Claims that the MGO(TM) Manuka Honey rating system misrepresents the antibacterial activity of manuka honey were conclusively dismissed today by new scientific research.
According to Active Manuka Honey Association general manager John Rawcliffe the MGO (TM) Manuka Honey system does not fully measure antibacterial activity and therefore is misleading.
AMHA licenses the use of the rival UMF test, which rates manuka honey in comparison to the standard laboratory disinfectant phenol, a test which beekeepers complain is prone to error and has problems with “repeatability”.
Honey health science company Manuka Health New Zealand Ltd, which certifies the level of the active ingredient methylglyoxal, today made scientific research available which proves its MGO™ Manuka Honey system accurately measures antibacterial activity.
Chief executive Kerry Paul said today the research finally settled the issue of whether MGO™ Manuka Honey was valid for commercial labelling purposes. Critics had claimed for years that the antibacterial activity in manuka honey depended on other substances in addition to methylglyoxal.
“The latest research proves conclusively this is not the case,” he said. “The researchers specifically say that methylglyoxal is a valid measure of antibacterial activity.”
The research was conducted by the Institute of Food Chemistry at the Technical University of Dresden, which identified methylglyoxal in 2006 as manuka honey’s dominant antibacterial constituent.
In a peer-reviewed paper published this month in the Czech Journal of Food Sciences, the German researchers show “a perfect linear correlation” between methylglyoxal levels in 61 manuka honey samples and their antibacterial ratings in equivalent phenol concentration.
The authors, Julia Atrott and Professor Thomas Henle, said the purpose of their study was to investigate the extent to which methylglyoxal was responsible for the non-peroxide antibacterial activity of manuka honey.
The research checked whether it was possible to back-reference from methylglyoxal content to the antibacterial properties of a honey sample. The linear correlation showed this was the case.
“This clearly underlines that methylglyoxal is the dominant bioactive compound in manuka honey and above concentr ations of around 150 mg/kg is directly responsible for the characteristic antibacterial properties of manuka honey,” the paper says.
“Methyglyoxal can be a suitable tool for labelling the unique bioactivity of manuka honey.”
Samples for the study were sourced from drums of honey selected on a spread of non-peroxide contents and of varying ages.
Tests for antibacterial activity in the 61 samples were carried out by a specially-appointed laboratory using criteria laid down by the Honey Research Unit at the University of Waikato.
The researchers said their results were in perfect agreement with a 2008 University of Waikato study which reported methylglyoxal levels and antibacterial results for 49 samples.
“This remarkable agreement of results obtained in two independent studies clearly underlines the final statement that methylglyoxal is the dominant bioactive compound in Manuka honey and starting from concentrations of approximately 150 mg/kg is exclusively responsible for the pronounced antibacterial activity.”
“Due to limited sensitivity and inaccuracy of the test system used, data obtained for antibacterial activities below 10 % equivalent phenol concentration must be handled with care . . . for such low antibacterial activities, other factors such as polyphenols, organic acids or currently unknown compounds may additionally contribute to non-peroxide antibacterial properties.
“In conclusion, methylglyoxal is a unique antibacterial compound found in high concentrations in manuka honeys from New Zealand and directly responsible for the specific antibacterial activity of these samples.
“Methylglyoxal can serve as a suitable tool for the labelling of the bioactivity of commercial products.”
Manuka Health moved two years ago to certify the active ingredient in its manuka honey products by establishing the MGO™ Manuka Honey rating system.
Mr Paul said consumers easily understood the concept of active ingredient but never grasped the relevance of the UMF test, which in any case had been found to vary by more than 25% in repeat tests of the same sample.
“Some in the manuka honey industry want to stick with an inaccurate and unreliable test from which even the original developer has dissociated himself,” he said.
“Meanwhile, we have had our system in the marketplace for two years – based on a highly-accurate test for the active ingredient.”
Mr Paul said information about the latest research was available online at www.mgomanuka.com and on the company’s website www.manukahealth.co.nz
For further information and a copy of the research paper, please contact:
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