Does sugar feed intestinal inflammation?

If your child has Crohn’s disease or ulcerative colitis, you may have heard that sugar feeds inflammation in the gut or that cutting it out could help control IBD.

Sugar and diet are increasingly being studied in relation to gut health, the gut microbiome and inflammatory bowel disease. Some research has linked diets high in added sugar with an increased risk of developing IBD, while other studies have explored how dietary patterns may influence the intestinal environment.

But does sugar directly cause inflammation in a child who already has IBD? Can eating sweets trigger a flare? And should parents be restricting sugar?

The evidence is more complicated than many headlines suggest. A diet high in added sugar may have undesirable effects on overall health and could play a role in IBD risk, but sugar has not been proven to directly trigger intestinal inflammation or cause a flare every time a child eats it. 

🔬 What does the research say about sugar and IBD?

Researchers are investigating whether diets high in added sugar and highly processed foods may contribute to changes in the gut microbiome and the body's inflammatory responses.

A 2024 umbrella review examining evidence from multiple systematic reviews and meta-analyses identified refined sugar intake among the dietary factors associated with an increased incidence or progression of IBD. However, the evidence varied in quality, and associations do not prove that sugar directly causes inflammation.

Read the full 2024 review.

A 2025 systematic review and meta-analysis of 45 studies also found an association between higher added sugar intake and an increased risk of developing Crohn’s disease and ulcerative colitis. Higher consumption of sugar-sweetened drinks was also associated with increased IBD risk. However, the findings cannot establish that sugar causes IBD, and they do not show that removing sugar will induce remission in children who already have the condition.

Read the 2025 systematic review and meta-analysis.

There are several important limitations to keep in mind:

• Many studies investigate the risk of developing IBD, rather than what happens when someone with established IBD eats sugar.

• People who consume more added sugar may also eat more highly processed foods or have other lifestyle factors that influence health.

• Research findings do not establish a specific amount of sugar that triggers inflammation.

• Studies in adults cannot automatically be applied to children.

Overall, the research suggests that diet may influence the gut environment, but it has not established that sugar directly causes intestinal inflammation in every person with IBD.

🦠 How might sugar affect the gut microbiome?

The gut microbiome is the community of bacteria and other microorganisms living in the digestive tract. These microorganisms interact with the immune system and help maintain the intestinal lining.

Researchers are interested in whether a diet high in added sugar and low in fibre may influence the balance of gut microorganisms and the substances they produce.

Some proposed mechanisms include:

• Changes in gut bacteria: Dietary patterns can influence which microorganisms thrive in the intestine.

• Changes in the intestinal environment: What we eat can affect the nutrients available to gut bacteria and the substances they produce.

• Effects on the gut barrier: Researchers are investigating whether certain dietary patterns affect the integrity of the intestinal lining.

• Immune responses: Changes in the gut microbiome may influence how the immune system interacts with the intestinal environment.

These are active areas of research. Much of the mechanistic evidence comes from laboratory studies and animal research, so it cannot be assumed that eating sugar produces the same effects in a child with IBD.

It is also important to remember that sugar is not the only dietary factor being studied. Overall eating patterns, fibre intake, food additives and the amount of highly processed food in the diet may all be relevant.

🍭 Does eating sugar trigger an IBD flare?

Not necessarily.

An IBD flare involves active inflammation in the digestive tract. However, children with IBD can experience digestive symptoms without having increased inflammatory activity.

Some children may notice more bloating, abdominal discomfort or diarrhoea after consuming certain sugary foods or drinks. This can happen for several reasons.

For example, drinks containing large amounts of sugar may be difficult for some people to tolerate, while certain sweeteners, such as sorbitol, can contribute to gas or diarrhoea.

These symptoms can be uncomfortable, but they do not automatically mean that the underlying IBD inflammation has worsened.

Conversely, a child can have active intestinal inflammation without obvious symptoms after eating a particular food.

If your child repeatedly experiences symptoms after certain foods, keeping a simple food and symptom diary may help identify patterns. If symptoms persist or worsen, discuss them with their IBD team rather than assuming sugar is responsible.

🥤 Are sugary drinks different from sugar in food?

Sugar-sweetened drinks are an important area of research because they can provide substantial amounts of added sugar without contributing much fibre or other nutrients.

Examples include:

• Soft drinks and fizzy drinks with added sugar.

• Sweetened iced teas.

• Energy drinks.

• Fruit drinks and cordials with added sugar.

• Sweetened coffees and other flavoured beverages.

