Cheese on toast is bad for your gut health - but unmelted cheddar has a positive effect

Published: 22:30, 23 May 2026 | Updated: 22:48, 23 May 2026 It may be one of our favourite snacks, but cheese on toast could be bad for your gut health, research shows. Scientists found that eating unmelted cheddar had a positive effect on the gut microbiome – the intestinal mixture of bacteria and other organisms thought to control everything from mood to our immune systems. Solid cheddar increased the diversity of these bugs – keeping the microbiome in good order. But when the cheese was melted, the diversity was reduced, harming gut health. Researchers from University College Dublin wanted to measure what effect cheddar cheese had on this delicate balance. They tracked 69 volunteers over six weeks. Some ate 120g of unmelted cheese a day, while others consumed the same amount, but in melted form. At the end of the experiment, the researchers measured changes in participants' gut bacteria. They found cheddar was good for the microbiome, but when it was melted for cheese on toast the benefits were largely undone. Heating hard cheese damages its structure, making it harder for the body to absorb beneficial nutrients, according to the scientists. Cheese on toast is bad for your gut health, a study has found In a report, published in Frontiers In Microbiology, the researchers said: '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.' Polls show cheese on toast is the nation's favourite snack, with nearly one in four naming it as their go-to treat when peckish. No comments have so far been submitted. Why not be the first to send us your thoughts, or debate this issue live on our message boards. By posting your comment you agree to our house rules. Do you want to automatically post your MailOnline comments to your Facebook Timeline? Your comment will be posted to MailOnline as usual. Do you want to automatically post your MailOnline comments to your Facebook Timeline? Your comment will be posted to MailOnline as usual We will automatically post your comment and a link to the news story to your Facebook timeline at the same time it is posted on MailOnline. To do this we will link your MailOnline account with your Facebook account. We’ll ask you to confirm this for your first post to Facebook. You can choose on each post whether you would like it to be posted to Facebook. Your details from Facebook will be used to provide you with tailored content, marketing and ads in line with our Privacy Policy.