A team of scientists led by Professor Rose Cooper, at the University of Wales Institute, Cardiff (UWIC), have been studying how manuka honey interacts with the three types of bacteria that commonly infect wounds, including the notorious antibiotic-resistant MRSA. At the Society for General Microbiology Spring Conference 2011, held in Harrogate earlier this year, Cooper and her team reported that the honey interferes with bacterial growth in a number of important ways, and may even be able to reverse the resistance to antibiotics.
Crucially, manuka honey was found to prevent the attachment of bacteria to tissues, an essential step in the infective process. In addition, it also blocks the formation of biofilms, which protect bacteria against antibiotics and allow them to cause chronic, persistent infections. Even more exciting, they reported that the honey can make MRSA more sensitive to antibiotics such as oxacillin-thereby effectively reversing the antibiotic resistance.
"This indicates that existing antibiotics may be more effective against drug-resistant infections if used in combination with manuka honey," Professor Cooper said.
The evidence also suggests that manuka honey has genuine potential as a natural, topical alternative to antibiotics for fighting infection. In fact, a number of hospitals have been successfully using manuka-honey-impregnated dressings for wound care for years (Br J Oral Maxillofac Surg, 2008; 46: 55-6).
In a small trial carried out by the Children's Hospital Medical Centre at the University of Bonn, Germany, full healing was achieved with manuka honey in seven consecutive patients whose wounds were either infected or colonized by MRSA. "Antiseptics and antibiotics had previously failed to eradicate the clinical signs of infection," the researchers said (J Wound Care, 2007; 16: 325-8).
In a larger, multicentre, randomized and controlled trial carried out in Dublin, Ireland, 108 patients with chronic venous leg ulcers were treated with either manuka honey or a commonly used hydrogel for advanced wounds. At the start of the study, MRSA was identified in 16 of the wounds-10 in the honey group and six in the gel group. After four weeks, 70 per cent of the manuka-honey-treated wounds vs only 16 per cent of the hydrogel-treated wounds showed eradication of MRSA (J Wound Care, 2008; 17: 241-4, 246-7).
The same researchers later reported that, after 12 weeks, the manuka-honey group had a higher incidence of healing and a lower incidence of infection than the gel-treated group (J Clin Nurs, 2009; 18: 466-74).
A unique honey
All honey has antibacterial activity to some extent, mainly due to the hydrogen peroxide formed by the enzyme glucose oxidase, which bees add to the nectar to make honey. However, manuka honey-made by bees that feed on the flowers of the manuka bush (or tea tree), native to New Zealand and Australia-contains a high level of additional non-peroxide antibacterial components (J Pharm Pharmacol, 1991; 43: 817-22). It is this non-peroxide activity that is known as the 'Unique Manuka Factor' (UMF), although not all of the honey sold as manuka honey has this type of antibacterial activity. Indeed, the honey used in the MRSA research was medical-grade manuka honey, not the stuff you can buy in the supermarket.
The importance of this non-peroxide anti-bacterial activity is that it's not affected by the catalase enzyme present in body tissues and the blood that breaks down hydrogen peroxide, the major antibacterial factor found in other types of honey. If a honey without this type of action were used to treat an infection, the potency of its antibacterial action would likely be reduced because of the action of catalase (PLoS One, 2011; 6: e18229). Moreover, while the enzyme that produces hydrogen peroxide in honey is destroyed when honey is exposed to heat and light, the non-peroxide antibacterial activity of manuka honey is stable, so there are no concerns that UMF honey will lose its activity during storage.
Nonetheless, there don't appear to be any clinical trials comparing the use of manuka and other types of honey in wound care.
In addition to antibacterial properties, manuka honey also appears to have "clinically relevant" anti-inflammatory activity (Innate Immun, 2011 Oct 6; Epub ahead of print). Precisely what is responsible for this activity is not yet known, but it could explain why the honey has proven useful against a number of inflammatory conditions.
Most recently, the results of a phase-II study reported at the 2011 European Multidisciplinary Cancer Congress (EMCC), held in Stockholm in September, showed that topical manuka honey may help to prevent the radiation-induced dermatitis (an inflammatory skin reaction) seen in breast-cancer patients. The controlled trial found a lower incidence of grade-2 or higher dermatitis in the honey-treated group compared with the group using aqueous cream.
Taken as a chewable 'honey leather', manuka honey rated at UMF 15 has also been shown to significantly reduce gingivitis-inflammation of the gums-compared with chewing sugar-free gum (J Int Acad Periodontol, 2004; 6: 63-7).
What's more, according to a study done in India, manuka honey may even have a role to play in treating inflammatory bowel conditions. In a rat model of experimentally induced inflammatory bowel disease, an oral dose of manuka honey significantly reduced colonic inflammation (Phytother Res, 2008; 22: 1511-9). However, human trials are needed to confirm these results.
The future looks sweet
As research on manuka continues to flourish, we'll no doubt be hearing a lot more about the benefits and mechanisms behind this unique honey. Waikato University in New Zealand, for example, is looking into the antioxidant level of manuka and other honeys, which could lead to new research into exciting areas such as anti-ageing.
For now, however, manuka honey is indeed proving itself to be a viable alternative to the increasingly redundant army of antibiotics.
Factfile: A new honey hero?
A new type of 'active' honey has hit the shelves in the UK amidst claims that it can reverse signs of ageing by up to 10 years. Active Chilean Rainforest Honey, made by the Active Honey Company, is a blend of ulmo, tineo and quillay tree honey from the rainforests of southern Chile. It's now available in Boots and healthfood stores such as Holland & Barrett, and the Internet is abuzz with reports that it's a wonder product for the skin. Used as a face mask, it supposedly can smooth fine lines and tighten the skin.
Sadly, however, there are no clinical studies to support these claims. The company's website, in a section called 'The Science', cites a study of ulmo honey's antimicrobial ability. Impressively, this found that the honey displayed greater antibacterial activity against MRSA than did maunka honey (BMC Complement Altern Med, 2010; 10: 47; doi: 10.1186/1472-6882-10-47). However, this activity was largely due to hydrogen-peroxide production, the researchers found; the honey doesn't appear to possess the non-peroxide antibacterial activity that makes manuka particularly effective (see main text). Nevertheless, antibacterial activity aside, the study still says nothing about the honey's skin-tightening, anti-ageing potential.
According to an article in The Daily Mail, users of the honey have reported looking 10 years younger after just a few weeks' use. These claims have been included in press material, but the company doesn't repeat them on its website. Under new advertising guidelines for the Web, companies must point to proper studies, not anecdotal evidence.
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