Malnutrition in children with food allergies

Malnutrition is probably not what most parents picture when they look at a child eating gluten-free crackers, oat milk yoghurt and a rotation of carefully selected safe foods. We often imagine malnutrition as something obvious: severe thinness, food scarcity or deprivation. But modern malnutrition can hide in plain sight.

A child may eat regularly, appear well and even gain weight while still lacking nutrients essential for growth, brain development and immune function. A toddler surviving on beige foods. A child drinking plant-based milk with very little protein. A teenager avoiding multiple food groups after online sensitivity testing. In these situations, calories may be adequate, but nutrition may not be.

This is becoming increasingly relevant in children with food allergies and restrictive diets.

For many families, allergy management understandably becomes focused on safety: checking labels, avoiding reactions and carrying emergency medication. But while attention is placed on what must be removed from the diet, another important question is often overlooked: what nutritional building blocks disappear at the same time?

How restrictive diets can affect nutrition

Childhood is a period of rapid growth and development. Nutrition does far more than fuel the body – it helps build bone, support brain development, regulate immunity and maintain the gut barrier.

And every time a major food group is removed, nutrients disappear with it. Milk contributes calcium, iodine and protein. Eggs provide protein, choline and B vitamins. Fish supplies omega-3 fats important for brain development. Wheat contributes fibre and fortified nutrients to many diets. The more foods removed, the harder nutritional balance becomes, particularly in early childhood [1,2].

At the same time, modern childhood diets are increasingly dominated by ultra-processed foods. Emerging research suggests that diets high in ultra-processed foods may be associated with increased allergy and atopic disease risk, although the relationship is likely complex and influenced by multiple factors [3]. Researchers believe these diets may affect immune health through altered gut microbiota, inflammatory pathways and poorer overall dietary quality.

Processing itself may also affect nutritional value. Ultra-processed foods are frequently exposed to high temperatures during manufacturing, which can reduce heat-sensitive vitamins, antioxidants and bioactive compounds. In some cases, foods remain calorie-dense while becoming nutritionally diluted.

This becomes particularly relevant during weaning and in children with very restricted diets. Commercial baby food pouches are convenient and heavily marketed as healthy options, yet some products may contain relatively low levels of important nutrients such as iron and protein while relying heavily on sweet puréed textures [4]. Public health experts have also raised concerns that frequent pouch feeding may reduce exposure to varied textures and flavours during an important stage of feeding development [5,6].

The issue is not occasional convenience foods. For many families, they are practical and helpful. The concern is when processed foods begin replacing nutrient-dense meals and repeated exposure to family foods during critical developmental stages.

A UK study found that children with food allergies were more likely to be underweight than the general population, particularly when three or more foods were excluded from the diet [7]. Interestingly, some children were overweight despite dietary restriction, highlighting an important point: malnutrition is not always visible.

When eating becomes more complex

And this is something we often see clinically.

A patient I recall working with was an autistic 8-year-old girl with multiple food allergies and later diagnosed with ARFID (Avoidant Restrictive Food Intake Disorder). Her mother had done everything “right” – she had sought specialist help, followed advice carefully and was deeply committed to supporting her daughter’s nutrition. But feeding had become incredibly challenging.

Her daughter strongly preferred beige, processed foods such as biscuits, cookies, pasta and processed meats, was allergic to dairy and would only drink fortified soya milk. Despite ongoing efforts, she would not eat a single fruit or vegetable and could immediately detect if vitamins or supplements had been added to foods.

Eventually, through careful nutritional support, we managed to introduce a flavourless vitamin sprinkle into her fortified soya milk, which, alongside the nutrients already added to the drink, allowed us to just about meet her nutritional requirements despite the limited range of foods she accepted.

What stayed with me most was the level of guilt and anxiety her mother carried. She constantly worried that people judged her for feeding her daughter processed foods, when in reality she was managing an extremely complex feeding situation with enormous care and dedication.

And this is exactly why conversations around food allergies, processed foods and nutrition need nuance and compassion. Sometimes the goal is not achieving the “perfect” diet immediately, but supporting nutritional adequacy safely while gradually working towards dietary expansion with specialist help.

