Allergies Flashcards
(24 cards)
What are the 14 food allergens
- gluten
- milk
- eggs
- mustard
- peanuts
- tree nuts
- soya
- celery
- lupin
- sulphites
- mollusks
- fish
- crustaceans
- sesame
What are conditions that may be caused by a reaction to food.
- vomiting
- wheeze/asthma
- anaphylaxis
- growth faltering/weight loss
- angio-oedema
-rash - diarrhoea/constipation.
What are some considerations when it comes to allergies.
Children vs adults - certain food groups such as milk is a staple part of a childs diet for growth and development
mild vs severe
medication vs diet
What is eosinophilic oesphagitis
A build-up of eosinophils in the esophagus, causing inflammation. It can cause various symptoms such as difficulty swallowing. Many people with EoE are atopic - have symptoms of one or more allergic disorder such as asthma or food allergy.
What is an IgE mediated allergy
This is the classical food allergy where reactions occur quickly after exposure and can be life threatening. IgE antibodies and mast cells release chemicals such as histamine and other inflammatory mediators.
What are non IgE mediated food allergies
Involves other components of the immune system. Onset of symptoms is usually slower and relate to reactions in the GI tract such as vomiting, bloating diarrhea. Common causative non-IgE mediated food allergies in infants is cows milk and soy proteins and wheat in children. It can cause colic in babies and IBS or constipation in adults.
What are non-immune mediated food hypersensitivity
These reactions usually occur due to enzyme deficiencies such as lactase, pharmacological agents such as caffeine and toxicants such as spoilt food.
Explain pharmacological agents and non-immune mediated food hypersensitivity
Many foods and beverages contain substances that are pharma logically active. Large intakes or sensitivity to these substances can cause symptoms such as migraines, tremors, palpitations and sweating . e.g. include caffeine, histamine and tyramine.
What foods are tyramine and histamine present in
Strong cheeses, red wine, spinach, aubergine, tuna, mackerel .
Explain chemical intolerance and non-immune mediated food hypersensitivity
reactions can occur to both natural and artificial chemicals and examples include food colorings, sulphites and benzoates.
There is variation in the speed of symptom onset and reactions usually last a few hours.
What is the threshold to chemical agents
Some people can tolerate small amounts but a single large dose can trigger symptoms. Can also have symptoms due to a build-up or a combined nature.
What are the clinical features of a reaction to chemicals.
abdominal discomfort, nausea, vomiting, itching, angiooedema.
Give examples of enzyme deficiencies and non-immune mediated food hypersensitivity
galactosemia (affects the bodies ability to convert galactose into glucose), PKU, disaccharide deficiency (lactase, sucrase and threlase in mushrooms (causes immediate vomiting)
Explain toxic reactions to foods.
Naturally occuring toxins in foods can mimic an allergic reaction e.g. histamine in spoilt fish and saxitoxins in clams and oysters.
Diagnosis - explain the skin prick test.
A small amount of allergen extract is placed on the skin and the skin is then pricked to allow the allergen enter. If the person is allergic, a raised, itchy red num appears with 10-15 minutes.
Diagnosis - blood tests
Measure the levels of IgE antibodies to various allergens in the bllod
clinical assessment - diagnosis
Allergy focused diet history - listen to the patients account of their symptoms
What should you ask during a diet history
Foods currently being eaten and avoid
Known food reactions, including what was eaten the and length of time between consumption and symptoms
what are the symptoms
frequency and severity of symptoms
quantity of food that elicted a reaction
family history
effectiveness of previous symptoms.
Explain the different elimination diets that can be used.
Single food exclusion diet (egg or milk)
multiple food exclusion diet (milk and egg for eczema, milk and soya for non-immune mediated IG or milk, egg, soya and wheat for EOE), go fishing diet.
Explain the reintroduction of foods.
Try one new food at a time. Start with small amount of the food and slowly increase to normal quantities over 2-4 days. For suspected quick onset of symptoms or severe reactions, food may need to be reintroduced in the hospital.
What is the milk ladder
It is suitable for non-IgE mediated cows milk allergy and is based on the principle that processing and heating milk reduces allergenicity
What is the issue when it comes to dietary avoidance.
The restriction of food can increase the risk of dietary imbalance, especially if the problem food is a major contributor to nutrient intake
What is the dietitians role in exclusion diets
- Provide food alternatives if the avoided food is a staple
- Ensure the diet is nutritionally adequate e.g. consider Ca, protein and iodine if avoiding milk
- explain food labeling laws include precautionary allergen labeling - it is essential that someone with an allergy checks the ingredients and considered reformulations of products.
- discuss high risk situations.
