Food Intolerance Flashcards
Explain the Chinese restaurant syndrome.
Monosodium glutamate may provoke flushing, headache, and abdominal symptoms (the Chinese restaurant syndrome).
What are common allergic foods of children and adults?
Common allergenic foods include milk, eggs, and peanuts in children; and fish, shellfish, nuts (especially peanuts), and fruit in adults.
How is allergen testing carried out?
Skin prick testing.
What is the treatment for food allergy?
The only treatment for food allergy is avoidance of the offending food. Training patients to avoid a particular food often requires the help of a dietitian, clear written instructions, and advice about the labelling of foods.
Explain how patients may outgrow their food allergy and what this means clinically.
Many patients outgrow their clinical reactivity to a food (90% of infants allergic to milk do so by the age of 3, and half of patients who are allergic to eggs do so, but most patients allergic to peanuts or cod do not). The diagnosis should therefore be re-evaluated yearly.
Explain the use of adrenaline in food allergy.
Adrenaline is life saving in cases of anaphylaxis and should be administered as early as possible.
Should antihistamines be used in food allergic reactions/
Antihistamines are effective in relieving the symptoms of the oral allergy syndrome but may mask initial warning symptoms of a more severe reaction and should therefore not be used.
Define food intolerance.
Difficulty digesting foods which can lead to gastrointestinal discomfort.
Explain the difference between food allergy and food discomfort.
A true food allergy causes an immune system reaction that affects numerous organs in the body. It can cause a range of symptoms. In some cases, an allergic food reaction can be severe or life-threatening. In contrast, food intolerance symptoms are generally less serious and often limited to digestive problems.
Involving immune mechanisms = Allergy
What are the clinical symptoms of Celiacs disease?
Clinical features are diverse and include gastrointestinal symptoms, metabolic bone disease, infertility, and many other manifestations.
What is non-celiac gluten sensitivity?
Non-Celiac Gluten/Wheat Sensitivity. People with non-celiac wheat sensitivity experience symptoms similar to those of celiac disease, which resolve when gluten is removed from the diet. However, they do not test positive for celiac disease.
How do you approach diagnosing children with Celiac’s disease?
The major modes of presentation in children are recurrent abdominal pain, growth problems (failure to thrive and short stature), and the screening of high risk groups.
How do you approach diagnosing adults with Celiac’s disease?
Although diarrhea remains one mode of presentation that prompts testing for celiac disease in adults, most patients with the disease do not have diarrhea. Instead, most adults have one of the many “non-classic symptoms” such as anemia (usually as a result of iron deficiency, although it may be caused by chronic disease); osteoporosis; and various other presentations, including dermatitis herpetiformis, abdominal pain, neurological or psychiatric problems, infertility, aphthous stomatitis, and vitamin deficiencies.
Food allergy is mediated by which immunoglobulin and which immune cells?
IgE
T-cell mediated
Acute hypersensitivity
Acute hypersensitivity: An example is urticaria, vomiting or diarrhoea after eating nuts, strawberries or shellfish. These IgE-mediated reactions do not usually produce clinical problems, as the patients have already learned to avoid the suspected food. Inadvertent ingestion of the incriminating food can sometimes occur, leading to angioneurotic oedema.
Angioedema
Angioedema is an area of swelling of the lower layer of skin and tissue just under the skin or mucous membranes. The swelling may occur in the face, tongue, larynx, abdomen, or arms and legs. Often it is associated with hives, which are swelling within the upper skin.
Explain how some food allergies can exacerbate eczema / asthma?
Eczema and asthma: These tend to affect young children; they are often due to egg and are IgE-mediated.
Explain how food intolerance may bring upon a migraine.
Migraine . This sometimes follows the intake of foods such as chocolate, cheese and alcohol, which are rich in certain amines, such as tyramine.
Explain the aetiology of celiac’s disease.
Gluten is the entire protein content of the cereals wheat, barley and rye. Prolamins (gliadin from wheat, hordeins from barley, secalins from rye) are damaging factors. These proteins are resistant to digestion by pepsin and chymotrypsin and thus it remains in the intestinal lumen, triggering immune responses.
Why is gluten resistant to digestion by pepsin and chymotrypsin?
Because of it’s high glutamine and proline content.
Which region of the intestine is affected most intensely in Celiac’s disease?
The mucosa of the proximal small bowel is predominantly affected, the mucosal damage decreasing in severity towards the ileum as gluten is digested into smaller ‘non-toxic’ fragments.
Gluten is the protein content in wheat, barley and rye - what are the individual proteins in each?
Prolamins:
Gliadin from wheat.
Hordeins from barley.
Secalins from rye.
Explain the pathophysiology of Celiac’s disease.
Gliadin peptides then bind to antigen-presenting cells, which interact with CD4 + T cells in the lamina propria via HLA class II molecules DQ2 or DQ8. These T cells produce pro-inflammatory cytokines, particularly interferon-γ. CD4 + T cells also interact with B cells to produce endomysial and tissue transglutaminase antibodies. Gliadin peptides also cause release of IL-15 from enterocytes, activating intraepithelial lymphocytes with a natural killer cell marker. This inflammatory cascade releases metalloproteinases and other mediators, which contribute to the villous atrophy and crypt hyperplasia that are typical of the disease.
What are the HLA implicated in celiac’s disease?
DQ2 and DQ8
