for these seemingly opposing pharmacological effects.
As a treatment for allergies
Though claims have been made for the use of propolis in treating allergies, propolis can itself cause severe allergic reactions if the user is sensitive to bees or bee products.
As an oral hygiene product
Propolis has been the subject of recent dentistry research, and there is some in vivo and clinical evidence that propolis might protect against dental caries and other forms of oral disease, due to its antimicrobial properties. Propolis is also being investigated for its efficacy in the treatment of canker sores and in reducing the inflammation associated with canal debridement and endodontic procedures.
As an antioxidant
One in vivo study has shown that propolis reduced the chances of cataracts in rat pups. Again however, in the absence of any clinical studies, it is not clear if this activity has any therapeutic relevance.
In cancer treatment and cancer prevention
In in vitro tests, propolis induces cell cycle arrest, apoptosis and reduces expression of growth and transcription factors, including NF-κB. Notably, caffeic acid phenethyl ester down-regulates the mdr-1 gene, considered responsible for the resistance of cancer cells to chemotherapeutic agents. In in vivo studies with mice, propolis inhibits 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced tumorigenesis. Again however, in the absence of any clinical studies, it is not clear if this activity has any therapeutic relevance.