What Predicts Flares in Crohn’s Disease and Ulcerative Colitis? Diet, Calprotectin and the PREdiCCt Study

By Dr Pranab Gyawali, Consultant Gastroenterologist (UK-trained) in Dubai
Published: 04 May 2026

In this video, I discuss the PREdiCCt study, published in Gut in January 2026. This was a large UK prospective study looking at diet, inflammation markers and flare risk in patients with Crohn’s disease and ulcerative colitis who felt well at the start. (Read the PREdiCCt study in Gut)

I find this study particularly useful because it reflects a real clinical problem: patients may feel better, but the bowel may not be truly quiet.

In my own practice, I try to discuss diet with patients whenever possible, but I also recognise the reality of a busy IBD consultation. There are medicines to review, blood results, stool tests, scans, endoscopy findings, biologic decisions, insurance approvals and safety checks. Diet can easily get squeezed into the last few minutes. That is why studies like PREdiCCt are useful. They give us a more structured way to talk about diet, symptoms and inflammation without pretending there is one simple diet answer for every patient.

The key message is simple: diet matters, but guessing from symptoms alone is not enough. In Crohn’s disease and ulcerative colitis, we also need to monitor inflammation properly.

What was the PREdiCCt study?

The PREdiCCt study stands for PRognostic effect of Environmental factors in Crohn’s and Colitis.

It was a large UK study published in Gut in January 2026. It followed more than 2,600 people with inflammatory bowel disease, including both Crohn’s disease and ulcerative colitis.

The important point is that these patients were not selected because they were actively flaring. They were people who felt well and thought they were in remission at the start of the study.

The researchers then followed them for just over four years to see who went on to flare.

This makes the study very relevant to daily practice because many patients ask the same question:

“If I feel well now, what can predict whether I may flare later?”

Why is this study useful for Crohn’s and ulcerative colitis patients?

The study is useful because it looked at the problem in a realistic way.

It did not simply ask whether one food is “good” or “bad”. It looked at diet, symptoms, blood inflammation, stool inflammation and future flare risk.

That matters because inflammatory bowel disease is not just about symptoms. A patient may feel reasonably well but still have hidden inflammation in the bowel.

This is especially important in Crohn’s disease and ulcerative colitis because the aim is not only to reduce diarrhoea, bloating, urgency or pain. The aim is also to control inflammation, prevent complications, reduce steroid exposure and protect the bowel long term.

What did the PREdiCCt study find?

The most important finding was not one specific food.

It was not dairy.

It was not gluten.

It was not one special diet.

The strongest signal for future flare was whether there was still inflammation present when the patient felt well, especially measured by faecal calprotectin.

Faecal calprotectin is a stool inflammation test. It helps us understand whether there may be ongoing inflammation in the bowel, even when symptoms appear controlled.

In the PREdiCCt study, patients with low faecal calprotectin had the lowest risk of future flare. Patients with raised faecal calprotectin had a higher risk. When faecal calprotectin was above 250, the risk of a true inflammatory flare was much higher.

That is one of the most practical messages from the study.

You can feel well, but the bowel may not be truly quiet.

What did the study show about diet?

This is where the study becomes very interesting.

The PREdiCCt study did not find one simple diet rule for everyone with inflammatory bowel disease.

It did not show that stopping dairy prevents flares.

It did not show that stopping gluten prevents flares.

It did not show that one diet works for every patient with Crohn’s disease or ulcerative colitis.

The clearest diet signal was in ulcerative colitis. People whose usual diet was very meat-heavy had about double the risk of an objective flare compared with those with the lowest meat intake.

That does not prove meat directly caused the flare. It may be that meat itself matters. It may also be that people eating a very meat-heavy diet had other diet or lifestyle patterns that increased risk.

This is why diet research in IBD is so difficult. We can find signals, but we have to be careful not to turn those signals into overconfident rules.

Still, I would not ignore this finding. It does challenge the online idea that very meat-heavy diets are automatically good for colitis. I do not think the evidence supports that.

Does this mean meat causes ulcerative colitis flares?

No. That would be too strong.

The PREdiCCt study was observational. That means it can show an association, but it cannot prove that meat directly caused a flare.

The safer interpretation is this:

A very meat-heavy usual diet was linked with a higher risk of objective flare in ulcerative colitis.

That is a signal worth taking seriously, but it should not be turned into panic.

It does not mean every patient with ulcerative colitis must become vegetarian.

It does not mean one portion of meat causes a flare.

It does not mean bone broth, occasional meat, or a balanced diet containing some animal protein is the same as a long-term meat-heavy eating pattern.

The concern is more about the overall pattern over time.

Did the study show that dairy-free or gluten-free diets prevent flares?

No. This is an important point.

Many patients with Crohn’s disease or ulcerative colitis try dairy-free or gluten-free diets. Some feel better when they do this, especially if they have lactose intolerance, bloating, IBS overlap, or individual food sensitivity.

But this study did not show that stopping dairy or stopping gluten clearly prevents inflammatory flares in IBD.

That does not mean your symptoms are not real.

It means symptom triggers and inflammation triggers are not always the same thing.

A food may worsen bloating, gas, urgency or diarrhoea without being the main driver of bowel inflammation.

