BACKGROUNDPropolis is a resin made by bees to seal openings in the bee hive and prevent microbial growth. It consists mostly of wax, bee saliva and extracts from plants and trees visited by the bees. The precise composition of propolis varies depending on where and when it is made by the bees.
Propolis is harvested by placing a perforated grid with small openings in a bee hive. The bees fill the perforations with propolis as if they were sealing their hive. The grid is then removed and the propolis collected.
Hippocrates, the ancient Greek physician, wrote about the medicinal value of propolis. It has been used for many different ailments, but primarily as an antiseptic and anti-inflammatory agent, especially for treating wounds and burns. More recent interest has focused on its use in dental care.
Dental caries, or tooth decay, arises after bacteria build up on tooth surfaces leading to dental plaque. If untreated, the bacteria can break down tooth enamel, leading to cavities, pain, tooth loss or, sometimes, more serious infections.
Proper oral hygiene, fluoride products and dental visits can prevent or control dental caries.
Pharmaceutical antimicrobial agents are available for dental caries, but resistance and side effects can develop. This has led to a search for non-toxic, inexpensive ways of treating and preventing dental caries and other types of mouth infections.
EVIDENCE FROM STUDIES
More than 160 different compounds have been isolated from propolis. Over half of these are classed as phenolic compounds or flavonoids, which often have antimicrobial activity. Laboratory tests have confirmed that many compounds in propolis are antibacterial, antifungal or antiviral. A study with rats was the first to notice significantly reduced dental caries after a propolis extract was added to the animals’ drinking water.
Studies in humans have shown that mouthwash containing propolis extract significantly reduced the concentration of bacteria in people’s saliva. Such beneficial effects were found in three small studies, while another study found no benefits.
The researchers believed this was due to the different propolis harvesting in different regions. Most of the research to date has been conducted in Brazil as dental caries is particularly problematic in that region.
Propolis has also been tested against Candida albicans mouth infections. Most people carry this yeast without harmful effects, but under certain conditions it causes opportunistic infections. This can happen under dentures if the person’s immune system is compromised or if the dentures aren’t cleaned adequately.
Two small studies were conducted in Brazil with people wearing dentures who had developed Candida mouth infections. They cleaned their dentures four times daily and applied a propolis gel. Most people’s infections were resolved and their gums healed after seven days. The results were similar to other patients using pharmaceutical gels for such infections.
PROBLEMATIC ASPECTS
No adverse effects were reported in the studies published with dental patients. Other uses of propolis have been reported to cause mild allergic reactions in some people. Those with allergies to bee stings should be cautious about using propolis.
RECOMMENDATIONS
Despite the growing worldwide popularity of propolis in dental hygiene products, relatively few studies have examined its effectiveness. The available evidence is encouraging, and the products are generally safe except for those who are allergic to propolis. The precise composition of propolis varies widely, leading to research into the identification of the most active ingredients or the regions where the most active propolis can be collected.
Dónal O’Mathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics. If you would like to see a particular herbal remedy or food supplement reviewed in a future column, send your request to healthsupplement@irishtimes.com
