Food Intolerance

Question 1

Explain the Chinese restaurant syndrome.

Answer 1

Monosodium glutamate may provoke flushing, headache, and abdominal symptoms (the Chinese restaurant syndrome).

Question 2

What are common allergic foods of children and adults?

Answer 2

Common allergenic foods include milk, eggs, and peanuts in children; and fish, shellfish, nuts (especially peanuts), and fruit in adults.

Question 3

How is allergen testing carried out?

Answer 3

Skin prick testing.

Question 4

What is the treatment for food allergy?

Answer 4

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.

Question 5

Explain how patients may outgrow their food allergy and what this means clinically.

Answer 5

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.

Question 6

Explain the use of adrenaline in food allergy.

Answer 6

Adrenaline is life saving in cases of anaphylaxis and should be administered as early as possible.

Question 7

Should antihistamines be used in food allergic reactions/

Answer 7

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.

Question 8

Define food intolerance.

Answer 8

Difficulty digesting foods which can lead to gastrointestinal discomfort.

Question 9

Explain the difference between food allergy and food discomfort.

Answer 9

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

Question 10

What are the clinical symptoms of Celiacs disease?

Answer 10

Clinical features are diverse and include gastrointestinal symptoms, metabolic bone disease, infertility, and many other manifestations.

Question 11

What is non-celiac gluten sensitivity?

Answer 11

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.

Question 12

How do you approach diagnosing children with Celiac’s disease?

Answer 12

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.

Question 13

How do you approach diagnosing adults with Celiac’s disease?

Answer 13

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.

Question 14

Food allergy is mediated by which immunoglobulin and which immune cells?

Answer 14

IgE

T-cell mediated

Question 15

Acute hypersensitivity

Answer 15

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.

Question 16

Angioedema

Answer 16

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.

Question 17

Explain how some food allergies can exacerbate eczema / asthma?

Answer 17

Eczema and asthma: These tend to affect young children; they are often due to egg and are IgE-mediated.

Question 18

Explain how food intolerance may bring upon a migraine.

Answer 18

Migraine . This sometimes follows the intake of foods such as chocolate, cheese and alcohol, which are rich in certain amines, such as tyramine.

Question 19

Explain the aetiology of celiac’s disease.

Answer 19

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.

Question 20

Why is gluten resistant to digestion by pepsin and chymotrypsin?

Answer 20

Because of it’s high glutamine and proline content.

Question 21

Which region of the intestine is affected most intensely in Celiac’s disease?

Answer 21

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.

Question 22

Gluten is the protein content in wheat, barley and rye - what are the individual proteins in each?

Answer 22

Prolamins:
Gliadin from wheat.
Hordeins from barley.
Secalins from rye.

Question 23

Explain the pathophysiology of Celiac’s disease.

Answer 23

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.

Question 24

What are the HLA implicated in celiac’s disease?

Answer 24

DQ2 and DQ8

Question 25

Symptoms of Celiac’s disease:

Answer 25

Non-specific; they include tiredness and malaise, often associated with anaemia.

Gastrointestinal symptoms may be absent or mild. Coeliac disease should be tested for in all patients with symptoms suggestive of irritable bowel syndrome. Diarrhoea or steatorrhoea, abdominal pain and weight loss suggest more severe disease. Mouth ulcers and angular stomatitis are frequent and can be intermittent. Infertility and neuropsychiatric symptoms of anxiety and depression occur.

Rare complications include tetany, osteomalacia or gross malnutrition with peripheral oedema. Neurological symptoms, such as paraesthesia, ataxia (due to cerebellar calcification), muscle weakness or a polyneuropathy occur; the prognosis for these symptoms is variable.

Question 26

What is a long term problem of celiac’s disease?

Answer 26

Long-term problems include osteoporosis, which occurs even in patients on long-term gluten-free diets.

Question 27

How is Celiac’s disease diagnosed?

Answer 27

Small bowel biopsy is still considered to be the ‘gold standard’ for positive diagnosis.

Question 28

How is intestinal histology affected in Celiac’s disease?

Answer 28

Villous atrophy
Crypt hyperplasia
Intraepithelial lymphocytes

Question 29

What are the indications for testing for Celiac’s disease?

Answer 29

Indications for testing include persistent diarrhoea, folate or iron deficiency, unexplained abnormal liver biochemistry, a family history of coeliac disease and associated autoimmune disease.

Question 30

What is the treatment for Celiac’s disease?

Answer 30

Gluten free diet.

Replacement minerals and vitamins , such as iron, folic acid, calcium and vitamin D, may be needed initially to replace body stores.

Question 31

What is a positive tTG IgA result?

