Many parents of school-aged children tell or ask me:
“Milk seems to upset my child’s stomach…” “…should we cut these foods out completely?”
Digestive discomfort linked to certain sugars is common in older children – and very often manageable without fear or extreme diets.
What is sugar malabsorption?
Sugar malabsorption means the gut has difficulty digesting or absorbing certain carbohydrates.
These sugars then travel to the large intestine, where bacteria ferment them – producing gas and discomfort.
The most common ones in children are:
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Lactose (milk sugar)
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Fructose (fruit sugar)
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Sorbitol (found in some fruits and sweeteners)
This is a digestive issue, not an immune reaction.
Lactose intolerance – what it is (and what it isn’t)
What lactose intolerance is
Lactose intolerance happens when the gut produces less lactase, the enzyme that breaks down lactose.
This leads to:
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Bloating
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Gas
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Abdominal pain
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Loose stools after dairy
It usually appears:
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In older children or adolescents
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Gradually over time
What lactose intolerance is NOT
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It is not a cow’s milk allergy
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It does not cause blood in stool
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It does not cause eczema or breathing problems
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It does not affect growth if managed sensibly
Many parents worry they’ve missed an allergy
– but lactose intolerance is about digestion, not danger.
Fructose and sorbitol malabsorption
Some children have difficulty absorbing:
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Large amounts of fruit
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Fruit juices
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Apples, pears, mangoes
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Products containing sorbitol
This can lead to:
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Bloating
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Loose stools
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Abdominal pain, especially later in the day
This does not mean fruit is “bad” – it often means quantity and timing matter.
A child who reacts to a large glass of apple juice but tolerates a small portion of fresh apple is showing a dose-dependent response – not a food allergy. This distinction matters for how you manage it.
What about wheat or gluten?
Wheat-related tummy symptoms are common, but important distinctions are needed.
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Coeliac disease is an immune condition and must be ruled out if suspected
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Non-coeliac wheat sensitivity is less well defined
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Many symptoms blamed on wheat are actually related to fermentable carbohydrates
This is why coeliac disease must always be tested before any gluten-free diet is started. Once gluten is removed from the diet, the blood test for coeliac disease becomes unreliable. Always test first.
This is why blanket elimination is rarely helpful.
How are these conditions diagnosed?
Diagnosis usually involves:
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Careful symptom history
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Growth assessment
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Sometimes breath testing (with limitations)
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Dietary observation under guidance
Tests are supportive – the child’s overall health and growth matter most.
Hydrogen breath tests for lactose and fructose malabsorption are available but have significant limitations in children – false positives are common and results must be interpreted alongside clinical history, not in isolation.
When to relax vs when to worry
You can usually relax if:
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Symptoms occur after specific foods
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Your child is growing well
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Pain improves after passing gas or stool
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There is no blood in stool
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Energy and appetite are good
Red flags – when to see a doctor
Please seek medical advice if symptoms are associated with:
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Weight loss or faltering growth
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Persistent diarrhoea
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Blood in stool
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Night-time symptoms
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Family history of coeliac disease or inflammatory bowel disease
These signs don’t mean something serious is present – but they need assessment.
Should foods be removed completely?
In most cases:
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Total elimination is unnecessary
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Smaller portions work better than avoidance
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Variety protects nutrition
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Fear around food increases symptoms
The goal is confidence with food – not control.
A reassuring closing thought
Digestive sensitivity to sugars is common in growing children and usually reflects how the gut handles certain foods – not illness.
With understanding and balance, most children can eat a wide variety of foods without long-term problems.
Clear information can make worrying feel lighter.
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This article reflects guidance used by paediatricians in daily clinical practice.
Sources & medical guidance:
- ESPGHAN Committee on Nutrition Position Paper: Sugar in Infants, Children and Adolescents – Fidler Mis et al. (2017)
- ESPGHAN/NASPGHAN Guidelines for Treatment of IBS and Functional Abdominal Pain in Children – Groen et al. (2025)
- NICE Guideline NG20: Coeliac Disease – Recognition, Assessment and Management (2015, updated 2020)
- Rome IV Criteria for Paediatric Functional Gastrointestinal Disorders – Hyams et al. (2016)
- Rome V Criteria for Paediatric Disorders of Gut-Brain Interaction – Hyams et al. (2026)