All honey has antibacterial properties thanks in part to naturally occurring Hydrogen Peroxide (H2O2) present in the honey.
Manuka honey has H2O2, but has additional antibacterial properties that exist even when the H2O2 is neutralized.
Prior to 2013, manuka honey was commonly rated according to its antibacterial properties. This was determined by laboratory testing on a well diffusion assay of Staphylococcus Aureus (a bacteria) after the H2O2 was neutralized in the honey sample.
An industry-adopted scale was used to measure its antimicrobial efficacy from <5 (low efficacy) to 20 (high efficacy), with the higher rating indicating higher antibacterial potency. This was called the Non-peroxided activity (NPA) of the honey.
The area of exclusion of bacterial growth due to the honeys antimicrobial potency was measured and compared to a Phenol control (an antiseptic). The results were then referenced back to the equivalent concentration of Phenol. E.g. a manuka honey with an NPA of 15 had the equivalent antimicrobial efficacy of a 15% concentrated solution of the antiseptic Phenol. And so a grading system for manuka honey from 5+ - 25+ was developed.
In 2007 Professor Henle at Dresden university in Germany, demonstrated the non-peroxided activity of manuka honey is directly proportional to the concentration of a compound Methylglyoxal (MG or MGO), present in the honey. Methylglyoxal has strong antiseptic properties. They concluded the majority of the non-peroxided activity was due to the honeys Methylglyoxal concentration.
Methylglyoxal or MGO is used as a grading system by many Manuka honey companies.
Moveover, as MGO is a unique compound found only in Manuka honey, it is also an indicator of the manuka floral origins of the honey. i.e. the honey’s manuka purity.
To get the highest concentrations of MGO, Avatar beekeepers strategically place their hives among the purest manuka forests at just the right times and then they might mature the honey for years to naturally grow the MGO to its optimum concentration.
Methylglyoxal is naturally synthesized from another compound Dihyhydroxyacetone (DHA) found in fresh manuka nectar according to the temperature and time the honey is ‘matured’ in storage.
DHA is a compound unique to Manuka flower nectar. It’s concentration in new honey gives us a good indication of the honeys potential future methylglyoxal concentration. However, the concentration of DHA found in the nectar of manuka flowers has wide variability according to: the manuka species, the region, the season and environmental factors. The DHA (and therefore also MGO) concentration can also be artificially raised by unscrupulous companies by the addition of synthetic DHA to the honey.
That’s why you should always purchase manuka honey from a supplier who uses a rating system that also uses other parameters (e.g. pollen) in addition to MGO concentration to guarantee you are buying a genuine manuka honey product.
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