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Honey companies knew UMF test was inaccurate

Honey companies knew UMF test was inaccurate

Thursday, May 29, 2008. —

Manuka honey companies which rely on the UMF test for anti-bacterial activity have known for five years it is inaccurate and unreliable.

A newspaper distributed today across the manuka honey industry reveals the UMF test is “not repeatable”, with results from multiple tests on the same sample varying by up to 50%.

The UMF (unique manuka factor) test is the basis of domestic and export manuka honey and honey product markets worth more than $100 million a year.

The Manuka Expose´ newspaper publishes excerpts from minutes of a meeting of the Active Manuka Honey Association and a letter to AMHA from the testing laboratory which show test problems were known to honey companies in 2003.

Manuka Expose´ is published by Manuka Health New Zealand Ltd which uses the recently-discovered active ingredient methylglyoxal to measure anti-bacterial strength.

When Manuka Health launched MGO™ manuka honey earlier this year, AMHA invalidly terminated the company’s membership and revoked its licence to use the UMF brand.

In an article headed “Test lab, producers knew of UMF errors” the tabloid paper says the UMF test is based on an agar diffusion technique “used as a screening method to give a general classification of anti-bacterial activity”.

“Micobiologists never use the method as a precise measurement,” the paper says. “Because of the variation inherent in the technique, results are normally interpreted as part of a range.”

“Despite this, AMHA adopted UMF as an exact measure — with unfortunate consequences for beekeepers, honey producers and consumers.”

Test variations are a source of conflict between beekeepers and honey producers, the paper says, causing differences in payment of up to $2000 for a 300 kg drum of honey.

Manuka Expose´ says AMHA knew of the issue in 2003 when it set up a committee to address the problem.

Five test options were considered, including a minimum inhibitory concentration (MIC) assay developed by a Crop and Food scientist. However, this method was never adopted.

AMHA was made further aware of the test’s limitations in July 2006 when the laboratory it had certified to carry out UMF tests wrote to detail its concerns.

The newspaper quotes New Zealand Laboratory Services Ltd manager Gordana Aleksic admitting a problem with the “repeatability of results” for honeys with high anti-bacterial levels.

The letter also admits NZ Labs has no answer to the problem of partial inhibition, where bacteria in the test are not 100% inhibited. Repeat tests on the same honey alternate between “partial” and “clear”.

Another Manuka Expose´ article reveals AMHA was last year offered methylglyoxal testing as a solution to the problems with UMF tests, but did not reply.

A digital version of Manuka Expose´ is available online at


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