Solid cheddar is good for the gut — but melt it and the benefits largely disappear
Heating cheddar disrupts its structure and reduces the microbiome benefits it offers in its solid state
Cheese on toast may be the nation's most beloved snack, but new research suggests it could be doing the gut more harm than good — at least compared with eating cheddar in its unmelted form.
What the research found
Scientists discovered that consuming solid cheddar had a positive effect on the gut microbiome — the complex community of bacteria and other organisms in the intestines, thought to influence everything from mood to immune function.
Unmelted cheddar increased the diversity of these microorganisms, which is a key marker of a healthy gut.
When the same cheese was melted, however, that diversity was reduced, with researchers concluding the gut health benefits were largely cancelled out.
How the study was conducted
Researchers from University College Dublin designed the experiment to measure how cheddar affects this delicate internal balance.
They tracked 69 volunteers over six weeks: some ate 120g of unmelted cheese each day, whilst others consumed the same quantity in melted form. At the close of the trial, the team assessed changes in participants' gut bacteria.
Their findings confirmed that cheddar is broadly beneficial for the microbiome — but that applying heat, as one would when making cheese on toast, significantly diminishes those advantages.
Heating hard cheese damages its structure, the scientists explained, making it more difficult for the body to absorb the beneficial nutrients it contains.
The science behind it
The study, published in Frontiers in Microbiology, set out the mechanism in detail. The researchers wrote: "When cheddar cheese is melted, the dense semi-solid matrix is disrupted and becomes a looser structure. This may partly explain why we don't see an increase in bacterial diversity with melted cheese."
A nation's favourite under scrutiny
The findings will be unwelcome news for many: polling consistently shows that cheese on toast is the country's most popular snack, with nearly one in four people naming it as their go-to treat when hungry.