Researchers at Aston University in England have found that the antibacterial punch of manuka honey rests on several bioactive compounds working together, not just its sugar content and a single molecule called methylglyoxal (MGO). The finding, published in the journal Microbiology in August 2026, unsettles the way this premium honey has been graded and marketed for years.
For US shoppers, the practical question is what that means for a product that routinely sells for many times the price of ordinary honey. Many jars are sold on the strength of a bold MGO number printed on the label, with higher numbers commanding higher prices.
What the study actually tested
Working in partnership with the New Zealand producer Comvita, the team tested manuka honeys spanning Unique Manuka Factor (UMF) ratings from 5+ through 20+, and antibacterial activity rose in step with the UMF grade.
To see whether MGO and sugar could account for that effect, the researchers built lab formulations matching the same MGO and sugar concentrations. Those synthetic mixtures were then pitted against bacteria that cause respiratory infections, and they fell short of what the real honey did.
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Dr. Jonathan Cox, senior lecturer in biosciences at Aston University who led the work, said in a statement that "mānuka honey is often viewed through the lens of a single compound, methylglyoxal, but our findings show that the story is far more complex."
The gap points to other bioactive compounds, or interactions between compounds, that the sugar and MGO alone cannot explain. The team is now working to identify them.
What UMF and MGO actually measure
The two numbers you see on manuka labels are not the same thing. MGO is a straight readout of methylglyoxal in milligrams per kilogram. UMF is a broader certification developed in New Zealand that checks four markers: MGO for potency, leptosperin as an authenticity marker unique to manuka, DHA as a shelf-life indicator, and HMF to flag honey that has been overheated or stored too long.
That difference matters here. The Aston findings sit alongside UMF's own broader framing, that the honey's quality is a fingerprint of several compounds rather than one molecule. What is new is direct laboratory evidence that MGO by itself cannot reproduce the antibacterial effect.
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Why researchers keep looking at manuka
Antibiotic resistance is one of the largest health threats worldwide. Bacterial antimicrobial resistance was associated with more than 4.7 million deaths globally in 2021, according to the World Health Organization.
That is why manuka keeps drawing scientific attention. Cox called the honey, in all its complexity, "a powerful solution to the emerging global AMR crisis."
For shoppers, the practical takeaway is smaller. Higher-graded honeys still showed stronger antimicrobial activity in the lab, so the grade is not meaningless. But readers who assume a bigger MGO number is the only thing they are paying for may be paying for a partial picture.
Anyone considering manuka honey to help manage a wound or a stubborn infection should talk to a doctor first. Honey is not a substitute for prescribed treatment.
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