Manuka Honey Terroir: How Place Affects MGO
Where manuka grows affects how much dihydroxyacetone (DHA) its nectar carries, and DHA is the precursor of the methylglyoxal (MGO) that labels report. Research shows large differences between regions, between years and even between neighboring trees. This page covers what is known, what is still unclear, and what it means when you read a label.
What You'll Learn
You will learn where MGO comes from, what a 2014 study found about nectar DHA across regions, years and individual trees, how DHA turns into MGO during storage, and why the number on the label is a better guide to potency than a region name.
The Terroir Foundation: Where Chemistry Meets Geography
MGO is not made directly by the bees or the bush. Manuka nectar contains dihydroxyacetone, and during storage the DHA in the honey converts to methylglyoxal (Adams et al. 2009). So how much MGO a batch can reach depends partly on how much DHA the nectar carried.
Site to Site
Nectar DHA differs between regions. Researchers have not tied that difference to one soil factor, and DHA also varies from tree to tree on the same site.
Year to Year
The same region can shift between seasons. In a comparison of 2009 and 2010, East Cape nectar moved from a low DHA class to a moderate one.
Tree to Tree
Trees within 50 to 100 meters of each other ranged from low to high DHA at study sites in Coromandel and East Cape.
A study in the Journal of Agricultural and Food Chemistry measured manuka nectar across New Zealand (Williams et al. 2014). It found differences between regions, between years and between individual trees, and the authors reported that variation within a single tree was the largest source. Nectar DHA also does not always match the MGO in the finished honey, because storage conditions affect the conversion.
What Is Not Established
Soil Is Not a Proven Dial
Some sites claim that a specific soil pH or mineral level produces higher MGO. We have not found a published study that sets such thresholds for manuka, so we do not state one. Soil, climate, plant genetics and weather all play a part, and researchers are still sorting them out.
Mineral content in honey does vary by origin, and laboratories use it alongside other markers to check where a honey came from. That is different from showing that a mineral raises MGO or improves healing, and nothing on this page claims it does.
Honey carries trace elements that come from the soil and the plant. They can help with origin testing. We are not aware of clinical trial evidence that ties a particular trace element in manuka honey to wound outcomes.
Origin Testing Helps Spot Fraud
Laboratories combine several tests, such as marker compounds and trace element profiles, to check that a honey is what the label says. No single test settles it, and fraud still happens. That is why grading schemes such as UMF look at more than one marker.
What the Regional Data Shows
In the Williams et al. study, most regional averages were below the levels seen in planted cultivars. Coromandel and Wairarapa were similar to each other, and East Cape was lower than both in 2009 and 2010. Only Nelson came close to cultivar levels in 2009.
That does not rank regions by honey potency. The study measured nectar, not jars of honey, and a region name on a label does not guarantee an MGO level. To compare jars, use the MGO or UMF number. Our MGO and UMF guide explains how.
From Nectar to Numbers: The DHA to MGO Conversion
DHA does not become MGO right away. Freshly made manuka honey has little MGO and a lot of DHA. During storage, DHA falls and MGO rises (Adams et al. 2009). Storage temperature affects the rate, so producers control it, and the result varies from batch to batch.
Fresh Harvest
Mostly DHA and little MGO. Freshly made honey can test low for MGO even when the nectar was rich in DHA.
Maturation Phase
Over weeks to months of storage, DHA converts to MGO without enzymes. Temperature and honey composition affect how fast.
Finished Honey
MGO rises as DHA falls. Producers test the finished honey and label it with the measured MGO, so the label, not the region, tells you the result.
Phenolic Compounds and the Wound Healing Matrix
MGO gets most of the attention, but manuka honey also contains phenolic compounds and other markers. Some are used to confirm that a honey is genuine manuka. Their role in wound healing in people has not been established.
A phenolic compound found in many honeys. Lab studies describe antioxidant activity. Whether it matters for wounds in people is not established.
Another phenolic compound found in honey. Lab work describes antioxidant activity. Its effect in wounds has not been shown in trials.
A marker compound found in manuka honey. Laboratories measure it to help confirm that a honey is genuine manuka.
Not Just MGO
MGO is one of several factors that lab studies point to in manuka honey's antibacterial activity, alongside the honey's sugar content and acidity. Claims that phenolics work with MGO to heal wounds, or that natural honey beats synthetic MGO in trials, are not supported by the studies we reviewed. Our biofilm research page shows what the evidence does say.
Authentication Through Geographical Fingerprinting
An MGO test tells you how much methylglyoxal is in a jar. Other tests help check that the honey is genuine manuka and not diluted or blended. Reputable brands provide lab results, and a licensed UMF grade includes several of these checks.
Isotope Analysis
Carbon isotope tests are a standard way to detect added cane or corn sugar in honey.
Mineral Profiling
Trace element profiles can help show a honey's likely origin. Labs use them next to other markers, since no single test is conclusive.
Why Fraud Prevention Matters
Manuka honey sells at a premium, and mislabeled or diluted honey has been found on the market. Testing for several markers makes this harder but does not remove the risk. Buy from brands that show a stated MGO or UMF number and a batch or license reference.
What to Ask a Seller
Whether you are a shopper or a clinic buyer, ask what the label number is based on. A certificate of analysis (COA) from the supplier shows the tested MGO and the test date.
Ask for the tested MGO value and the test date. Some suppliers also provide leptosperin and other marker results.
Suppliers that can name where a batch was harvested make claims easier to check. A region name alone does not tell you the MGO.
Honey from a food jar is not sterile and is not a wound dressing. For wounds, use products made and regulated for that purpose. See Clinical Wound Gels.
Key Points
MGO in manuka honey comes from DHA in the nectar. Nectar DHA varies between regions, years and individual trees, and DHA converts to MGO during storage.
No soil or region has been shown to guarantee a given MGO level. Potency is established by testing the finished honey, and marker tests help check that it is genuine.
Use the label's MGO or UMF number to compare jars, and use medical-grade products for wounds.
Sources
- Adams CJ, Manley-Harris M, Molan PC. The origin of methylglyoxal in New Zealand manuka (Leptospermum scoparium) honey. Carbohydrate Research. 2009;344(8):1050-1053. PubMed
- Williams S, King J, Revell M, et al. Regional, annual, and individual variations in the dihydroxyacetone content of the nectar of manuka (Leptospermum scoparium) in New Zealand. Journal of Agricultural and Food Chemistry. 2014;62:10332-10340. Full text
Continue Exploring the Science
Terroir explains where potency originates, but the full clinical picture requires understanding MGO's antibacterial mechanism, the certification standards that verify it, and the treatment protocols that apply it. These three resources connect the dots from soil chemistry to wound care.