MGO in Manuka honey stands for Methylglyoxal, a naturally occurring chemical compound attributed to the antibacterial properties for which Manuka honey is so well-known.
All honey has some naturally occurring antibacterial qualities, called peroxide activity. Manuka Honey has additional antimicrobial activity, above and beyond what is present other raw honey types. This additional antimicrobial activity is what scientists call ‘non-peroxide activity’.
For many years, the cause of this ‘non-peroxide activity’ in Manuka Honey wasn’t well understood. So the term ‘Unique Manuka Factor’ (UMF®) was adopted to measure the strength of Manuka Honey.
In 2006, scientists in Germany published research showing that Manuka honey’s ‘non-peroxide’ antimicrobial activity was closely related to the presence of the compound methylglyoxal. The relationship between methylglyoxal levels and ‘non-peroxide activity’ in New Zealand manuka honey was further demonstrated by researchers at Waikato University in a paper published in 2008. 
What is Methylglyoxal?
Methylglyoxal (MGO) is an organic compound which, in organisms, is formed as a side-product of several metabolic pathways. Methylglyoxal mainly arises as side products of glycolysis involving glyceraldehyde-3-phosphate and dihydroxyacetone phosphate. 
Methylglyoxal in Manuka honey originates from the dihydroxyacetone present in the nectar of Manuka flowers. 
Why is MGO in Manuka Honey Important?
Manuka honey is unique to other kinds of raw honey because of its high quantities of methylglyoxal (MGO). The concentration of MG in Manuka honey is up to 100-fold higher than in conventional honey . It is the high level of MGO that makes Manuka honey beneficial as an antimicrobial and anti-inflammatory agent.
Not all Manuka honey is created equally. Manuka honey has varying quantities of MGO, depending on the source of the pollen collected from Manuka trees and how much the bees collected other types of pollen at the same time (diluting the Manuka honey). For this reason, it’s important to consider the MGO factor when you are buying Manuka Honey. Manuka with a higher MGO is more expensive because it is more scarce and in high demand.
At Forest Maker Honey, we have the following MGO levels of 100+, 250+ and 550+, available in different sized jars.
MGO and UMF, what’s the distinction?
UMF stands for Unique Manuka Factor. Whereas the MGO measure only takes into consideration the quantity of methylglyoxal in the honey, UMF takes into account other unique factors of manuka honey. Which includes Leptosperin and DHA, as well as Methylglyoxal.
The chart below, sourced from the Unique Manuka Factor Honey Association show’s the UMF rating on the y-axis and the corresponding measurement of Leptosperin, DHA, and Methylglyoxal in milligrams per 1kg on the x-axis. This diagram gives an idea of the variation in the scale of the MGO factor and the UMF factor.
To be considered potent enough to be therapeutic, Manuka honey needs a minimum rating of 10 UMF. Honey at or above that level is marketed as “UMF Manuka Honey” or “Active Manuka Honey.” A UMF factor of 10 has a minimum MGO rating of 263, which means the honey has 263mg of MGO per 1kg.
MGO is an important contributor to the Manuka honey industry as a measure for consumers, producers and researchers to consider Manuka honey.
MGO measures the amount of Methylglyoxal present in the honey, which is what most of the unique benefits of Manuka honey are attributed to, based on current research.
Before you purchase Manuka honey, check MGO grade to make sure you’re buying the level that suits your needs.