For over 10 years, I have scientifically investigated what many local New Zealanders have accepted as common wisdom: our local manuka honey is a superior treatment for wounds and infections. Manuka honey is gathered in New Zealand from the manuka bush, Leptospermum scoparium, which grows uncultivated throughout the country. (More recently, as a result of systematic screening of Australian honeys, a honey with the same properties has been found to be produced from Leptospermum polygalifolium, which grows uncultivated in a few parts of Australlia.)

After the results of my work became known through scientific journals, many people contacted me to find out what is so special about active manuka honey. A thorough and scientific response is available in articles listed on my Web site, www.honey.bio.waikato.ac.nz. However, I have compiled the pertinent facts here:

• Approximately 50 reports in medical journals detail the effectiveness of honey as a wound dressing and as therapy for eye infections and diarrhea ^{1, 3}.

• Honey has an antibacterial activity, due primarily to hydrogen peroxide formed in a "slow-release" manner by the enzyme glucose oxidase present in honey, which can vary widely in potency. Some honeys are no more antibacterial than sugar, while others can be diluted more than 100-fold and still halt the growth of bacteria. The difference in potency of antibacterial activity found among the different honeys is more than 100-fold.

• "Active manuka honey" (and its Australian equivalent) is the only honey available for sale that is tested for its antibacterial activity. It contains an additional antibacterial component found only in honey produced from Leptospermum plants: "unique manuka factor" (UMF). There is evidence that the 2 antibacterial components may have a synergistic action.

• Unique manuka factor is not affected by the catalase enzyme present in body tissue and serum. This enzyme will break down, to some degree, the hydrogen peroxide which is the major antibacterial factor found in other types of honey. If a honey without UMF were used to treat an infection, the potency of the honey's antibacterial activity would most likely be reduced because of the action of catalase.

• The enzyme that produces hydrogen peroxide in honey is destroyed when honey is exposed to heat and light. However, UMF is stable, so there is no concern about manuka honey losing its activity in storage.

• Honey with UMF is more effective than that with hydrogen peroxide against some types of bacteria. For example, active mauka honey with UMF is about twice as effective as other honey against Eschericihia coli and Staphylococcus aureus^{4, 5}, the most common causes of infected wounds.

Many medical professionals are using active mauka honey-and getting good results-in patients with wounds that have not responded to standard treatment. For example, a successful trial of active manuka honey on unresponsive skin ulcers was recently published in the New Zealand Medical Journal ⁶. In addition, staff at a large hospital in Brisbane, Australia, recently used active mauka honey as a wound dressing on a patient for whom honey without UMF had failed.

None of the results being obtained clinically should be considered evidence that active manuka honey is more effective than other honey-a comparative clinical trial will be needed to establish that. Nevertheless, when asked, I recommend active mauka honey with a good level of antibacterial activity for management of infections.

Medical professionals in New Zealand use active mauka honey with a rating of 10 UMF or higher. Although good results may be obtained with lower levels of activity, there is a chance that the lower activity will not be enough to fully clear an infection. In addition, honey with a lower level of activity will not allow as much of the antibacterial elements to diffuse into infected tissue, which could mean that effective control of infection may not be achieved in deeper tissue.

To rate the potency of antibacterial activity of honey, I devised the testing method and the UMF number. The UMF numbers come from a standard laboratory test of antibacterial activity, with honey being compared with a standard antiseptic (phenol) for potency. For example, a honey with a UMF rating of 4 would be equivalent to the antiseptic potency of 4% solution of phenol, a carbolic disinfectant; a honey with a rating of 10 would have a potency equivalent to a 10% solution of phenol. To alleviate any concern over the possible risk of introducing infection by the use of an unprocessed natural product on wounds, honey can be sterilised by gamma irradiation without loss of any of its antibacterial activity ⁷.

For information on the use of honey in managing wounds, burns, skin ulcers and necrotising fasciitis, read the article: "The role of honey in the management of wounds" ².