The Difference Between UMF and MGO

Two numbers, two systems

If you read a jar of manuka honey and see "UMF 15+" on one and "MGO 514+" on another, you are not reading the same kind of label. UMF is a certification program. MGO is a chemical assay. The first contains the second, plus three other measurements, plus an external audit.

What MGO tells you

MGO is methylglyoxal in mg/kg, measured by liquid chromatography. It is the single antibacterial compound that does most of the work. An MGO 514+ reading means the assayed sample contained at least 514 mg of methylglyoxal per kilogram. That is a real number from a real instrument. It says nothing about whether the honey was actually manuka, only that there is a lot of MGO in it.

This matters because MGO can be elevated by spiking honey with dihydroxyacetone (DHA), the precursor that converts to MGO over time. Spiking is rare in the major brands but not zero in the bulk market.

What UMF adds

UMF stands for Unique Manuka Factor. It is run by the UMFHA, a New Zealand industry body. To earn a UMF rating, a batch is tested for four markers:

1. MGO (methylglyoxal): the antibacterial.
2. Leptosperin: a marker compound that only appears in genuine manuka nectar. Spiked honey will not have it.
3. DHA (dihydroxyacetone): the precursor. Tracks whether the honey will continue to gain MGO during storage.
4. HMF (hydroxymethylfurfural): a heat and age marker. High HMF means the honey has been cooked or sat too long.

The four are combined into the UMF grade. Crucially, the audit is independent, and the producer pays a license fee for the right to put UMF on the label. That fee, and the audit, are why UMF jars cost more.

So which one matters

For antibacterial activity, only MGO matters in the short term. For authenticity, MGO alone is insufficient because spiking is a known failure mode. UMF is MGO plus three guards against the failure modes.

A simple translation table:

UMF	Approximate MGO
10+	263+
15+	514+
20+	829+

Two jars at "MGO 514+" and "UMF 15+" should contain similar antibacterial activity. But the UMF jar has cleared the leptosperin check; the MGO-only jar has not.

Rule of thumb

On the shelf: if the price gap is small, take the UMF jar. The extra cost buys you three additional assays and an independent audit. If you are choosing between an MGO 514+ at a deep discount and a UMF 15+ at full price, look at the brand. A well-known brand selling MGO-only is almost certainly fine. An unfamiliar brand selling MGO-only with no leptosperin reference is the one to skip.