Food allergies may affect far more than nutrient intake alone. Fear of reactions, sensory sensitivities, stressful mealtimes and selective eating can all contribute to dietary narrowing over time [8].

The risks of unnecessary food restriction

At the same time, experts are increasingly concerned about unnecessary food restriction. As food allergies become more widely recognised, more families are turning to broad allergy panels, online food sensitivity tests and precautionary elimination diets. But this is where things can become complicated.

A positive allergy test does not always equal clinical allergy – but the nutritional consequences of eliminating foods are very real. Research has shown that indiscriminate food allergen panel testing frequently results in unnecessary food avoidance and misdiagnosis [9]. Positive tests may reflect sensitisation rather than true allergy, which is why allergy testing should always be interpreted alongside symptoms and clinical history by qualified healthcare professionals.

The risks of unnecessary restriction have been illustrated dramatically in case reports of children developing severe malnutrition after being placed on overly restrictive diets following misdiagnosis and the use of unproven testing methods [10].

This highlights an important point: the safest diet is not the most restrictive diet. It is the narrowest diet that safely manages confirmed allergy while preserving nutritional adequacy and dietary diversity [11].

Supporting children with food allergies

For parents, this does not mean fearing elimination diets when they are genuinely needed. In many children, avoiding allergenic foods is essential and potentially life-saving. Rather, it means recognising that removing foods changes more than just the menu.

Children with food allergies may benefit from:

• regular growth monitoring
• review of unnecessary dietary restrictions
• support from allergy specialists and dietitians
• appropriate nutritional supplementation where needed
• and maintaining the widest safe variety of foods possible

Ultimately, food allergy management is about more than avoiding reactions alone. Childhood is a period of rapid growth, immune education and developmental change. The challenge is not simply removing foods safely, but ensuring children continue to receive the nutrition, diversity and developmental experiences needed to thrive.

References

1. Malnutrition and Allergies: Tipping the Immune Balance towards Health
   Vassilopoulou E, et al. Malnutrition and Allergies: Tipping the Immune Balance towards Health. J Clin Med. 2024;13(5).
2. Lack of iron, zinc, and vitamins as a contributor to the etiology of atopic diseases
   Peroni DG, et al. Lack of iron, zinc, and vitamins as a contributor to the etiology of atopic diseases. Front Nutr. 2023;10.
3. Ultra-processed foods and allergic disease risk. Ultra-processed foods and allergic disease risk. 2024. Available via PubMed: https://pubmed.ncbi.nlm.nih.gov/39254357/
4. Commercial Baby Foods: Nutrition, Marketing and Motivations for Use – A Narrative Review
5. Australian Department of Health and Aged Care. Improving Commercial Foods for Infants and Young Children.
6. National Health Service. Start for Life: What to Feed Your Baby Around 6 Months.
7. Malnutrition in children with food allergies in the UK. Meyer R, De Koker C, Dziubak R, Venter C, Dominguez-Ortega G, Cutts R, Yerlett N, Skrapak AK, Fox AT, Shah N. Malnutrition in children with food allergies in the UK. J Hum Nutr Diet. 2014;27(3):227–235.
8. Identifying Children at Risk of Growth and Nutrient Deficiencies in the Food Allergy Clinic. Venter C, Meyer R, Bauer M, Bird JA, Fleischer DM, Nowak-Wegrzyn A, et al. Identifying Children at Risk of Growth and Nutrient Deficiencies in the Food Allergy Clinic. J Allergy Clin Immunol Pract. 2024. https://doi.org/10.1016/j.jaip.2024.01.027
9. Food Allergen Panel Testing Often Results in Misdiagnosis of Food Allergy
   Bird JA, et al. Food Allergen Panel Testing Often Results in Misdiagnosis of Food Allergy. J Pediatr. 2015.
10. Misdiagnosed Food Allergy Resulting in Severe Malnutrition in an Infant
    Alvares M, Kao L, Mittal V, Wuu A, Clark A, Bird JA. Misdiagnosed Food Allergy Resulting in Severe Malnutrition in an Infant. Pediatrics. 2013;132(1):e229–e232.
    https://doi.org/10.1542/peds.2012-2362
11. Nutritional Management of Children with Food Allergies. Curr Treat Options Allergy. 2022.
    https://doi.org/10.1007/s40521-022-00320-7