What MGO Measures and How It Relates to UMF in Manuka Honey

MGO measures the concentration of methylglyoxal in manuka honey, the natural compound most closely tied to its distinctive chemistry, while UMF (Unique Manuka Factor) is the grading system that reports this alongside other markers on a single scale. Together, the two numbers commonly seen on a jar of manuka honey describe overlapping aspects of the same underlying chemical profile.

What MGO Actually Measures

MGO ratings indicate the concentration of methylglyoxal in milligrams per kilogram of honey, and are commonly displayed on packaging as figures such as MGO 100 or MGO 250. The number is a direct chemical measurement — it tells you how much of this compound is present in that specific batch, rather than describing a general category of "manuka" honey.

This measurement matters because of what methylglyoxal appears to do. In laboratory testing, methylglyoxal — the compound identified as manuka honey's main antibacterial component — has shown activity against certain bacteria, including in biofilm form, though this is in-vitro evidence only. That means the activity has been observed in controlled laboratory conditions, against specific bacterial strains, rather than confirmed as a treatment effect in people. Still, it is this in-vitro activity that underpins why methylglyoxal content is treated as a meaningful chemical marker worth measuring and reporting on a label.

Where Methylglyoxal Comes From

Methylglyoxal in manuka honey is understood to form from dihydroxyacetone (DHA), a compound present in manuka flower nectar, with MGO levels changing as the honey matures and is stored. In practical terms, this means a jar's MGO number reflects a chemical process that continues after harvest, rather than a fixed quantity present in the nectar itself. It's part of why testing is typically done close to when honey is packaged rather than relying solely on figures recorded at harvest.

How MGO Relates to UMF

UMF (Unique Manuka Factor) is a grading system used to describe certain natural chemical markers found in manuka honey, including its methylglyoxal content. In other words, UMF is not a separate or competing measurement to MGO — it's a broader, licensed certification that incorporates MGO as one of the markers it tests, alongside leptosperin and dihydroxyacetone (DHA), which help confirm authentic manuka honey.

Manuka honey brands may label products using UMF, MGO, or both systems, and conversion tables published by manufacturers or industry bodies are sometimes used to relate one numbering system to the other. A jar marked UMF 10+ and one marked MGO 263, for example, are often intended to correspond to a similar chemical profile under these conversion tables, even though the two labels describe the measurement in different terms.

The chemistry behind these numbers is well characterised: a recent review of manuka honey research lists methylglyoxal and dihydroxyacetone among its distinctive chemical constituents. The same review notes the field is still refining how grading numbers are standardised and how they relate to health claims, so a grade is best read as a verified measure of what is in the jar.

What the Broader Research Shows

Most of the evidence connecting MGO to real-world outcomes remains at the laboratory stage, but at least one human trial has looked directly at manuka honey consumption in healthy adults. In a small randomized crossover trial of healthy adults, daily consumption of UMF 20+ manuka honey for four weeks did not raise IgE or CML levels and did not measurably alter gut bacterial populations, supporting its safety for healthy individuals at this dose and duration. This is a useful, if limited, data point: it speaks to safety at a specific UMF grade and duration in healthy people, not to any particular outcome tied to MGO content itself, and it doesn't extend to other populations or longer-term use.

Reading MGO and UMF on a Label

Because MGO and DHA levels can change during storage, testing and labelling are typically performed on a specific batch rather than being fixed for the life of the product. Checking for an independent UMF or MGO certification mark on the label can help buyers confirm that a specific batch of honey underwent laboratory testing for these markers. Honey labelled with higher UMF or MGO numbers is generally priced higher than honey with lower ratings, reflecting the higher, rarer chemical concentration being certified.

Understood this way, MGO and UMF aren't rival systems — MGO reports methylglyoxal directly, while UMF folds it into a certification that also checks authenticity markers. Either figure on a label tells you what has actually been measured in the honey you're buying, and a higher number means a higher measured methylglyoxal content.