Propolis is a resinous material the bees gather from plants and mix with wax and their own secretions. In the hive it seals gaps, coats surfaces and limits microbial growth.

The problem of variation

This is the most important thing to understand about propolis. Its composition depends on the source plants and therefore differs markedly from region to region.

Poplar-derived propolis, common in temperate regions, differs chemically from tropical types. The practical consequence: a study carried out on one propolis does not necessarily apply to another.

This is also why standardisation is difficult and why results are inconsistent.

What is reasonably supported

• Antimicrobial activity in the laboratory: Consistently demonstrated against a range of organisms
• Antioxidant compounds: Present and measurable
• Local use in the mouth and throat: Some studies indicate benefit

Laboratory activity and effect in the body are different questions. Most of the evidence is at the laboratory stage.

Where evidence is limited

Claims about systemic effects, serious disease and immunity rest on limited evidence. Variation in composition makes results hard to generalise.

Safety

• Contact allergy: Propolis is among the substances that cause contact allergy. Reactions on the skin and in the mouth are reported
• Beekeepers are exposed regularly; wearing gloves is sensible
• Alcohol extracts: Not suitable for children or for people avoiding alcohol
• Pregnancy, chronic illness and regular medication: Consult a doctor

Quality

The method of collection determines quality:

• Screen-collected: Clean; free of timber and paint contamination
• Scraped: Contains wax, timber fragments and paint residue; low quality

Propolis from hives treated with acaricides may carry residues. Screens should be removed during treatment periods.

Storage

Cool, dark and airtight. Light and heat degrade its components. It keeps well in a freezer, and being cold also makes it easier to work with.

Records

Because composition depends on the source plants, recording the region, the source vegetation and the harvest period is genuinely useful information — for the buyer as much as for the producer.