Food Hypersensitivity Flashcards
Food allergy
Involves immune system
IgE, non-IgE, mixed
Food intolerance
Doesn’t involve the immune system
Lactose
Vaso-active amines
Food additives
Immune response
Innate
Adaptive
IgE mediated
Involve production of Th2 cells
- switches IgM -> IgE
IgE antibodies attach themselves to surfaces of mass cells and basophils
If allergen binds successfully to IgE antibodies -> reaction
Non-IgE
Involves T-cells + other inflammatory cells
T-cells become sensitised on initial exposure + on repeated exposure cytokines released leading to inflammation
Reactions often delayed
Pollen Food Allergy
Pruitus
Mild oedema
Food Allergy testing
Skin prick test
Blood test
Food challenges
Food exclusion + reintroduction
Patch test
Contact dermatitis
Positive result doesn’t always mean pt allergic
Sensitivity + specificity low
Diagnosis
IgE mediated - skin prick, serum specific IgE, food exclusion + challenge
Non-IgE mediated - patch testing, serum antibodies
Jejunal biopsy, food exclusion + challenge
Food intolerance - FODMAP, H breath test, food exclusion + challenge
Elimination diet
Based on clinical history + adjunct allergy testing
Usually 2-4 weeks (no more than necessary)
Supervision of health care professional
Food + symptom diary
If improvements do not occur - check if following correctly
Single food exclusion
All sources of a single food
Multiple food exclusion
Foods most commonly associated with a disorder avoided (e.g. milk + egg for eczema)
2-3 weeks
Food reintroduced singly + gradually
Few foods diet (oligoallergenic)
Used when simpet avenues fail or when patient excluding many foods and this needs to be tested objectively
Oral challenge test
Gold standard
Home or hospital
May be open or blind (disguised)
Labial challenge
Starting dose half that reported to cause reaction
8-10g dry/100ml liquid/200g solid wet food
Final dose should equate to standard portion of that food