Answer 31

tTG IgA antibody concentrations greater than 40 U/mL usually correlate with results of duodenal biopsies consistent with a diagnosis of celiac disease.

Question 32

tTG

• relevance in diagnosis?

Answer 32

A tissue transglutaminase IgA (tTg-IgA) test is used to help doctors diagnose celiac disease.

The immune system makes antibodies that attack an enzyme in the intestines called tissue transglutaminase (tTG).

Question 33

How is IBS (irritable bowel syndrome) characterised?

Answer 33

Irritable bowel syndrome (IBS) is characterised by recurrent abdominal pain in association with abnormal defecation and bloating.

Question 34

Rome III criteria for diagnosis of irritable bowel syndrome

Answer 34

Recurrent abdominal pain or discomfort on at least 3 days per month in the last 3 months, associated with two or more of the following:

• Improvement with defecation.
• Onset associated with a change in frequency of stool.
• Onset associated with a change in form (appearance) of stool.

Question 35

What conditions commonly coincide with IBS?

Answer 35

Psychiatric illness, such as anxiety, depression, somatisation and neurosis. Panic attacks are also common. Acute psychological stress and overt psychiatric disease are known to alter visceral perception and gastrointestinal motility.

Question 36

What are the treatment options for IBS?

Answer 36

FODMAPS diet

Anti-depressant medication

Question 37

FODMAP’s

Answer 37

Fermentable
Oligosaccharides
Disaccharides
Monosaccharides
And 
Polyols

Question 38

Examples of oligosaccharides:

Answer 38

FOS, GOS, raffinoses, malto-dextrin

Question 39

A common disaccharide:

Answer 39

Lactose

Question 40

A common monosaccharide:

Answer 40

Fructose

Question 41

Examples of polyols:

Answer 41

Sorbitol and Xylitol

Question 42

What is a low FODMAP’s diet thought to help and why?

Answer 42

Aids irritable bowel syndrome as promotes less gas production therefore reduced feeling of bloating and abdominal discomfort.

Question 43

What rash can coeliac’s disease cause?

Answer 43

For some people, celiac disease causes an itchy, blistering rash known as dermatitis herpetiformis. It may begin with an intense burning sensation around the elbows, knees, scalp, buttocks, and back. Clusters of red, itchy bumps form and then scab over.

Question 44

Which part of the small bowel is predominantly affected by coeliac disease?

Answer 44

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.

Question 45

What happens to the histology of the small bowel in coeliac disease?

Answer 45

There is hyperplasia of crypts, and atrophy of the villi thus the overall wall thickness remains stable, but the surface of the bowel becomes flattened -Increased number of inflammatory cells in lamina propria

Question 46

Pathogenesis of Coeliacs:

Answer 46

In coeliac disease, auto-antibodies are created in response to exposure to gluten that target the epithelial cells of the intestine and lead to inflammation. There are two antibodies to remember: anti-tissue transglutaminase (anti-TTG) and anti-endomysial (anti-EMA). These antibodies relate to disease activity and will rise with more active disease and may disappear with effective treatment.

Question 47

What region of the GI tract is most affected in coeliacs?

Answer 47

Inflammation affects the small bowel, particularly the jejunum. It causes atrophy of the intestinal villi. The intestinal cells have villi on them that help with absorbing nutrients from the food passing through the intestine. The inflammation causes malabsorption of nutrients and the symptoms of the disease.

Question 48

How can coeliacs present?

Answer 48

Failure to thrive in young children
Diarrhoea
Fatigue
Weight loss
Mouth ulcers
Anaemia secondary to iron, B12 or folate deficiency
Dermatitis herpetiformis (an itchy blistering skin rash typically on the abdomen)

Question 49

What condition is always test for coeliacs due to a common association?

Answer 49

Remember for your exams that we test all new cases of type 1 diabetes even if they don’t have symptoms as the conditions are often linked.

Question 50

What genes are commonly associated with coeliacs?

Answer 50

HLA-DQ2 gene (90%)

HLA-DQ8 gene`

Question 51

Note: Coeliacs is commonly associated with other autoimmune conditions:

Answer 51

Coeliac disease is associated with many other autoimmune conditions:

Type 1 Diabetes
Thyroid disease
Autoimmune hepatitis
Primary biliary cirrhosis
Primary sclerosing cholangitis

Question 52

Complications of Coeliacs:

Answer 52

Vitamin deficiency
Anaemia
Osteoporosis
Ulcerative jejunitis
Enteropathy-associated T-cell lymphoma (EATL) of the intestine
Non-Hodgkin lymphoma (NHL)
Small bowel adenocarcinoma (rare)