Inflammatory Bowel Disease (IBD) and ultra-processed foods (UPFs): a dietitian's guide
Ultra-processed foods are definitely in the spotlight right now, but for people with Crohn's and colitis, the claims they destroy gut health are causing a lot of food fear.
Living with IBD already feels like playing detective, constantly trying to find ‘safe' foods. With so much conflicting advice online, the last thing this community needs is more demonised foods.
As an IBD dietitian, I help people with IBD cut through the noise. So, let’s unpack the science on UPFs and IBD and what’s important beyond the food label.
What Are Ultra-Processed Foods?
Most of the food we eat is processed in some way - think freezing, canning or drying to improve safety, shelf life or taste.
To make it simple, researchers use the NOVA classification, which breaks food down into four groups:
Unprocessed or Minimally Processed: Whole foods such as fresh fruit, vegetables, nuts or eggs.
Processed Culinary Ingredients: Minimally process foods from group 1 - oils, butter, sugar and salt.
Processed Foods: Simple combinations. Freshly baked bread (flour, water, salt, yeast), canned vegetables in brine or cheeses.
Ultra-Processed Foods (UPFs): Industrial creations. They often contain ingredients you wouldn't find in a home kitchen, like emulsifiers, thickeners, and artificial flavours. Examples include ready to eat snacks, ready meals, flavoured yoghurts, protein bars and breakfast cereals.
NOVA is not a nutrition guide.
NOVA categorises food based on level of processing and doesn’t consider nutrient content but UPFs are not nutritionally equal. It is often assumed UPFs contain high levels of fat, sugar and salt, and although this is the case for some, it is not true for all. Fast food options, cakes and sugary drinks are in the same category as fortified dairy-free milks, breakfast cereals and supermarket wholegrain breads. But these things are not similar nutritionally. NOVA also doesn’t recognise foods in groups 1 or 2 which evidence shows links to chronic conditions, such as red meat.
Do UPFs damage my gut?
Much of the concerns around UPFs and gut health come from observational research. While these studies suggest a connection between high UPF intake and IBD, they don't prove that one causes the other. A diet high in UPFs can also be low in foods good for the gut - like fibre, fruits and vegetables, which could be the real issue, not the processing itself.
Should I worry about the additives in UPFs?
Researchers are looking at the additives in some UPFs, specifically emulsifiers, colourings and sweeteners. Pre-clinical studies (early research in labs or with animals) show some additives might reduce ‘good' bacteria and weaken the gut lining, which could cause inflammation, especially for people who are genetically predisposed to it.
But what about human studies?
Research on sweeteners (aspartame, sucralose and saccharin) show short-term high intakes do not negatively affect the gut microbiome in healthy people.
One small study in healthy adults looked at CMC, a common emulsifier. After 11 days of consuming 15g of CMC, participants reported more bloating and stomach pain after meals. Results showed reduced gut bacteria diversity and bacteria moved closer to the gut lining, which has been linked with inflammation.
Currently, there is no strong evidence that UPFs are universally harmful to the gut in healthy people. Most data comes from:
Animal or lab models (which don't always translate to humans)
Very small groups of people
Short trial periods (often less than two weeks)
Can UPFs worsen my IBD?
The relationship between ultra-processed foods and IBD is still evolving and far from clear-cut.
There is some research which suggests people with IBD who consume a diet high in UPFs may have worse disease outcomes, including more frequent flares and a higher likelihood of needing surgery.
While these links sound concerning, they don't tell the whole story. The impact of UPFs seems to vary depending on whether you have Crohn's or colitis, the type of processed food, as well as which additives are involved.
When we look at human trials, the focus is on emulsifiers and results are conflicting.
In 2017 a study found 200mg of carogeenan lead to a higher risk of relapse in people with UC in remission. However, the results from a similar 2023 study found carogeenan had no difference in pro-inflammatory changes or gastrointestinal symptoms when compared with placebo.
In 2025, two trials looked at the impact of following a low-emulsifier diet in people with Crohn’s Disease. One study with 24 participants found no meaningful differences in disease activity, bowel inflammation or inflammatory markers. But a larger study involving 154 participants found a low-emulsifier diet reduced inflammation and had a higher likelihood of achieving remission.
Although this shows there may be some potential for a low-emulsifier diet in the management of Crohn’s Disease, this does not suggest the avoidance of emulsifiers for everyone with IBD. More high quality research (human control trials) is needed before recommendations can be made. At the moment, no human control trials have focused solely on UPFs in IBD.
It is worth noting there are already whole food elimination diets available for nutritional therapy in IBD, such as the Crohn’s Disease Exclusion Diet (CDED), The Specific Carbohydrate Diet (SCD), and the Ulcerative Colitis Exclusion Diet (UCED). These approaches exclude UPFs and, while they are beneficial for some people with IBD, they don’t work for everyone.
The reality of UPFs and IBD
People living with IBD tend to eat more UPFs and although studies may point towards poorer outcomes, the reality is far more nuanced than simple avoidance.
Focusing only on processing doesn’t take into account portion size, the overall balance of the diet, or social and cultural reasons for eating certain foods.
Labelling all UPFs ‘bad’ ignores the reality of living with a chronic illness. For people with IBD, total avoidance often isn’t an option. Here’s why:
Accessibility: Whole, unprocessed foods are often more expensive, not as readily available and have a shorter shelf life. Not everyone has the access to nutritious, affordable food.
Convenience: Preparing everything from scratch is often not realistic with IBD. When dealing with fatigue, pain, or a limited appetite, UPFs can play a helpful role in feeding the body.
Psychological toll of restriction: Labelling food 'good' or 'bad' causes guilt and shame. Strict food rules often lead to anxiety, food fear and disordered eating, which can be just as damaging to quality of life.
Nutritional impact: Not all UPFs are nutritionally equal and some can provide important nutrients for people with IBD — including wholegrain, breakfast cereals and breads, flavoured yogurts, and fortified plant-based milks. These contribute important nutrients at times when meeting nutritional needs may already feel challenging.
Summary:
UPFs aren’t the villain, especially when living with IBD. Although observational studies suggest a possible connection with high UPF intake, poor gut health and worse outcomes for people with IBD, the evidence is limited by the lack of good quality research. At present there is no strong evidence to recommend people with IBD to avoid all UPFs.
There is emerging evidence for trialling the reduction of emulsifiers in the management of Crohn’s Disease, but more good quality research is needed before a recommendation can be made. There is no evidence to suggest a blanket rule of avoiding emulsifiers for everyone with IBD.
Total avoidance of UPFs in those with IBD is not realistic and risks nutritional and psychological implications. Individual tolerance and nutritional needs matter far more than rigid food categories.
When looking at what to eat with IBD, dietary diversity is more important than a single food or ingredient. Focus on what you can add to your diet which benefits your body and your gut, not just what you should limit. A balanced diet focusing on fruits, vegetables, legumes, carbohydrates, and lean protein sources can also include UPFs.
When you’re living with IBD, the goal isn’t to eat perfectly 100% of the time, it’s about finding a diet that works for you, helps manage your symptoms and fuels your body.
