Mānuka Honey, MGO and heat – the full facts

A recent newspaper article here in the UK quoted a Professor from New Zealand who said that Mānuka Honey can be affected by heat.


There is a lot of misinformation about this topic so we spoke to our Research Team based over in Hamilton, in the North Island of New Zealand, for the full facts on this story.

Here's what they said:

"First of all, the story refers to the ingredient MGO, which is found in Mānuka Honey. The report claims that the level of MGO can go down after exposure to extreme heat and sunlight.

MGO stands for methylglyoxal and is the active element in Mānuka Honey which scientists generally concur is linked to its anti-microbial effect.

Because MGO is a naturally occurring compound it's true it can be affected by things like heat, but also soil type, moisture, or the location of the manuka bush where it was harvested.

That's why we test the MGO level twice. Once in New Zealand where our honey is harvested and packed. Then again in the UK at Fera Science, an independent lab, before we put them on sale on our website.

This means that we can be sure that the MGO level on the label is the same as the honey inside.

In the story published in The Times newspaper, Professor Manley-Harris said that MGO can be affected by "prolonged exposure" to heat, commenting:

"A day in the sunshine won’t make a difference, but a few weeks in a hot shop window would. Short term exposure to heat – such as putting a spoonful of honey in tea – will not harm its effectiveness."

Our advice is to keep your Mānuka Honey in a cool, dry place. A kitchen cupboard is perfect.