Everything there is to know about propolis
Propolis is a 100% natural, antimicrobial substance made from plant resins, which is collected by honeybees (Apis mellifera) along with the nectar and pollen they need for food. It is also known as 'bee glue' and sometimes as 'hive dross'.
Sticky at or above room temperature (20-25 degrees Celsius) whilst hard and brittle below these readings, this resinous mixture has been used by humans for hundreds of years for a range of medical purposes, due to its antiviral, antibacterial, anti-inflammatory, anaesthetic and regenerative properties.
Depending on the type of plants where the bees have harvested the resin, in its crude form propolis can be brown, green, red, or black in colour. Bees farmed in a specific region of Canada, where they mainly have access to poplar trees (Populus sp.), produce brown propolis.
In temperate climates, bees tend to use poplar trees as their source of resins, whereas in more tropical climates they mainly visit Clusia minor and Clusia rosea flowers, as well as plants from the Asteraceae (aka Compositae) family, which include Baccharis dracuncufolia and wild Rosemary. There are more than 25,000 other species of Asteraceae worldwide.
How is propolis made?
Honeybees, which are native to Europe, Western Asia, and Africa, must collect nectar which they convert to honey (they do this by breaking down the complex sugars within it using enzymes in their mouths) and eat it as a source of carbohydrates. They also consume pollen to gain important proteins. However, they also make special separate journeys where they only collect plant resins which they do not use for food.
Resins are secreted by plants when they have been damaged, in order to close wounds in their surfaces and protect the plant from further damage or from insect attacks. They are also produced to protect new buds from free radicals. In effect, resins are a plant’s equivalent of our white blood cells or immune system.
The bees pick up the resins using their forelegs and mandibles (part of the insect's mouth), and then place it in the corbiculae (pollen sacs) on their hind legs. They can carry about 10mg of resin in each sac.
Once they get back to the hive, other bees have to pull the sticky substance off of their legs for them, before mixing the plant resins with their saliva and wax which is secreted by worker bees from eight wax-producing glands on their abdomens.
They mix these substances together by chewing on them. The result is raw propolis.
What do bees use it for?
Bees place propolis at the entrance to their hive, using its antimicrobial properties to disinfect the base of their legs (made up of a soft pad called the arolium, and claws). This keeps them from bringing in harmful microbes. Moreover, worker bees use propolis to prepare a sterile place for their queen to lay her eggs.
Another important role fulfilled by this substance was revealed in a book published in 1965 by Hoyt M. entitled The World of Bees. In his work he stated that he had found, in an apiary at the University of Minnesota, USA, a dead mouse mummified in propolis.
Since then, the practice of embalming parasites and pests, such as beetles and other small predators which bees find too difficult to remove from the hive once they have been killed by stinging them, has been observed many times. By covering these dead intruders with propolis, the bees prevent corpses from decomposing and presenting a health risk to the colony.
Propolis is also used by bees to patch up holes and cracks in the hive to keep heat from escaping, better protect the colony from invasion by other animals, as well as to strengthen the wax honeycomb structure which contains their larvae and food stores.
Observations of bees over the years have determined that they only use pure propolis to fill gaps in their hive which measure from 0.1 to 3.5mm. Larger gaps are filled with a mixture of propolis and wax, or wax alone.
What do humans use it for?
Propolis possesses many beneficial properties, such as the ability to reduce sensations of pain, fight against viruses and help the regeneration of damaged tissue.
As a result, it is used in many commercially available cosmetic and medicinal products, such as ointments and creams, nasal sprays, throat lozenges, and toothpaste. Some studies even suggest that it could help to improve cancer treatments and treat allergies (although not allergies to bees or bee products).
It is also used as a component of some varnishes, an ingredient of chewing gum, in car wax products, and in the manufacture of violins to enhance the appearance of the wood-grain.
It is likely that many other uses for propolis will be found as technologies, scientific knowledge, and research methods improve.
How is it processed for commercial use?
The amount of propolis created by a hive will depend on many factors, such as the bee breed, geographic and climate conditions, the type of hive provided by the bee farmers, the presence of resin sources in the area, and the strength of the colony.
Most propolis-collecting devices used by bee farmers, are designed to make use of the fact that bees tend to fill only small cracks with pure propolis. Wooden or plastic framework is built especially so that it can be easily removed and replaced once the bees have sealed the gaps.
Raw propolis is scraped off of the collection device and inspected for impurities, which can be removed by hand, such as small stones, other debris, wax, and honey. After this process has taken place, the propolis is cleaned and purified by machines so that smaller impurities, which might include traces of heavy metals or pesticides, are removed.
Finally, tests are undertaken to make sure that nothing else remains in the propolis which should not be there, and the substance can then be used in the manufacture of various products.
Propolis is such a stable material that, as long as it is kept in the dark in sealed containers, it can be stored for years without degrading or losing its useful properties.
Propolis has been used for hundreds of years for medicinal purposes, stretching back at least as far as 300 BC, when the ancient Egyptians and Greeks used it as an antiseptic. The Egyptians also used propolis in parts of their embalming process, for instance to coat the mummification bandages.
Hippocrates (460 BC-377 BC), who is largely accepted as the father of modern medicine, wrote about the properties of propolis during his time as a physician. He used it as a cure for many ailments, such as internal and external sores and ulcers, as well as employing it to relieve pain and reduce swelling in patients.
In more recent history, scientists have tried to improve on propolis, but they have not been successful. It seems the bees know best.
What are the chemical properties of propolis?
The chemical properties of propolis vary depending on which plants the bees collect resins from, the geographical positioning of these plants, and the season. The composition of the soil, the weather, as well as each plant's biological make-up, will have an effect on the components of the resin.
At a basic level, propolis contains plant resins, vegetable balsams, wax, essential oils, pollen, and bee saliva; however, a more complex examination reveals a variety of different active compounds, some of which have antimicrobial and antiseptic properties.
In a publication of the Journal of Membrane Science, a paper entitled Extraction of biologically active compounds from propolis and concentration of extract by nanofiltration states that more than 300 compounds have been found in raw propolis. Flavones, flavonols, flavanones, (which are responsible for the red, orange and yellow colours in fruit and autumn leaves), as well as phenolic acids and dihydroflavonols, are but a few.
There are about 20 million unique possible chemical combinations for propolis.