The worst foods for your gut health, according to experts

Science is constantly learning more about how the gut interacts with the rest of the body. And with every breakthrough, experts are updating their advice on the foods we need to include in our diet.

We're instructed to eat 30 plant points a week, to increase our fibre and told that the Mediterranean 'blue zone' diet could be the key to living a long life.

Nutritional scientist Toral Shah, external explains our gut microbiome "breaks down foods, absorbs nutrients and fights off harmful pathogens.

"From digestion to immune response, gut health plays a crucial role in maintaining our overall health and wellness, including impacting things like mental health, IBS, liver health and obesity."

Like every part of our body, our gut is completely unique, which means the food we eat affects us all differently.

That being said, there are definitely foods we should prioritise for good gut health and those we should avoid. Here's what the experts say…

UPFs are foods that have been made using artificial ingredients such as flavour enhancers, emulsifiers and additives – like sausages, cereal and ice cream – and are often high in calories but low in nutrients.

It's not known exactly why UPFs are bad for our health but a recent study on them found links to 32 health issues, external, with their effect on the gut microbiome a key factor.

However you don't have to give up UPFs entirely. Experts suggest you follow the 80/20 rule – where you try to eat healthy 80% of the time and allow yourself treats the remaining 20% of the time.

Foods cooked in oil or deep-fried contain saturated and trans fats, which can be difficult to digest and affect your gut microbiome, external.

Stir-frying is a good way to reduce your fat consumption, making it easier for your gut to digest, and has less of a negative impact on your good gut bacteria.

If you can't break up with fried foods completely, the 80/20 rule can apply here too.

Sadly, biscuits and cakes are the type of foods that are high in refined sugar and could harm your gut if eaten too frequently. Sugar can cause inflammation in your gut, external, which can harm the good bacteria that we all need.

High-sugar foods don't just include bakes and sweets, though. Fruit juices, yoghurts, sauces, soups and even salad dressings can all contain surprising amounts of sugar, so it's always worth checking the label when shopping.

The NHS recommends adults have no more than 30g, external (that's about seven sugar cubes) of free sugars per day.

Free sugars are the sort added to food or drinks, and those found naturally in honey, syrups and unsweetened fruit and vegetable juices, smoothies and purees.

So does that mean you should switch to artificial sweeteners? Although popular because they're low in sugar and calories, experts aren't clear on their impact on our gut health, with conflicting results across animal and human studies.

More research needs to be done in this area. But, rest assured, all sweeteners used in the UK must be approved for safety before they're used in food and drink.

Nutritionist Rohini Bajekal, external says alcohol can be one of the worst lifestyle choices for our gut health. She explains it can disrupt the balance of good and bad bacteria and cause chronic inflammation, external, irritating cells in the stomach lining.

While moderate drinking is unlikely to cause significant damage, if you drink more than the 14 units a week that's recommended, external you may experience bloating, constipation and discomfort.

There is potentially one exception to the rule, though. Researchers at Kings College, London, found red wine could actually help your gut, external.

Lead author, Dr Caroline Le Roy said: "While we have long-known of the unexplained benefits of red wine on heart health, this study shows moderate red wine consumption is associated with greater diversity and a healthier gut microbiota that partly explain its long debated beneficial effects on health."

Originally published July 2024. Updated February 2026

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