Some observational studies have linked higher consumption of sugar-sweetened drinks with an increased risk of developing IBD. However, this does not prove that these drinks cause flares in children who already have Crohn’s disease or ulcerative colitis.

Read the research

Whole fruit is different from a sugary drink. Fruit provides water, fibre and a range of nutrients, and its natural sugar is contained within the food.

Fruit juice and smoothies can be tolerated differently from whole fruit, particularly when consumed in large quantities. Your child's individual tolerance matters, especially during a flare.

🍎 Should parents reduce sugar in a child's diet?

It can be reasonable to limit excessive added sugar as part of a balanced diet, but there is no evidence-based requirement for every child with IBD to follow a completely sugar-free diet.

A practical approach is to focus on the overall quality and variety of your child's diet rather than trying to eliminate every source of sugar.

You might consider:

• Offering water regularly instead of relying on sugary drinks.

• Including a variety of fruits and vegetables, according to your child's tolerance.

• Providing adequate protein, carbohydrates and healthy fats to support growth.

• Choosing a range of nourishing foods rather than relying heavily on highly processed snacks.

• Keeping treats as a normal part of family life rather than labelling foods as forbidden.

These are general healthy eating principles, not a specific treatment for intestinal inflammation.

Some children may need a different approach during a flare, particularly if they have poor appetite, weight loss or difficulty tolerating food. Their nutritional needs should take priority, and an IBD dietitian can help tailor recommendations.

⚖️ What about natural sugars, honey and fruit?

Not all sources of sugar are nutritionally equivalent.

Sugar naturally present in whole fruit is accompanied by fibre, water and other nutrients. Milk contains lactose, a naturally occurring sugar, while honey and syrups contain sugars that are generally considered added or free sugars in dietary guidance.

There is no good evidence that all these foods need to be removed from the diet of every child with IBD.

Some children may have specific intolerances or find particular foods difficult to digest. For example, lactose can cause symptoms in someone who has difficulty digesting it, but that does not mean lactose itself is causing IBD inflammation.

If a particular food consistently causes symptoms, seek individualised advice before eliminating an entire food group.

🧒 Why is avoiding excessive restriction important for children?

Children with IBD need enough energy and nutrients to grow, develop and recover from illness.

Restricting too many foods can make it harder to meet their nutritional requirements, especially if they already have a reduced appetite, food anxiety, weight loss or nutrient deficiencies.

A strict sugar-free diet can also make eating more stressful for children and families without providing a proven benefit for IBD remission.

Rather than focusing on perfection, aim for a balanced, flexible approach that supports your child's nutritional health and relationship with food.

If you are concerned about your child's diet, an IBD dietitian can help identify practical changes without unnecessarily restricting foods they enjoy.

🩺 Can cutting out sugar help induce remission?

There is currently insufficient evidence to recommend eliminating sugar as a treatment for active Crohn’s disease or ulcerative colitis.

Although research has identified associations between high added sugar intake and IBD risk, this is different from demonstrating that sugar restriction can reliably reduce inflammation or induce remission in someone who already has IBD.

Treatment decisions should be guided by your child's gastroenterologist, using symptoms and appropriate investigations to assess disease activity.

If your child is experiencing a flare, do not delay medical advice while trying to remove sugar or other foods from their diet. Dietary changes should complement, rather than replace, the treatment plan recommended by their IBD team.

❤️ What should parents take away from the research?

Sugar and dietary patterns are important areas of IBD research, but the evidence does not support blaming sugar for a child's inflammation or assuming that a sugar-free diet will control their disease.

Reducing excessive added sugar can be part of a healthy eating pattern, particularly when it means replacing sugary drinks with water and making room for a wider variety of nourishing foods. However, there is no need to remove every sweet food from your child's diet in the hope of preventing a flare.

The most useful approach is to look at your child's overall nutrition, pay attention to their individual food tolerance and work with their healthcare team when symptoms change.

Your child does not need a perfect diet to manage IBD. Good nutrition can support their health, but effective medical care remains essential for controlling intestinal inflammation.

📚 Further reading

• Crohn’s & Colitis Foundation: How diet impacts IBD — Explains the relationship between food, digestive symptoms and inflammation.

• Dietary sugar and sweetened beverage intake and IBD risk: systematic review and meta-analysis — Reviews research on added sugar, sweetened drinks and the risk of developing IBD.

• Diet, food and nutritional exposures and IBD: umbrella review — Examines evidence linking dietary patterns with IBD incidence and progression.

• American Gastroenterological Association: Diet and nutritional therapies in IBD — Provides clinical guidance on nutrition and IBD management.