That is why diet needs to be personalised, but inflammation still needs to be monitored.

What is the difference between symptom control and disease control?

Symptom control means you feel better.

Disease control means the inflammation is actually under control.

They often go together, but not always.

For example, a patient may have less diarrhoea after cutting out dairy, reducing fibre or eating a more bland diet. That may be useful for symptoms, especially during a flare. But that does not automatically mean the underlying Crohn’s disease or ulcerative colitis inflammation has settled.

The reverse can also happen. Some patients have ongoing urgency, bloating or bowel disturbance even when inflammation markers are normal. That may reflect IBS overlap, bile acid diarrhoea, food intolerance, SIBO, post-surgical bowel changes or other factors.

This is why the distinction matters.

Diet can help symptoms.

But we still need objective tests to know whether inflammation is truly controlled.

What does this mean for patients trying to find the right IBD diet?

The way I think about diet in IBD is that there is no single list that works for everyone.

I do not usually give patients one rigid food list and say, “This is the Crohn’s diet” or “This is the ulcerative colitis diet.” I do not think the evidence supports that approach.

What I do recommend is a structured way of thinking.

During a flare, or soon after surgery, some patients may need simpler foods temporarily. That may mean softer foods, lower-fibre foods, less spice, less fat and meals that are easier to tolerate. That is not because these foods are “curing” inflammation. It is because they may reduce symptoms while the bowel is sensitive.

When patients are stable or in remission, I usually try to move them gradually toward a broader, more Mediterranean-style eating pattern. That does not mean a strict Mediterranean diet with rigid rules. It means more variety, more plant-forward foods where tolerated, olive oil, fish, nuts, legumes and whole grains if the patient can manage them.

But I individualise this heavily.

A patient with stricturing Crohn’s disease is different from a patient with ulcerative colitis in remission. A patient after bowel surgery is different from a patient with bloating and IBS overlap. A patient with lactose intolerance is different from someone who tolerates dairy perfectly well.

So I use diet to improve symptoms, nutrition and quality of life.

But I do not use diet alone to judge whether the disease is controlled.

That still needs objective monitoring.

Should Crohn’s disease and ulcerative colitis patients follow a Mediterranean-style diet?

In general, yes, when patients are stable or in remission, I often recommend moving toward a Mediterranean-style diet.

But I do not mean this as a rigid prescription.

I am not saying every patient must eat the same foods, or that every patient must suddenly increase fibre, beans, nuts or raw vegetables. That would be wrong, especially for some Crohn’s patients with strictures or patients recovering after surgery.

What I mean is that, as a long-term direction, a Mediterranean-style pattern is usually more sensible than a highly restricted, highly processed or very meat-heavy diet.

For me, the practical direction is more variety if tolerated, more plant-based foods if tolerated, olive oil, fish, less ultra-processed food, and less reliance on very meat-heavy patterns.

But the phrase “if tolerated” matters.

I individualise the diet around the patient in front of me.

If someone tells me dairy worsens their symptoms, we work around that.

If high fibre causes pain because of a stricture, we do not push fibre blindly.

If someone is losing weight, has anaemia, low albumin or has just had surgery, nutrition becomes a priority.

So yes, I often use Mediterranean-style eating as the long-term direction.

But I do not use it as a strict rulebook.

What role does faecal calprotectin play in predicting IBD flares?

Faecal calprotectin is one of the most useful non-invasive tools in inflammatory bowel disease.

It is not perfect, but it helps detect bowel inflammation.

The PREdiCCt study reinforced its importance. In patients who felt well at the start, baseline faecal calprotectin was the strongest signal for future flare risk.

This matters because many patients make dietary changes based only on symptoms.

Symptoms are important, but they are not always reliable enough on their own.

If faecal calprotectin remains raised, the bowel may still be inflamed even if symptoms are quieter.

That is why monitoring faecal calprotectin can be useful in Crohn’s disease and ulcerative colitis, especially when deciding whether symptoms reflect active inflammation or something else.

What should patients take away from this study?

Many patients are trying very hard. They stop dairy, stop gluten, avoid meat, reduce fibre, try keto, try carnivore, try supplements, or keep a very restricted diet because they are afraid of flaring.

I understand why they do this.

But this study reminds us that the strongest warning signal was not one single food. It was hidden inflammation, especially faecal calprotectin.

That is the key lesson.

Find the diet that suits your symptoms.

But do not confuse symptom control with disease control.

If your symptoms improve after changing diet, that is useful. But it does not automatically prove that bowel inflammation has settled.

You still need to know whether the disease is truly quiet.

That is where faecal calprotectin, blood tests, endoscopy, imaging and proper IBD follow-up matter.

When should a patient seek medical advice?

Patients with Crohn’s disease or ulcerative colitis should seek medical advice if they develop rectal bleeding, persistent diarrhoea, weight loss, fever, night-time symptoms, severe abdominal pain, vomiting, anaemia, rising inflammatory markers, or symptoms after recent surgery.

Diet adjustment may help symptoms, but it should not delay assessment of active inflammation.

This is particularly important if faecal calprotectin, CRP, haemoglobin, albumin or endoscopy findings suggest active disease.

If you wish to discuss this further or would like to make an appointment, please use the booking form on this page. Expect a response within 12 business hours.