This article was published on SBS Science in September 2016.
Here's why our local Mānuka honey is so good at fighting bacteria.
Last week, the UN announced their commitment to challenging the substantial threat posed to human and animal health by antibacterial resistance.
Unfortunately, not only are superbugs becoming more abundant, but only one new antibiotic has been discovered in the last 30 years. Thus researchers have been looking in more unusual places for substances that we can use in the fight against increasingly resistant bacteria.
The therapeutic effects of Mānuka honey (produced using pollen from Leptospermum, or tea tree, plant species native to Australia and New Zealand) have long been known. In fact, before the advent of highly potent antibiotics, many types of honey were commonly used to prevent infection - but that's not the same as proven medicine.
In this experiment, treatment of bacterial cultures with Mānuka honey in concentrations as low as 3.3% was successful in significantly reducing biofilm formation over a period of 24-72 hours,
“There’s great potential for it, far greater than what is currently being taken advantage of by health professionals and the public,” says director of the ithree institute at the University of Technology Sydney, Professor Liz Harry. She is no newcomer to the wonders of Mānuka honey.
“We’re interested in encouraging hospitals to use it more and also communicate how it works and why it’s so good.”
The reasons for why it’s ‘so good’ are under scientific investigation, but here’s what we know so far: honey contains hydrogen peroxide, a natural disinfectant. However, even after neutralising the hydrogen peroxide within Mānuka, the honey maintains its antibacterial activity – known as ‘non peroxide activity’.
This activity is attributed to a compound called methyl glyoxal, which can disrupt bacterial DNA and kill the bacteria in the process. Theoretically, methyl glyoxal can also affect mammalian DNA and could therefore be toxic to humans. Mysteriously however, there has never been any evidence of this toxicity, and it is unknown why the honey is only toxic to bacteria, and not us.
Other compounds found within Mānuka honey can also contribute to its activity: these include a number of glycosides and phenolics.
While we know that Mānuka’s antibacterial properties are due to the specific Leptospermum species from which the honey is made, there is huge variability in honey activity and it is unclear whether this can be attributed to soil, climate or plant species.
Although there are still a number of mysteries surrounding Mānuka honey, what is clear is that its antibacterial properties really shouldn’t be ignored for any longer.
“What we really want to do is apply rigorous science to honey. We need to do more pilot studies and clinical trials,” says Harry.
“Scientists are being convinced that we need to look at this further and I think that health professionals need to look at honey seriously as part of wound treatment – not just a last resort.”
An antiseptic weapon
To determine the extent of antibacterial properties in any substance, it needs to be subjected to rigorous testing, and modern scientists and clinicians have been doing just that with Mānuka honey. Indeed, over recent years, evidence in favour of this Australasian product as a germ fighter has been mounting.
For example, a study released today, carried out by scientists at the University of Southampton in the UK, demonstrates that use of Mānuka honey can prevent Escherichia coli and Proteus mirabilis species of bacteria from forming biofilms.
Biofilms are a slimy micro-environment which constitute the perfect conditions for bacterial colonisation; your dental plaque is a good example of a biofilm. Once bacteria find a suitable surface, they can begin to secrete a specific assortment of sugars and amino acids amongst which they can dwell. Sometimes problematically, these surfaces can include wounds and implanted medical devices, such as catheters. Biofilms are also notoriously resistant to antibiotics.