Ultra-Processed Foods Linked to Childhood Allergies & Asthma

If your child sneezes their way throughout the day, wakes up at night scratching, or reaches for their inhaler more often than you’d like, then you may have tried everything from antihistamines to steroid creams. What rarely gets discussed is the role that everyday foods may be playing. A growing body of research now links ultra-processed foods (UPFs) to a significantly higher risk of atopic conditions in children, including allergies, eczema, hay fever and asthma.

In my 30 years of clinical experience, the connection between what children eat and how their immune system behaves is probably one of the most underappreciated areas in children’s health. We are seeing more allergic children than ever before, and while genes play a role, they cannot explain the pace of the rise in cases, especially that of life-threatening allergies. Experts believe something in our modern environment is driving this, and the food most children eat every day is firmly in the picture.

Ultra-processed foods are everywhere in a typical child’s diet nowadays. From handy cereal bars and flavoured yoghurts to chicken nuggets, long-life bread, fizzy drinks, crisps, squash, instant noodles, and ready-made sauces. By definition (using the Brazilian NOVA classification system), these are products manufactured through industrial processes and using ingredients not typically found in home cooking, including emulsifiers, artificial flavours, sweeteners, preservatives, thickeners, colourings, and much, much more.

This is not about blaming parents. Modern life is busy, children are fussy, and these foods are specifically engineered to be convenient, affordable and appealing. But if your child is struggling with difficult-to-manage or worsening allergies, eczema, hay fever or asthma, understanding the food-immune connection could be one of the most powerful steps that you take.

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What does the research show?

The evidence linking a diet very high in UPFs to childhood allergic disease has been steadily mounting. A landmark population study using data from over 2,700 children and 4,000 adults found that higher UPF consumption was associated with current asthma in children, and those kids who ate the most UPFs had a 76% increased risk of developing asthma. The same study found an association between high levels of UPF intake and eczema, especially in girls.

Perhaps most significantly, the European Academy of Allergy and Clinical Immunology published a major task force report in 2024, which is a systematic review of 26 studies that concluded that excess dietary exposure to fructose in fizzy soft drinks, sugar intake, monosodium glutamate (MSG), advanced glycation end-products (harmful compounds formed when proteins or fats combine with sugars in the bloodstream) and other common UPF ingredients were associated with the increased likelihood of asthma, wheezing, food allergies, eczema and allergic rhinitis in children.

A 2025 review added to this story further, highlighting that emulsifiers, the ingredients that give processed foods their smooth, shelf-stable texture, are implicated in disrupting the gut barrier, altering gut bacteria and promoting inflammation, all of which can contribute to the development of allergic disease. These emulsifiers include Mono and Diglycerides which are found in some breads as well as Carrageenan added to dairy-free milks and some cream cheese products. Other common emulsifiers used in food manufacturing are Carboxymethylcellulose and Polysorbate-80, which are often found in ice cream and frozen meals as well as some baked products.

It is important to say that this research is largely observational and some are only animal studies, meaning we cannot definitively say UPFs cause allergies in every child (and we know these conditions are strongly genetic). But the consistency of findings across multiple countries and studies is evident, linking the disruption of UPF ingredients with atopic conditions, and the underlying mechanisms are now becoming much clearer.

The link with gut health

To understand how food and allergies connect, we need to start by understanding the effects of these ingredients on the gut. Your child’s digestive system is far more than a food-processing tube, and it is home to approximately 70% of their immune system. The trillions of bacteria, fungi and other microbes living there, collectively known as the gut microbiome, act as teachers and trainers for your immune cells, helping them learn the difference between harmless substances and proper threats.

When the gut microbiome is diverse and well-balanced, the immune system tends to be calmer and signals the good guys and bad guys appropriately. When the gut microbiome is disrupted, which is known as dysbiosis, the immune system can become overreactive, mounting responses to pollen, pet dander, certain foods or environmental triggers that it would otherwise ignore. This overreaction of the gut immune system is at the core of what allergic disease is.

Research confirms that gut dysbiosis in children is clearly linked to eczema, asthma and food allergy. Children with these conditions consistently show different gut microbiome profiles compared to unaffected children and they tend to have less microbial diversity, fewer protective bacterial families, and more of the inflammatory bacterial varieties.

So, what do UPFs have to do with all of this? Well, it turns out quite a lot!

Ultra-processed foods are usually low in dietary fibre, which is the fuel our beneficial gut bacteria need to survive and thrive. At the same time, these UPF foods are high in refined sugars and certain additives that actively feed the less helpful and unfriendly bacteria. The emulsifiers widely used in processed foods have been shown to physically disrupt the mucus layer lining the gut wall, essentially pulling down the security barrier that keeps bacteria and food particles where they belong.

There is also evidence that swallowing microplastics, many of which come from the packaging around ultra-processed foods and drinks, can tip the gut microbiome out of balance and weaken the integrity of the intestinal lining. On top of the plastic particles themselves, packaging can shed chemicals such as BPA and phthalates into the food, and this happens most readily with acidic or fatty foods, think fruit-based drinks and dairy products, or when food is heated in its packaging.

