Propolis (from the Greek Pro – defence and polis – city) is used by honey bees to protect and strengthen their hives. It is a resinous, gluey substance containing about 200 different chemicals. The major constituents are from the sticky buds of trees like poplar, birch, elm, beech, alder, horse chestnut and pine in temperate zones but from a range of tropical trees in equatorial regions.
The worker bees masticate it, mix it with beeswax and pollen and use it to line inside surfaces of the hive including the cells where the eggs are laid. Structurally Propolis strengthens the comb and hive. However, by virtue of its anti-fungal, anti-bacterial and anti-viral properties it makes the hive a quite sterile environment; properties that have made it a popular constituent of mouthwashes, toothpaste and various skin creams.
Propolis is available in liquid form or as tablets for internal use. It is also available as a cream.
I always keep propolis in the house because several years ago I used it to clear up an abscess under a tooth and have since used it to clear up boils. The bacteria involved in both abscesses and boils is staphylococcus aureas and if that sounds familiar it is probably because MRSA the super bug that the hospitals have been having a problem with is short for Methycillin Resistant Staphylococcus Aureas.
Propolis has been well researched and its anti-bacterial effects demonstrated. In the Boer War it was mixed with Vaseline and put on wounds to stop infection.
Anti-tumour properties. This is a very exciting area and there is sufficient positive, published research on animals and on tissue culture to justify proper clinical trials. The problem, of course, is that clinical trials have to be financed and drug companies are not willing to finance trials of drugs that cannot be patented.
Most of the research in this area has been done using a chemical called Caffeic Acid Phenyl Ester (normally called CAPE) extracted from propolis. Perhaps the most significant findings are that CAPE is toxic to tumour cells but not to normal cells and that only small doses are required with higher doses not increasing the toxic effect. In addition CAPE has been shown to inhibit the action of many different substances known to cause cancer with the site of this inhibition being pinpointed on the signalling pathway to the genetic material in the cell nucleus.
In tissue culture CAPE has been shown to inhibit the growth and multiplication of human breast cancer cells, certain types of skin melanoma cells, human colon cancer cells, liver and lung cancer cells.
Experiments on rats have shown that regular dietary intake of CAPE suppressed the incidence of artificially induced colon cancers by 15 to 30% and when colon cancers did occur the tumours were 43% smaller than in a control group not taking the extract from propolis. Interestingly, one research group (Chiao C et al, 1995) have suggested that CAPE may be a useful adjunct to chemotherapy in the treatment of certain tumours.
Is it safe? Most of the food we eat contains toxins because the plants have developed them to protect themselves from being eaten and propolis, a plant-based substance, is no exception.
However, all the toxicity tests carried out on propolis have shown that quite enormous doses can be tolerated by test animals without observable effects. The doses taken therapeutically by humans are minute in comparison.
One of the major functions of our liver is to detoxify our intake of food and interestingly propolis has been shown to protect the liver from damage by its strong anti-oxidant activity. This property does have relevance for modern society since one study has shown that it can prevent liver damage due to paracetamol poisoning even when given up to 2 hours after the administration of paracetamol.
On the negative side, skin allergies have been reported from using propolis creams and in one fairly large study (605 patients) 4.2% (25 patients) had allergic reactions. With the increasing use of propolis in therapeutic creams and cosmetics the reports of these allergic reactions are growing whereas formerly such reactions were limited to bee keepers. Extracts from the buds of poplar trees have been used to demonstrate that the allergic sensitivity is due to the plant component of propolis.