There has been a lot of research carried out into the relationship between diet and atopic dermatitis, it is understood that diet can play a factor in the development of the condition and as a trigger of flares. Overall there is no consensus on the relationship between diet and AD and therefore there are no specific rules to follow. Below is a summary of the current understanding.

The impact of our diet on our body is complex and best understood when broken down into separate components. 

1. Food allergies

2. Food intolerances

3. Supplements that interact with the disease process

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1. Food allergies

The relationship between food allergies (FA) and AD is complex, in summary, food allergies mainly provoke atopic dermatitis in early childhood, not adulthood and people should be wary of eliminating foods from their diet without robust evidence of allergy.

Both FAs and AD are atopic (allergy-related) conditions and often co-exist., There is evidence to suggest that AD in early childhood can facilitate the development of FAs due to the weakened skin barrier function seen in AD which allows food allergens to penetrate the skin leading to sensitisation. Not all individuals who have been sensitised to food allergens will go on to develop symptomatic food allergies (reactions to further exposure).

For those that do develop FAs re-exposes can trigger a broad range of symptoms from breathing issues (wheeziness), bowel problems (diarrhoea) or skin reactions (lip swelling, itchiness, flares of eczema). The timing of these reactions varies and broadly falls into two categories, immediate or delayed. 

Some individuals with FAs will experience AD flares following exposure to the allergen, this is a delayed-type reaction and typically occurs 6-48 hrs after exposure. This pattern of FAs and AD flares is much stronger/clearer in young children than in adults, most adults sensitised to foods will not experience AD flares following exposure. 

In young children with severe AD or those whose skin does not respond to treatment, screening for allergens which have a known association with provoking flares such as cow’s milk and egg is recommended.

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2. Food intolerances

Food intolerances are much more common than allergies and cover a broad range of symptoms that can occur due to exposure to foods, often this is due to issues with gut bacteria or enzyme deficiencies. These are harder to define as often there is no simple blood test to confirm or exclude the intolerance. Symptoms of food intolerance can also manifest in many different symptoms including exacerbation of underlying skin problems. 

Rather than go into detail about food intolerances we’ve summarised the nutritional supplements that have been shown to impact eczema.

Role of probiotics

Probiotics are live bacteria (friendly bacteria) that aid food digestion by actively breaking down foods. These can be taken either as supplements or by increasing dietary consumption of foods containing naturally high levels of probiotic bacteria (kimchi, miso, coconut kefir). The data on the benefit of these is inconclusive but some studies have shown improved eczema symptoms by increasing probiotic intake. 

‍Role of prebiotics

Prebiotics are food supplements that are specifically chosen to increase the growth of our natural gut bacteria (think of them as bacteria boosters). Eating these supplements creates a nutrient-rich environment allowing our natural bacteria to thrive, this is thought to provide allergy-protective effects. Examples include asparagus, bananas, onions, leeks and leafy greens. 

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3. Supplements that interact with the disease process

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Essential fatty acids

Omega-3 has been shown to be beneficial in suppressing inflammation. There is mixed evidence to support its benefit in atopic dermatitis but some studies have shown reduced itchiness and condition severity. 

Vitamins D

Vitamin D’s main role in the body is to help the body store calcium but it is also known to have a role in preventing infections and can suppress immune reactions in the skin. Both vitamin D deficiency and AD are more common in populations who live further away from the equator suggesting a possible relationship between low vitamin D levels and AD. There is conflicting evidence on the benefit of vitamin D supplements with some research showing improvement in disease severity with supplements. This is likely to only be of benefit to those who are vitamin D deficient (risk factors include: dark skin, higher BMI, and reduced sun exposure). If you think you could be vitamin D deficient your GP should be able to arrange a blood test to check your levels.