Manuka Honey: MGO Ratings & the New Zealand Government's Science Definition

Every jar of Manuka Doctor honey is labelled with numbers which show the strength of its MGO content and confirm it is genuine Manuka Honey.

Want to know exactly what it all means? We asked the experts to explain what the numbers stand for and why they are on the label.

Manuka Honey Testing

What does MGO mean in Manuka Honey?

The large number on the front of every jar of Manuka Doctor honey is its MGO rating – which shows the strength of the honey’s antimicrobial activity.

MGO is short for methylglyoxal, the naturally-occurring chemical unique to honey made from nectar gathered from the Mānuka bush. Scientific tests have shown this chemical has antimicrobial properties and the more the honey contains, the greater its bug-fighting power 1.

The MGO scale starts around 30 and goes right up to 840. As a general rule, honey with an MGO rating between 30 and 70 is ideal for daily use, while honey with an MGO rating of between 100 and 240 is better for an extra boost, and anything above 340 is a maximum strength product best for occasional use when you really need it.

How do we know what MGO rating each jar of honey has?

Dr Young Mee Yoon, Chief Technical Officer at Manuka Doctor, explains: “The MGO rating is established through a scientific chemical analysis which looks at three different chemicals present in the honey. The results tell us the activity level of the honey.

Young Mee Manuka Doctor

“We test all our honey to establish its MGO level, first in New Zealand using our own highly technical in-house equipment and then again in an independent laboratory when it arrives in the UK, which means we can guarantee the MGO rating stated on the label is correct and true to label.”

New Zealand Manuka Honey Science Definition

Each jar of Manuka Doctor honey carries labels confirming the honey meets the strict definition of Manuka Honey set by the New Zealand Government and is “Tested Certified Manuka”.

This means each batch has been tested at an independent laboratory for five key markers which prove the honey was made from nectar gathered by bees from the Mānuka bush. The markers are made up of four naturally-occurring chemicals and one DNA marker from Mānuka pollen.

Monofloral or multifloral – and a whole load of numbers!

Our jars also state the honey is either “monofloral” or “multifloral”. This tells you whether the honey is made predominantly from nectar from the Mānuka bush (monofloral) or from a combination of Mānuka and other flowers (multifloral).

Testing Manuka Honey

Independent testing establishes how much of each of the five markers are in each batch of honey – and these results are used to determine whether it is monofloral or multifloral Manuka Honey. Typically, monofloral products contain higher levels of the natural chemicals associated with the Mānuka bush.

What’s the science behind the official definition of monofloral and multifloral New Zealand Manuka Honey?

There are five key markers which identify whether Manuka Honey is monofloral or multifloral. The first four are chemical markers known as phenolic acids. Their full names are called 3-Phenyllactic acid, 2-Methoxyacetophenone, 2-Methoxybenzoic acid and 4-Hydroxypheyllactic acid – so you can see why we can’t fit them on our labels!

Instead, every Manuka Doctor jar displays the minimum levels it contains of each of the chemicals, referred to by their shortened names: 3-PLA, 2-MAP, 2-MBA and 4-HPLA.

For honey to be classed as “monofloral” it has to contain at least 400mg/kg of 3-PLA and 5mg/kg of 2-MAP, as well as at least 1mg/kg of the other two chemicals. “Multifloral” Manuka Honey contains between 20 and 400 mg/kg of 3-PLA and at least 1mg/kg of the other three chemicals.

All honey which is exported from New Zealand as “Mānuka” must also contain a DNA marker from Mānuka pollen, which confirms it has come from the bush. This is why every Manuka Doctor jar also states: “DNA < Cq 36” – this is a scientific way of saying the presence of Mānuka DNA has been confirmed by independent laboratory testing.

How are the tests done?

Only two independent laboratories in New Zealand are approved by the NZ Government to carry out independent testing of these five Mānuka markers.

Jonno Hill is CEO of one the approved labs, Hill Laboratories. He says: “We test for the four chemical markers using a Government-recommended chemical analysis technique called LC-MS (liquid chromatography–mass spectrometry). It’s a highly analytical technique which is expensive but very reliable and wonderfully precise and scientific, so it is free from interferences which could give inaccurate results.

“For the DNA testing we use an analytical technique called quantitative PCR, which is also Government-recommended. We use it for a range of services in the business and it’s a technology which is very well established and there a high degree of confidence in its accuracy.”

70 MGO Manuka Honey

1. Grainger M, Owens A, Manley-Harris M, et al. Kinetics of conversion of dihydroxyacetone to methylglyoxal in New Zealand mānuka honey: Part IV – Formation of HMF. Food Chemistry. 2017;232:648-655.