|
For the past 19 years honey researchers at the University of Waikato have
been investigating what many local New Zealanders have accepted as common
wisdom: our local manuka honey is a superior treatment for wound 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 this work became known through publications in scientific
journals, many people contacted the Honey Research Unit to find out what is so
special about active manuka honey. The pertinent facts are:
o 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.
o "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: what has been called the "Unique Manuka Factor"
(UMF). There is evidence that the two antibacterial components may have a
synergistic action.
o UMF 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.
o The enzyme that produces hydrogen peroxide in honey is destroyed when honey is
exposed to heat and light. But UMF is stable, so there is no concern about
manuka honey losing its activity in storage.
o The enzyme that produces hydrogen peroxide in honey becomes active only when
honey is diluted. But UMF is active in full strength honey, which will provide a
more potent antibacterial action diffusing into the depth of infected tissues.
o The enzyme that produces hydrogen peroxide in honey needs oxygen to be
available for the reaction, so may not work under wound dressings or in wound
cavities. Honey with UMF is active in all situations.
o The enzyme that produces hydrogen peroxide in honey becomes active only when
the acidity of honey is neutralised by body fluids, but then the honey is
diluted.
o The enzyme that produces hydrogen peroxide in honey could be destroyed by the
protein-digesting enzymes that are in wound fluids.
o The UMF antibacterial activity diffuses deeper into skin tissues than does the
hydrogen peroxide from other types of honey.
o Honey with UMF is more effective than that with hydrogen peroxide against some
types of bacteria. For example, active manuka honey with UMF is about twice as
effective as other honey against Eschericihia coli and Staphylococcus aureus,
the most common causes of infected wounds.
Many medical professionals are using active manuka 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. In addition,
staff at a large hospital in Brisbane, Australia, recently used active manuka
honey as a wound dressing on a patient for whom honey without UMF had failed. In
other hospitals clinicians have likewise noted improvement in healing rates when
changing from other honey to a manuka honey with a good level of UMF.
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, there are good theoretical
reasons for choosing to use active manuka honey with a good level of UMF for
management of wound infections.
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, also known as carbolic) for potency. For example, a honey with a UMF
rating of 4 would be equivalent to the antiseptic potency of 4% solution of
phenol, as used as carbolic disinfectant; a honey with a rating of 10 would have
a potency equivalent to a 10% solution of phenol.
Medical professionals in New Zealand use active manuka honey with a rating of
UMF 10 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 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. Avctive
manuka honey and the Australian Leptospermum honey are commercially available
sterilised in this way.
Continue
|
