Scientists thought one compound made mānuka honey a germ killer. Turns out the bees have been running a whole chemistry lab, and nobody asked to see the notes.

For years, the story of mānuka honey was simple. It kills bacteria because it's loaded with a chemical called methylglyoxal, or MGO. End of story. Buy the expensive jar with the big number on it.

New research from Aston University in the UK says that story was missing a few chapters.

Working with scientists at Comvita, a New Zealand honey producer, a team led by Dr. Jonathan Cox tested mānuka honey against some genuinely nasty bacteria. Their conclusion, published in the journal Microbiology: MGO is only part of what makes this honey punch above its weight. Something else in the jar is helping, and right now nobody knows exactly what.

First, why anyone cares about honey in 2026

Antibiotics are losing. Not everywhere, and not all at once, but bacteria keep learning to shrug them off. Public health officials call it antimicrobial resistance, or AMR. Most people call it "superbugs," which is a much better name and also more terrifying.

The problem with most antibiotics is that they work like a sniper. One drug, one target. Bacteria only need one lucky mutation to make that target disappear, and suddenly the drug is a very expensive sugar pill.

Honey doesn't work like a sniper. It works like a bar fight. There are several things going wrong for the bacteria at once, which makes it much harder for them to adapt. That's a big part of why researchers keep circling back to it.

What makes mānuka honey different

All honey has some germ-fighting ability. It's basically a supersaturated sugar syrup, which sucks the water out of bacteria like a chemical Shop-Vac. It's acidic. And bees add an enzyme that slowly produces hydrogen peroxide, the same stuff in the brown bottle in your bathroom.

Mānuka honey brings something extra. Bees make it from the nectar of a New Zealand shrub called Leptospermum scoparium. That nectar contains a compound that slowly converts into MGO as the honey sits. Most honeys have barely a trace. Mānuka can have a mountain of it.

But MGO has never been the only thing in the jar. Mānuka honey also contains phenolic acids, flavonoids, leptosperin, methylsyringate, leptosin, various enzymes, and an antimicrobial peptide called bee defensin-1, which sounds like a superhero sidekick and, in fairness, kind of is. Many of these have shown germ-fighting activity on their own.

There was also a clue sitting in the research literature since 2011. When scientists chemically neutralized the MGO in mānuka honey, the honey still killed bacteria. Something else was doing work. Nobody had pinned down what.

The experiment, explained without the jargon

You've probably seen "UMF 10+" or "UMF 20+" on a jar. UMF stands for Unique Mānuka Factor, a New Zealand certification tied to how much MGO the honey contains. Bigger number, more MGO, bigger price tag.

The Aston team tested five grades: 5+, 10+, 12+, 15+, and 20+.

They pitted each one against four bacteria that cause serious lung and wound infections:

• MSSA, ordinary staph

• MRSA, the drug-resistant version of staph that hospitals lose sleep over

• Klebsiella pneumoniae, a frequent cause of hospital-acquired pneumonia

• Pseudomonas aeruginosa, an opportunist that's famously hard to kill

Then came the clever part. The researchers didn't just test honey against nothing. They built two fake honeys as controls.

Fake honey #1 matched the real honey's sugar content exactly, minus everything else. Just syrup.

Fake honey #2 matched the real honey's MGO content exactly, minus everything else.

If sugar explained the effect, fake honey #1 should have performed just as well. If MGO explained the effect, fake honey #2 should have. This is the scientific equivalent of a lineup, and it's the reason the study matters.

What they found

Higher grade, stronger effect. Every honey slowed bacterial growth, and the higher UMF grades needed less honey to do it.

Staph got wrecked. The others held up better. MSSA and MRSA folded at lower concentrations. Klebsiella and Pseudomonas needed more. This tracks with earlier research. Those two bacteria are what scientists call Gram-negative, meaning they wear an extra outer membrane over their cell wall. Picture armor with a raincoat on top.

Sugar lost. Real honey beat the sugar-matched fake every time. So no, you cannot replicate this with maple syrup, and please stop asking.

MGO lost too. The MGO-matched fake did kill bacteria, credit where it's due, but the real honey generally did better. Something in the whole honey is adding to the effect.

The part where we pump the brakes

Science reporting has a bad habit of turning "interesting lab result" into "MIRACLE CURE FOUND IN GRANDMA'S PANTRY." So, some honesty:

This happened in a lab, not a person. These were bacteria in plastic trays. A human body is considerably more complicated than a plastic tray.

"Better together" doesn't automatically mean "synergy." That word gets thrown around a lot. A 2022 study found that MGO and the rest of the honey mostly just add up rather than multiplying each other's power. The Aston results show the non-MGO stuff clearly matters. Exactly how it matters is still an open question.

Nobody knows which compounds are doing it. That's literally the next phase of the research.

Do not swap your antibiotics for a spoonful of honey. If a doctor prescribed antibiotics, take the antibiotics. Skipping them is one of the things that created this mess in the first place.

Do not put grocery store honey in an open wound. Medical honey products are sterilized and regulated. The jar in your cupboard is not.

Never give honey to a baby under 12 months. Honey can contain bacterial spores that a baby's gut can't handle yet. This causes infant botulism, which is serious. This rule has nothing to do with mānuka specifically and everything to do with all honey.

What happens next

Cox's team is still working with Comvita to hunt down the mystery compounds and figure out how they interact. If they succeed, the payoff isn't a fancier jar of honey. It's the possibility of new honey-derived medicines built around whatever combination turns out to work.

"Mānuka honey is often viewed through the lens of a single compound, methylglyoxal, but our findings show that the story is far more complex," Cox said. "High-grade mānuka honey appears to derive its antimicrobial activity from a combination of factors working together, and understanding those interactions could help unlock new approaches to tackling infection in an era of increasing antimicrobial resistance. It turns out, the very nature of mānuka honey, in all its complexity, may hold a powerful solution to the emerging global AMR crisis. We just need to learn how best to use it."

Dr. Jackie Evans, Comvita's chief science officer, added that MGO "is only part of the story," and called the work early stage while noting it points to the importance of the honey's other bioactive compounds.

Bottom line: bees have been formulating a complicated antibacterial cocktail for millions of years without a grant application, a lab coat, or a single peer reviewer. Humans are only now sitting down to read the recipe.

REFERENCES
Allcott, G. J., Evans, J., Merry, T. L., & Cox, J. A. G. (2026). Unique Mānuka Factor (UMF)-dependent antimicrobial activity of Mānuka honey against respiratory pathogens cannot be explained by sugar and methylglyoxal alone. Microbiology. https://doi.org/10.1099/mic.0.001746