Altogether, this can lead to what is often called intestinal hyperpermeability (also known as leaky-gut), where tiny gaps open in the gut lining, allowing partially digested food proteins and bacterial compounds to slip into the bloodstream. When the immune system encounters these foreign particles where they should not be, it can mount an inflammatory response. Over time, this may prime a child’s immune system towards reactivity and allergy, looking like more itching, scratching, red skin and wheezing.

What should children be eating instead?

The good news is that healthy, nutritious foods protect against allergic disease, and cooking from scratch can really help to manage these conditions better. We are not talking about deprivation, and they can enjoy some of their favourite things from time to time (aim for UPFs to be 20% of their diet or less). Here I am talking about real food, made with real whole-food ingredients, in ways that nourish the gut and calm the immune system.

The key principles are:

Adopt the Mediterranean diet: Vegetables, fruits, pulses, beans, wholegrains and nuts feed the beneficial bacteria that keep the immune system balanced and healthy fats from olive oil, avocado and nuts help calm inflammation. Aim for as much variety and colour as possible, as different plant foods feed different gut bacterial species.
Include oily fish regularly: Salmon, mackerel, sardines and trout are rich in omega-3 fatty acids, which have anti-inflammatory properties. A meta-analysis found that fish consumption during the first year of life reduced the risk of both eczema and allergic rhinitis. Ideally aim for 2 portions per week and top up with an omega-3 supplement if they are not keen on eating fish or you find it hard to weave into your weekly routine.
Prioritise fermented foods: Natural yoghurt, kefir, miso and water kefir introduce beneficial bacteria directly to the gut and can help to populate the gut with the ‘good guys’.
Cook from scratch where possible: Even simple meals such as egg on good-quality toast, pasta with a lentil and vegetable sauce, or baked fish with rice and peas avoid many of the additives and emulsifiers that come packaged with UPFs.
Replace drinks: Swap fizzy drinks and squash/cordial for water, diluted fresh juices, homemade smoothies, coconut water or herbal teas. Carbonated soft drinks and fruit juices made from concentrate are among the most common UPF items to allergic disease in children.

Easy switches for parents stuck in a food rut

If your child is a selective eater and UPFs have become the path of least resistance, you are not alone but small changes really do add up. Here are some practical, low-battle swaps:

Breakfast

Instead of sugary cereal or cereal bars, try overnight oats with berries and a spoon of natural yoghurt, or opt for scrambled eggs on sourdough.
Instead of flavoured fruit yoghurt pouches, try plain full-fat yoghurt with a drizzle of honey and mashed banana or sweet mango.

Here is plenty of breakfast inspiration from my recipe blog.

Lunch

Instead of packaged white bread sandwiches with processed meat try wholegrain bread or pittas with homemade hummus and sliced cucumber or egg and cress sandwiches.
Instead of crisps and flavoured snack packets, try oatcakes with cheese, or vegetable sticks with guacamole.

Here are my top tips for easy and nutritious packed lunches.

Supper

Instead of chicken nuggets and chips, try homemade oven-baked fish goujons or chicken strips and coat in oats and baked rather than processed and fried. Try Lucinda’s Crispy Fish Fingers as a family favourite.
Instead of jarred pasta sauces loaded with sugar and additives, try roasted and blended tomatoes with olive oil, garlic and basil which can be ready in 20 minutes and freezable in batches.

Drinks and Snacks

Instead of squash and cordial, try giving them water with a slice of lemon or cucumber. Some children take well to sparkling water with a splash of fresh fruit juice as a fizzy treat without the additives.
Instead of chocolate biscuits and packaged cakes, try homemade energy balls made with oats, nut butter and banana or my popular baking recipes.

Please be reassured that you do not need to overhaul everything overnight. Replacing just one processed food each week with a real food alternative soon adds up. Over a couple of months, those small swaps can completely transform your child’s diet.

Round up

The link between ultra-processed foods and atopic conditions in children, including eczema, hay fever, asthma and food allergy is now supported by a substantial and growing body of research. The mechanisms centre on gut microbiome disruption, leaky gut and the resulting immune overactivity that drives allergic conditions. Remember this as the gut-skin or gut-lung connection.

This does not mean food is the only factor driving their inflammatory itching and wheezing, nor that changing diet will resolve every child’s issues overnight. But it does mean that what your child eats every day is one of the most powerful ways you have to help manage things better.

Remember to start small and swap one processed item for a real food alternative each week. These steps are not dramatic, but over weeks and months they shift the gut environment and with it, the immune environment in a positive direction.

If your child is struggling with persistent or complex allergies, eczema or asthma and you would like a more tailored assessment of their gut health, diet and nutritional status, get in touch with our NatureDoc clinical team. We work with you to build a practical health plan that fits your family’s life while making a proper difference to your child’s health.

Are UPFs making your child’s allergies, eczema and asthma worse?