Manuka honey is made from the nectar of the manuka bush (Leptospermum scoparium), a plant native to New Zealand. Like all honey, it’s primarily sugar and water, with fructose making up about 34% and glucose about 28%. What sets manuka honey apart is a compound called methylglyoxal, or MGO, which forms naturally as the honey matures and gives it unusually strong antibacterial properties.
The Sugar and Water Base
At its core, manuka honey has the same foundation as any other honey. Fructose is the dominant sugar at roughly 34%, followed by glucose at about 28%. Moisture content sits around 12%, which is on the lower end for honey and contributes to its thick, almost creamy texture. These three components alone account for roughly three-quarters of what’s in the jar.
The remaining fraction is where manuka honey diverges sharply from clover, wildflower, or any other variety you’d find on a grocery shelf.
Methylglyoxal: The Defining Compound
The compound that makes manuka honey genuinely different is methylglyoxal (MGO). Most honeys contain trace amounts. Manuka honey typically contains 40 to 800 mg/kg, and some high-grade batches reach up to 1,900 mg/kg. MGO is directly responsible for manuka honey’s potent antibacterial activity.
MGO doesn’t come from the bees. It forms during honey maturation through a slow, irreversible chemical reaction. The manuka bush produces a sugar called dihydroxyacetone (DHA) in its nectar. DHA is present in the fresh nectar and in young honey, but over weeks and months it converts into MGO without any enzymes driving the process. The longer the honey matures, the more DHA converts, and the higher the MGO concentration climbs.
This is why the age and storage conditions of manuka honey matter. A freshly harvested batch will have lower MGO levels than the same honey tested months later, because the conversion is still happening.
Enzymes and Hydrogen Peroxide
All honey contains an enzyme called glucose oxidase, which bees produce in their glands and add to nectar as a natural sterilizer. This enzyme converts glucose into hydrogen peroxide, one of the main reasons regular honey has mild antiseptic properties.
Manuka honey has an interesting quirk here. Its high MGO concentration actually interferes with glucose oxidase activity by altering the enzyme’s structure. So while most honeys rely on hydrogen peroxide for their antibacterial effects, manuka honey relies primarily on MGO instead. This distinction matters because hydrogen peroxide breaks down easily when exposed to heat or bodily fluids, while MGO is more stable.
Phenolic Compounds and Flavonoids
Beyond MGO, manuka honey contains a distinctive profile of plant-derived antioxidants. The major flavonoids include pinobanksin, pinocembrin, and chrysin, with smaller amounts of quercetin, kaempferol, and galangin. On the phenolic acid side, researchers have identified compounds including syringic acid, benzoic acid, kojic acid, and phenyllactic acid.
One compound in particular, called leptosperin, is unique to honey made from Leptospermum species. Leptosperin is a sugar-linked molecule derived from the nectar itself, and it produces a distinctive fluorescence signature that scientists can use to verify whether honey genuinely comes from manuka flowers. Unlike DHA and MGO, leptosperin is heat-stable, making it a more reliable marker for authenticity testing.
Amino Acids and Trace Components
Manuka honey contains roughly 30 to 50 mg/kg of amino acids, sourced both from the plant nectar and from the bees themselves. The most abundant is proline, which comes primarily from bee secretions rather than the flower. Researchers have identified at least 21 distinct amino acids in manuka honey using advanced separation techniques. These are present in small quantities but contribute to the honey’s overall nutritional complexity and its characteristic flavor.
How Grading Reflects Composition
When you see numbers on a manuka honey label, they’re telling you about the concentration of these bioactive compounds. The two most common systems are MGO (measured in mg/kg) and UMF (Unique Manuka Factor), which is a broader grading that accounts for MGO, leptosperin, and DHA together.
The two scales roughly correspond to each other:
- UMF 5+ equals about 83 mg/kg MGO
- UMF 10+ equals about 263 mg/kg MGO
- UMF 15+ equals about 514 mg/kg MGO
- UMF 20+ equals about 829 mg/kg MGO
Higher numbers mean more MGO and stronger antibacterial activity. For general use, a UMF 10+ or MGO 263+ is often considered the threshold where meaningful bioactivity begins. The most potent (and most expensive) grades, UMF 20+ and above, contain MGO levels exceeding 800 mg/kg.
How Authenticity Is Verified
Because manuka honey commands premium prices, authentication is a real concern. Genuine monofloral manuka honey must contain at least 70% manuka pollen grains when examined under a microscope. This high threshold exists because manuka pollen is considered “over-representative,” meaning bees collect a disproportionate amount of it relative to how much nectar they gather from the plant.
Chemical testing adds another layer. Leptosperin, the fluorescent compound unique to Leptospermum honeys, can be detected through spectroscopy and serves as a rapid screening tool. Combined with MGO and DHA measurements, these markers create a chemical fingerprint that distinguishes real manuka honey from blends or mislabeled products. If you’re buying manuka honey and want to ensure you’re getting what you pay for, look for a jar with either a UMF or MGO rating from a certified testing body rather than vague claims about being “manuka style” or “manuka blend.”