Professor Peter Molan, Honey Research Unit, University of Waikato in New Zealand, looks at the use of manuka honey as a medicine.

Honey has been used for thousands of years to treat wounds, gastroenteritis and eye infections. It was displaced from common usage by the advent of antibiotics in the 1940s. But now that the widespread and rapidly increasing resistance of microbes to antibiotics has become a major global threat to health, there has been a renaissance in the use of honey to treat infections.

The ancient physicians were aware that some honeys were better than others for treating infections, but this ancient wisdom has survived only in folk medicine. It was through scientific investigation following up such folk knowledge in New Zealand that manuka honey was discovered to have a unique anti-microbial component additional to the enzymically produced hydrogen peroxide that is responsible for the anti-microbial activity of all honey. This unique anti-microbial activity is of extremely broad spectrum and is equally as effective against antibiotic resistant strains of bacteria as it is against other strains. Also, unlike other topical anti-microbial agents used on wounds, manuka honey does not slow the healing process by having adverse effects on the exposed wound tissue.

A large amount of clinical experience has shown that manuka honey, selected to have a high level of this unique antibacterial activity, gives rapid clearance of infection from heavily infected wounds not responding to other treatment, and gives rapid healing of chronic wounds not responding to any other treatment. Many case reports from this work have been published, including a small pilot trial. A very large multi-centre, randomised, controlled clinical trial of many honey dressings on leg ulcers, funded by the New Zealand Government, has nearly been completed (see http://www.ctru.auckland.ac.nz/research/halt/).

In view of this evidence for the effectiveness of honey in healing infected wounds, and that from several randomised, controlled trials demonstrating that honey protects burns from becoming infected, it has been proposed that honey be used prophylacticly on hospital patients at risk of acquiring infection through 'superbugs'. Many laboratory studies have shown that manuka honey has a potent antibacterial action against MRSA, VRE, ESBL strains of various species, Acinetobacter baumannii, Stenotrophomonas maltophilia, and other species such as Pseudomonads and coagulase-negative Staphylococci that are difficult to control because of antibiotic resistance. The most common routes of infection for these bacteria, leading to fatal septicaemia in patients with a weakened immune system, are open wounds and where catheters are inserted into the body. The two trials that have been conducted to test the effectiveness of honey in preventing infection of catheter exit sites have given positive results. This proposal has been tried at Waikato Hospital in New Zealand in a ward with a history of recurrent outbreaks of MRSA infection. Manuka honey dressings have been used on all at-risk patients and there have been no cases of MRSA infection since. Whilst this does not constitute proof of the idea, it does indicate that it warrants further trial. The Department of Health in the UK has been approached with this information as a proposal for dealing with the national problem of hospital acquired infection, but has rejected it on the grounds that manuka honey dressings are not registered specifically for treating infection with MRSA. This is not likely to happen before many more hospital patients die, because the companies involved in marketing honey for medical use are not large enough to be able to afford the high costs involved in getting such registration unless the clinical trials needed are publicly funded.

As well as rapidly clearing infection, honey has been demonstrated in clinical usage to have several other therapeutic actions that are of great benefit. It very rapidly causes pus and dead tissue to lift off messy wounds, so surgical debridement or the use of enzymes (which are generally too expensive to use) are not necessary to get a clean wound bed to allow healing to begin. It actively stimulates the healing process, so that rapid healing occurs and skin grafting is not needed. It rapidly soothes inflammation and thus decreases the exudation of serum from wounds, and decreases swelling and painfulness. Trials are currently being conducted on the use of manuka honey to reduce the inflammation that results from radiotherapy.

The rapid clearance of inflammation in wounds by honey also gives healing without scarring. This is because part of the inflammatory process is the stimulation of fibroblasts to produce scar tissue to repair the wound, and prolonged inflammation gives over-stimulation, so excessive amounts of scar tissue are produced.

One of the factors that has slowed the uptake of the use of honey in clinical practice has been the practical difficulty of handling a very sticky substance that, when it warms up to body temperature, becomes quite watery and runs off wounds. But technology has now been developed that makes honey easy to apply to wounds in the form of manufactured dressings. These are not only convenient to use but also increase the effectiveness of the honey on the wound. Because the water content of honey is strongly bound up with the sugar molecules, there is very little wetting of dressings applied to cover honey on a wound, so much of the honey, when it becomes runny at body temperature, gets squeezed out sideways, leaving very little remaining to
exert its therapeutic effects. If, however, the dressing is impregnated with honey before it is applied to the wound, then a larger amount of honey can be kept on the wound. There are two wound dressings impregnated with manuka honey on sale in the UK. One consists of a triple layer of low adherent knitted viscose impregnated with manuka honey. The other consists of a mechanically bonded M-type calcium alginate fibre dressing impregnated with manuka honey. The calcium alginate fibres convert to a sodium alginate gel when wound exudate is absorbed, which has the advantage when used on an exuding wound of not only containing the exudate cleanly within the dressing but also of preventing the honey from being flushed out of the dressings, as can happen with the viscose dressings. Both of these types of dressing are CE marked products. A further development, expected to be on sale in 2006, consists of manuka honey gelled with sodium alginate in the form of a sheet of non-sticky, rubbery material that has a very large capacity to absorb wound exudate.

Means of conveniently using honey in other applications have also been developed, such as skin creams, eye ointment and eye drops. Skin cream made with manuka honey is showing good results when used on radiotherapy burns, and on dermatitis where the combination of the antibacterial activity with the moisturising effect of honey on skin is beneficial. The use of honey in ophthalmology was recorded by the ancient Egyptians and there are many reports in present day medical journals of good results being achieved.

Another traditional use for honey, and where there are reports in present day medical journals of good results being achieved, is for the treatment of gastritis and peptic ulcers. Laboratory research has shown that the anti-inflammatory properties of honey are involved in its action, but there is also the possibility that its antibacterial action may be involved, as the bacterium Helicobacter pylori is thought to be a major cause of gastritis and peptic ulcers. Laboratory testing of Helicobacter pylori has shown that its growth is halted by manuka honey at concentrations below 5%, but not by another type of honey with a high level of antibacterial activity due to hydrogen peroxide when this was at a concentration of 40%. Clinical trials have failed to demonstrate that manuka honey clears Helicobacter pylori from the stomach, but one of these trials (double blind) did show that manuka honey gave significant relief of pain, whereas the other honey used did not. However, this could have been due to the anti-inflammatory action, as some preliminary investigations of the effect of honey on leukocytes in cell culture have indicated that manuka honey may have a higher level of anti-inflammatory activity than other honey.

The question of whether it is the antibacterial activity or the anti-inflammatory activity (or both) involved also remains to be answered in the use of manuka honey for the relief of inflammatory bowel conditions. There has been no research carried out on this, but many anecdotal reports of it being effective indicate that maybe some clinical research should be carried out. That the antibacterial activity of honey can be effective in the gut has been demonstrated in a clinical trial published in the British Medical Journal in 1985, where it was reported that honey halved the duration of bacterial diarrhoea.