Propolis and Its Uses

Propolis (bee glue, hive glue) is the sticky substance honey bees make by mixing resins collected from tree buds and plant wounds with beeswax and secretions, and use in the hive to seal cracks and coat surfaces. It has shown clear antimicrobial effects in laboratory studies; however, evidence of a therapeutic effect in humans is limited, and its composition varies greatly from region to region. Propolis is a known contact allergen; care is needed the first time it is used.

What is propolis and what do bees use it for?

Foragers collect resin from the buds and bark wounds of trees such as poplar, birch, chestnut and pine, and carry it back to the hive on their hind legs, like pollen. In the hive, other bees chew this resin, mix it with beeswax and smear it where it is needed.

• Sealing cracks and gaps: Gaps around the lid, frame lugs and box joints are filled with propolis.
• Narrowing the entrance: Especially in autumn, the entrance may be narrowed with propolis.
• Coating surfaces: In natural nests the inside surfaces are coated with a thin layer of propolis.
• Keeping the hive clean: Intruders too large to be carried out (e.g. a mouse) are coated in propolis, limiting their decay.

Researchers think that propolis plays a role in the colony's collective defence against microorganisms. This observation is also the starting point for research into human use.

The composition of propolis: why isn't all propolis the same?

The composition of propolis depends on the plant from which the bees collect resin. In temperate regions the main source is poplar buds; this type of propolis is rich in flavonoids and phenolic acid esters. Products from other regions, such as Brazil's green propolis, contain completely different components. In Türkiye too there are different types of propolis depending on the region and vegetation.

Raw propolis consists roughly of resins and balsams, beeswax, essential oils, pollen and other substances; the proportions vary from source to source. This has two important consequences:

• The results of research carried out in one country do not apply directly to propolis from another region.
• General claims of the "propolis is good for such-and-such" kind cannot be defended scientifically; the questions of which propolis, which extract and what amount remain unanswered.

That is why serious producers record the collection area and period, and have each batch analysed if possible.

How is propolis collected? Step by step

The cleanest propolis is collected with a propolis screen (trap). This is a thin plastic or wire sheet with narrow slits, laid over the frames under the lid. The bees fill the slits with propolis because light and air come through them.

1. Put the screen in place: On strong colonies, lay it over the frames at the time of year when bees collect propolis, such as late summer and early autumn.
2. Wait for it to fill: Remove the screen when the bees have filled most of the slits.
3. Freeze it: Put the screen in a bag and leave it in a deep freezer; propolis becomes brittle in the cold.
4. Break it off: Flex or rub the frozen screen so that the propolis drops into a clean container.
5. Clean it: Pick out bee fragments, wax and bits of wood.
6. Store it: Keep it in a cool, dark, airtight container.

What does raw propolis look like?

Good-quality raw propolis has a characteristic resinous, spicy smell. Propolis with too much wax is lighter in colour and waxy; a product containing a lot of foreign matter is of low quality.

How is propolis used? Types of extract

Propolis dissolves very little in water, so it is usually made into an extract. Each solvent draws out different components in different proportions:

• Alcoholic extract (tincture): The most common form, and good at extracting phenolic components. Because it contains alcohol, it may not be suitable for children, pregnant women and people who should not take alcohol.
• Aqueous and glycol extracts: Alcohol-free options; their component profile differs from that of alcoholic extract.
• Oil extracts and ointments: Used in skin products.
• Mouth sprays, lozenges, toothpaste: Commercial forms prepared for use in the mouth.

The strength and cleanliness of home-made extracts are unknown. For products used for health purposes, choose products that comply with regulations and whose contents and production conditions are known.

What is propolis good for? The state of the evidence

Propolis is one of the most studied bee products in the laboratory. Its extracts have been shown under laboratory conditions to be effective against various bacteria, fungi and viruses. There are also small clinical studies in some areas, such as oral health and cold sores.

However, most of these studies are small, short-term and carried out with different types of propolis; the results cannot be transferred from one to another. The correct statement should therefore be "there are preliminary findings, but the evidence is limited". Propolis is not used in place of the treatment a doctor recommends for infections.

Propolis allergy: who should be careful?

Propolis is well known among substances that cause skin allergy. The most common picture is contact dermatitis: redness, itching, blisters and scaling. Sores and swelling of the lips and the lining of the mouth have been reported with oral products; more severe reactions can also occur with swallowed products.

• Testing before first use: Trying it on a small patch of skin is a common approach, but a single test does not rule out sensitisation in the future.
• Who should not use it: People known to be allergic to bee products, poplar buds or certain cosmetic balsams. People with asthma and a history of allergy should consult a doctor.
• For beekeepers: Beekeepers who handle propolis often can become sensitised over time. Wearing gloves is wise, especially when cleaning screens and processing propolis.

Common mistakes

• Adding propolis scraped from painted hive surfaces to food products.
• Leaving the screen in the hive during treatments.
• Leaving propolis uncovered in a warm, bright place.
• Using treatment claims such as "replaces antibiotics" or "kills viruses" in product promotion; food labelling legislation prohibits such claims.
• Leaving the allergy warning off the label.