Manuka honey is a monofloral honey produced by bees that feed on the flowers of the manuka bush (Leptospermum scoparium), a shrub native to New Zealand and parts of Australia. What sets it apart from regular honey is an unusually high concentration of a naturally occurring antibacterial compound called methylglyoxal, or MGO, which gives manuka honey measurable germ-killing properties that other honeys lack. That distinction has turned it into both a regulated medical product and a premium grocery item, with New Zealand exporting over $200 million worth to six major markets in 2021 alone.
Where Manuka Honey Comes From
The manuka bush grows across New Zealand’s North and South Islands, the Chatham Islands, and in the Australian states of New South Wales, Victoria, and Tasmania. It flowers during the Southern Hemisphere’s late autumn and winter, typically May through July, which gives beekeepers a narrow window to place hives near blooming manuka stands. Because the flowering period is short and weather-dependent, production volumes fluctuate from year to year, and genuine monofloral manuka honey remains relatively scarce compared to global demand.
What Makes It Different From Regular Honey
All honey has mild antibacterial properties, mostly from hydrogen peroxide that forms when an enzyme in bee saliva reacts with glucose. Manuka honey has that too, but its real distinction is methylglyoxal. MGO forms naturally inside the honey from a precursor sugar called dihydroxyacetone (DHA) found in manuka nectar. Over time, DHA converts to MGO, and the final concentration can be dozens of times higher than in conventional honeys.
MGO attacks bacteria in several ways. It can alter the shape and size of bacterial cells by disrupting the internal ring that controls cell division, essentially forcing cells to divide prematurely or incompletely. In lab studies, bacteria exposed to even low concentrations of manuka honey produced smaller, misshapen cells with condensed genetic material. Perhaps most notably, research on MRSA (methicillin-resistant Staphylococcus aureus) has shown that manuka honey can down-regulate specific resistance genes, potentially reversing antibiotic resistance in these difficult-to-treat bacteria.
How the Grading System Works
If you’ve shopped for manuka honey, you’ve seen numbers like UMF 10+ or MGO 250+ on the label. These aren’t arbitrary marketing terms. The UMF (Unique Manuka Factor) system is managed by New Zealand’s UMF Honey Association and tests for four chemical markers. Each UMF grade corresponds to a minimum MGO concentration:
- UMF 5+: at least 83 mg/kg of MGO
- UMF 10+: at least 261 mg/kg
- UMF 15+: at least 512 mg/kg
- UMF 20+: at least 826 mg/kg
- UMF 25+: at least 1,197 mg/kg
Higher numbers mean more antibacterial activity and, predictably, a higher price. For general wellness use like adding to tea or toast, UMF 5+ or 10+ is typical. People buying manuka honey specifically for its antibacterial properties tend to look for UMF 15+ and above. Some brands skip the UMF system entirely and just list the MGO concentration directly, which gives you the same information.
How New Zealand Regulates Authenticity
Fraud is a real problem in the manuka honey market. By some estimates, more “manuka honey” is sold worldwide than New Zealand actually produces. To combat this, New Zealand’s Ministry for Primary Industries requires every jar of exported manuka honey to pass two tests before it can legally be called monofloral manuka.
The first is a chemical test. The honey must contain specific levels of four marker compounds, including at least 400 mg/kg of 3-phenyllactic acid and at least 5 mg/kg of 2′-methoxyacetophenone. The second is a DNA test confirming the presence of manuka pollen at a threshold concentration. Both tests must be passed for the honey to carry the monofloral manuka label.
Scientists have also identified a compound called leptosperin as a promising authenticity marker. Unlike MGO (which changes over time as DHA converts), leptosperin is heat-stable and remains chemically intact during prolonged storage. It produces a unique fluorescence signature found only in honey from the Leptospermum genus, making it very difficult to fake. Leptosperin doesn’t appear naturally in clover, acacia, or other common honeys.
Medical Uses for Wound Care
Manuka honey isn’t just a pantry item. Medical-grade versions are used in hospitals. The FDA has cleared manuka-based wound dressings, such as the Medihoney line, for clinical use. These products contain 80% active manuka honey blended with thickening agents that help the gel stay in contact with the wound.
For over-the-counter use, these dressings are intended for minor cuts, abrasions, small burns, and lacerations. Under the supervision of a healthcare professional, they’re also used on more serious wounds: diabetic foot ulcers, venous leg ulcers, pressure sores, first- and second-degree burns, and surgical wound sites. The honey creates a moist healing environment while its antibacterial activity helps keep the wound clean. This is not folk medicine. It is a regulated, FDA-cleared medical device.
Digestive and Other Proposed Benefits
Many people take a spoonful of manuka honey for sore throats or digestive discomfort, and there is some scientific basis for this. Lab studies have shown that manuka honey inhibits the growth of Helicobacter pylori, the bacterium responsible for most stomach ulcers. Multiple honey samples in research produced growth inhibition even at significant dilutions. However, it’s worth noting that most of this evidence comes from laboratory studies rather than large clinical trials, so the effective “dose” for gut health in humans hasn’t been firmly established.
Manuka honey also has a lower pH than many other honeys and contains anti-inflammatory compounds, which may help soothe irritated throat tissue. Its thick consistency coats the throat more effectively than thinner liquids, providing a physical barrier that may reduce irritation.
What to Look for When Buying
The single most important thing on the label is a verified grading number, either UMF or MGO. A jar labeled simply “manuka honey” without a grading number could be a blend with very little actual manuka content. Look for the UMF trademark (a black fern logo) or a clearly stated MGO concentration from a brand that provides third-party test results.
Price is also a useful signal. Genuine UMF 15+ manuka honey typically costs $40 to $80 or more for a 250g jar. If you find a large jar of “manuka honey” for $15 at a discount store, it is almost certainly not monofloral manuka, or the MGO content is negligible. New Zealand-sourced honey that meets MPI export standards is the safest bet for authenticity, since those jars have passed both chemical and DNA testing before leaving the country.
Store manuka honey at room temperature, away from direct sunlight. Its antibacterial compounds are relatively stable over time, but excessive heat can degrade some of the beneficial markers. There is no need to refrigerate it.