Manuka honey jars come covered in numbers: UMF 10+, MGO 250+, sometimes both. Those numbers mean something, but not always what shoppers assume. Here's a plain-English guide.
Written by Vita Globe Editorial Team | Reviewed against the UMF Honey Association and peer-reviewed research
What do UMF and MGO mean on manuka honey?
MGO is methylglyoxal, the compound identified as the main source of manuka honey's antibacterial activity, reported in mg per kg[1][2]. UMF (Unique Mānuka Factor) is a certified grading system that tests MGO plus other markers for authenticity and freshness; for example, UMF 10+ corresponds to at least 261 mg/kg MGO[3].
Caveat: These are quality and potency markers for the honey. A higher number isn't proof of a bigger health benefit when you eat it.
Sources: Mavric et al. 2008 · Adams et al. 2008 · UMF Honey Association · Verified 2026-09-27
In this article
What is manuka honey?
Manuka honey is made by bees that feed on the flowers of the manuka plant (Leptospermum scoparium), native to New Zealand. It tends to be darker, thicker and more earthy-tasting than typical clover honey, and it costs a lot more.
The price comes down to chemistry. In 2008, two research groups independently reported that methylglyoxal (MGO) is responsible for much of manuka honey's unusual antibacterial activity in lab tests[1][2]. That finding is why MGO shows up on so many labels today.
What does MGO mean?
MGO stands for methylglyoxal. On a label, it's usually written as a number such as MGO 100+ or MGO 250+, which refers to milligrams of methylglyoxal per kilogram of honey.
Researchers found that manuka honeys contain much higher MGO levels than other honeys, and that MGO was the dominant antibacterial constituent they measured[2]. The UMF Honey Association notes that another compound in manuka honey, dihydroxyacetone (DHA), converts to MGO over time[3]. That's why a manuka honey's MGO level can keep changing after harvest.
What does UMF mean?
UMF stands for Unique Mānuka Factor. It's a certified trademark run by the UMF Honey Association in New Zealand. Instead of measuring only MGO, UMF grading tests several markers[3]:
- MGO — the potency marker.
- Leptosperin — an authenticity marker linked to manuka nectar.
- DHA — which converts to MGO over time, so it helps predict shelf life.
- HMF — a freshness marker used to check the honey hasn't been overheated.
According to the UMF Honey Association, honey carrying the UMF mark must pass its grading tests, with independent testing to confirm the label[3].
How do UMF and MGO compare?
The UMF Honey Association publishes the minimum MGO level for each UMF grade[3]:
| UMF grade | MGO (mg/kg) |
|---|---|
| UMF 5+ | 83 |
| UMF 10+ | 261 |
| UMF 15+ | 512 |
| UMF 20+ | 826 |
| UMF 25+ | 1,197 |
One thing to know: the association says an MGO number alone can't be converted into a full UMF rating, because UMF also covers authenticity and freshness markers[3]. An MGO-only label tells you potency, not the whole story.
Does a higher number mean more health benefits?
Not necessarily. MGO's antibacterial effects were measured in the lab[2], which is different from what happens when you eat honey. The best-studied everyday use of honey, for cough symptoms, mostly involved ordinary honey rather than graded manuka[4]. There's no strong evidence that a UMF 20+ jar eases a cough better than a supermarket honey. We cover that research in Honey for Sore Throats and Coughs: What Research Shows.
What every honey has in common: it's a sugar, which counts toward added-sugar limits[6], and it's never safe for babies under 12 months[5]. More in Is Manuka Honey OK for Kids?.
The honest summary
- MGO measures methylglyoxal, manuka's main antibacterial compound in lab tests.
- UMF is a certified grade that checks MGO plus authenticity and freshness markers.
- Higher grades mean higher MGO, not proven extra benefits when eaten.
- Any honey is still sugar and still off-limits for babies under 1.
Our option
Vita Globe Vitalolli™ Manuka Honey Lollipops
A slow-dissolving honey treat made with genuine Manuka honey from New Zealand. It's not a dietary supplement, has no added vitamins, and we don't list a UMF or MGO grade for it, so we make no potency or health claims. Recommended for ages 4 and up; never for babies under 12 months.
Frequently asked questions
Is UMF or MGO better?
UMF is broader: it includes MGO plus authenticity and freshness markers, and it's independently certified[3]. MGO alone tells you methylglyoxal content only.
What UMF is best for everyday eating?
For eating on toast or in tea, a lower grade is fine. Higher grades have more MGO[3], but there's no strong evidence that eating a higher grade brings more benefit.
Does heating manuka honey destroy MGO?
Heat can change honey's chemistry, and UMF uses HMF as a marker of overheating[3]. If potency matters to you, avoid boiling it.
Is manuka honey safe for babies?
No. No honey of any kind should be given to a child under 1 year old[5].
Sources
- Adams CJ, Boult CH, Deadman BJ, Farr JM, Grainger MNC, Manley-Harris M, Snow MJ. Isolation by HPLC and characterisation of the bioactive fraction of New Zealand manuka (Leptospermum scoparium) honey. Carbohydrate Research. 2008;343(4):651-659. doi:10.1016/j.carres.2007.12.011
- Mavric E, Wittmann S, Barth G, Henle T. Identification and quantification of methylglyoxal as the dominant antibacterial constituent of Manuka honeys from New Zealand. Molecular Nutrition & Food Research. 2008;52(4):483-489. doi:10.1002/mnfr.200700282
- UMF Honey Association. Unique Mānuka Factor (UMF) Grading System Explained. umf.org.nz
- Abuelgasim H, Albury C, Lee J. Effectiveness of honey for symptomatic relief in upper respiratory tract infections: a systematic review and meta-analysis. BMJ Evidence-Based Medicine. 2021;26(2):57-64. doi:10.1136/bmjebm-2020-111336
- Centers for Disease Control and Prevention. Botulism Prevention. CDC.gov. cdc.gov/botulism/prevention
- Centers for Disease Control and Prevention. Get the Facts: Added Sugars. CDC.gov (last reviewed April 2026). cdc.gov
About the Vita Globe Editorial Team
The Vita Globe Editorial Team researches and writes our wellness content, working from peer-reviewed research, systematic reviews and guidance from bodies such as the NIH and the FDA. We cite our sources inline and update articles when the evidence changes.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational purposes only and is not a substitute for medical advice. Talk to your healthcare provider before starting any new supplement, particularly if you are pregnant, nursing, taking medication, or caring for a child.
