Researchers at the University of Sydney compared the effectiveness of manuka honey of different UMF (unique manuka factor) ratings (ranging from 5 to 20 depending on antibacterial activity) and ordinary, store-bought honey in healing large, bloody wounds on horses' legs.

They said the results were "quite remarkable" and applicable to humans.

"I have been doing wound-healing studies for many years and if you look across the board there are very few, if any, compounds that have a consistent repeatable effect," Sydney University equine surgical specialist Andrew Dart said.

"The wound treated daily with UMF 20 honey showed a nice pink, even and healthy bed of granulation of tissue, whereas our control had a rough, unhealthy bed of granulation tissue with a necrotic centre with poor blood supply."

The study, published in the Australian Veterinary Journal, is further proof that manuka honey, which is produced by bees from the manuka or tea-tree bush and has antibacterial properties, deserves its reputation as a powerful healing agent.

The higher the UMF, the greater the antibacterial activity, as well as the price.

The research found that wounds treated with UMF 20 honey daily for as little as 12 days healed faster than wounds treated with regular honey and untreated wounds.

In fact, wounds treated with generic honey did not heal better than untreated wounds. UMF 5 honey did have some positive impact.

Professor Dart said regular honey was usually heat treated and stored in unfavourable conditions, so its performance varied.

"The cost of it is an issue for a lot of people and there's a lot of rumours that you can just use plain honey, but the longer they sit around on shelves, particularly if they're heat treated, the more likely those antibacterial properties are lost," he said.

"There's also manuka honey out there that hasn't been graded, and because you don't know, it may not have as good an effect as graded products."

Shona Blair, a microbiologist at University of Technology, Sydney, warned consumers to be cautious, saying it was well known that there are manuka honey-labelled products of questionable quality on the market.

In regards to wound healing, she urged people to buy properly packaged manuka honey that was registered with the Therapeutic Goods Administration.

"There's a huge difference if the labelling is accurate - UMF 20 honey is four times more powerful and active against golden staph than UMF 5 honey," Dr Blair said. It was a "fantastic" dressing for wounds, leg ulcers, pressure sores, and even acne and nappy rashes.

Nural Cokcetin, a researcher at the University of Technology, Sydney, said honey-based wound-care products registered with the TGA included honey-impregnated bandages, gels and creams.

"Honey works really well on lots of different types of wounds - infected, acute, chronic, or even burns and ulcers and certain honeys may work better on some wound types compared to others," she said.

"For example, for an infected wound we would always use a honey that has high levels antimicrobial activity, but for a non-infected ulcer, you are likely to still see the wound-healing properties of honey even if it does not have high levels of antimicrobial activity," Dr Cokcetin said.

The research was not funded by any outside sources.