Can eczema be triggered by ingested food?

Food-Induced Eczema: Relationship Between Ingested Food and Eczema Flares

Yes, eczema (atopic dermatitis) can be triggered by ingested food, particularly in children with moderate to severe disease, though this occurs less frequently in adults. 1

Prevalence and Clinical Significance

• Food allergies are present in a fair number of children with atopic dermatitis (AD) and a much smaller percentage of adult patients, with higher prevalence in those with younger age and more severe disease 1
• Studies have revealed that more than 50% of affected children with AD that can be exacerbated by certain foods will react with a worsening of skin eczema either alone or in addition to immediate symptoms 2
• The reported prevalence of food allergy in adult patients with eczema is lower (approximately 10%), but more than half of these will show immunological evidence supporting their clinical history 3

Mechanisms of Food-Induced Eczema

• Food-induced allergic reactions may be mediated by:
  • IgE mechanisms only (typically immediate reactions)
  • Non-IgE-mediated mechanisms only (typically delayed reactions)
  • Both IgE- and non-IgE-mediated mechanisms 1
• Eczematous reactions to food can occur as:
  • Immediate reactions (within minutes to a few hours)
  • Delayed reactions (within several hours to a few days) 1
• Clinical studies show that food can directly provoke flares of atopic dermatitis, particularly in sensitized infants 2

Common Food Triggers

• In children:
  • Milk, egg, and peanut account for the vast majority of allergic reactions in young children 1
  • These "classical" food allergens are most common in childhood 4
• In adolescents and adults:
  • Peanut, tree nuts, and seafood (fish and crustacean shellfish) are more common 1
  • Pollen-related foods become more relevant in older children, adolescents, and adults 1, 2
• Nuts and tomatoes have been identified as major allergens in some adult populations with eczema 3

Diagnostic Approach

• A true food allergy requires reproducible clinical symptoms or signs after food exposure/ingestion 1
• Broad panel allergy testing independent of a history of reaction to foods is not recommended 1
• The National Institute of Allergy and Infectious Diseases (NIAID) suggests consideration of limited food allergy testing if a child less than 5 years of age has moderate to severe AD and:
  • Persistent disease despite optimized management and topical therapy
  • A reliable history of an immediate allergic reaction after ingestion of a specific food
  • Or both 1
• Diagnostic methods include:
  • Skin prick testing (SPT) - an in vivo test that assesses immediate/type I hypersensitivity reactions 1
  • Food-specific IgE levels measured in serum (such as radioallergosorbent testing or immunoCAP testing) 1
  • Oral food challenges - often necessary to confirm clinical relevance of sensitization 2

Common Pitfalls in Diagnosis

• Up to 35% of individuals reporting a reaction to food believe they have food allergy, whereas studies confirming food allergy by oral food challenge suggest a much lower prevalence of about 3.5% 1
• Positive allergy tests may reflect sensitization (associated with IgE reactivity) but have poor correlation with clinical allergic responses 1
• In children with AD, eczematous flares erroneously attributed to foods are sometimes precipitated by:
  • Irritants
  • Humidity
  • Temperature fluctuations
  • Bacterial infections of the skin (e.g., Staphylococcus aureus) 1
• Unnecessary diets not based on proper diagnosis may lead to malnutrition and additional psychological stress 2

Management Considerations

• Food-induced eczema should be diagnosed only by a thorough diagnostic procedure that considers:
  • Patient's history
  • Degree of sensitization
  • Clinical relevance of the sensitization (often proven by oral food challenges) 2
• When evaluating food triggers in eczema, it's important to assess the skin with an established score (e.g., SCORAD, EASI) after 24 hours and later, as otherwise worsening of eczema will be missed 2
• Most patients react only to one or two food items, and these often differ from one patient to another, making undirected exclusion diet regimens unnecessary and potentially harmful 5
• Dietary recommendations in atopic eczema should be based on careful allergological workup of the individual patient to avoid risks of malnutrition and anaphylactic reactions 5