Wheat, Gluten Allergy, Gluten Intolerance and Gluten Enteropathy

Dr Harris Steinman

Many articles about gluten intolerance have recently appeared. These have resulted in much unnecessary alarm and confusion among the public, and the adoption of pointless and even harmful diets.

What is gluten?

Gluten is the elastic, rubbery protein present in wheat, rye, barley and to a lesser degree in oats. It binds the dough in foods such as bread and other baked goods. It contributes to spongy consistency. Rice and maize do not contain gluten.

However, gluten is only one protein found in wheat, rye and barley. These foods, like all other foods, contain a number of discreet proteins that all can result in adverse reactions, including allergies.

For example, wheat protein comprises 4 main groups of proteins: water-soluble, salt-soluble, alcohol-soluble and alcohol-insoluble. The major proteins in wheat-albumin, globulin, gliadin and glutenin (gluten)-vary in proportion according to the type of wheat.

What types of adverse reactions are possible?

Adverse reactions to wheat, as to any food, can be allergic (in this case, wheat allergy), intolerance (in this case, wheat intolerance, gluten intolerance, and Coeliac disease), or due to other naturally occurring constituents.

Different mechanisms cause different adverse reactions. The resulting symptoms may be quite different from or confusingly similar to each other. The human body is able to mount a variety of defence mechanisms against proteins it regards as foreign or harmful. Scientists do not clearly understand why food proteins are regarded as harmful by the body, or how adverse affects occur. For example, wheat-sensitive allergic individuals typically produce IgE antibodies to the soluble grain proteins, but some develop gluten-specific IgE antibodies. Patients with Coeliac Disease develop gliadin-specific IgA and IgG antibodies.

1. Wheat allergy

What is wheat allergy?

Wheat allergy refers specifically to adverse reactions involving immunoglobulin E (IgE) antibodies to one or more protein fractions of wheat, including albumin, globulin, gliadin and glutenin (gluten). The majority of IgE-mediated reactions to wheat involve the albumin and globulin fractions. Gliadin and gluten may also, rarely, induce IgE-mediated reactions. Allergy to wheat may occur in any individual, unlike Coeliac Disease, which is hereditary.

Allergic reactions to wheat may be caused by ingestion of wheat-containing foods or by inhalation of flour containing wheat (Baker's asthma).

How common is wheat allergy?

Clinical experience suggests that wheat allergy is relatively uncommon, but there are no accurate figures for prevalence. The allergy is more prevalent in certain groups: e.g., wheat allergy is responsible for occupational asthma in up to 30% of individuals in the baking industry.

What are the symptoms of wheat allergy?

Allergic reactions to wheat (IgE-antibody mediated) usually begins within minutes or a few hours after eating or inhaling wheat. The more common symptoms involve the skin (urticaria [hives], eczema, angioedema [swelling due to allergy]), the gastrointestinal tract (abdominal cramps, nausea and vomiting, oral allergy syndrome) and the respiratory tract (asthma or allergic rhinitis). In association with exercise, reactions to gliadin or gluten can cause urticaria, angioedema or life-threatening anaphylaxis. As these proteins are present in other cereals, these symptoms may also occur in wheat-allergic individuals due to cross-reactivity.

How is wheat-allergy diagnosed?

The diagnosis may be easy if a person has the same reaction repeatedly after eating wheat-containing food. More often the diagnosis is difficult because wheat is usually consumed with other food. Diagnosis usually entails clinical evaluation (medical history, family history, food history) supported by appropriate laboratory tests (CAP® RAST blood tests, skin prick-testing). An elimination-challenge test may be employed to make the diagnosis.

How is wheat allergy treated?

Medication is ineffective in treating this condition. Avoidance of wheat and wheat-containing foods is the only treatment. (See Table below.) This may be difficult to maintain, particularly as wheat protein may be "hidden" in other foods. Rice or maize may be substituted as alternative cereals. A dietician must supervise treatment. Wheat-allergic patients who have sensitivity to gluten (or gliadin) should avoid other gluten-containing cereals.

Prognosis

The majority of young children with wheat allergy will outgrow it. Individuals who develop the allergy later in life will probably retain it. There is some evidence that individuals who remove wheat from their diet for a year or longer may be able to tolerate wheat upon re-introduction.

Label ingredients that indicate the presence of wheat proteins
Bread crumbs Bran Cereal extract Couscous Cracker meal Enriched flour Gluten High-gluten flour, high-protein flour Semolina wheat Vital gluten	Wheat bran, wheat germ, wheat gluten, wheat malt, wheat starch Whole wheat flour Gelatinized starch Hydrolyzed vegetable protein Modified food starch, modified starch Natural flavoring Soy sauce Starch Vegetable gum, vegetable starch

2. Gluten Intolerance (Gluten Enteropathy, Coeliac Disease)

What is Coeliac Disease?

Coeliac Disease (CD), also called Gluten Enteropathy, has until recently been known as Gluten Intolerance. CD is a hereditary disorder of the immune system in which eating gluten leads to damage of the mucosa (lining) of the small intestine (small gut). This results in malabsorption of nutrients and vitamins. CD is the result of IgA and IgG antibody responses to gluten. It is important to differentiate between CD, mediated by IgA and IgG antibodies, and wheat allergy, which is mediated by IgE antibodies.

How common is Coeliac Disease?

Coeliac Disease is one of the commonest life-long disorders in Western countries. CD is frequently under-diagnosed, particularly in adults, who may present with subtle symptoms. In some countries the incidence is as high as 1 in 200 (Sweden) or 1 in 10,000 (Denmark). The incidence in South Africa has not been ascertained, but is thought to be low, although the disease is most probably under-diagnosed.

What are the symptoms of Coeliac Disease?

Typically CD presents at the age of 6-24 months with symptoms of intestinal malabsorption, impaired growth, abnormal stools, abdominal distension, muscle wasting, poor muscle tone (hypotonia), poor appetite or irritability, following the introduction of cereals into the diet. In adults, the symptoms of CD may be quite varied, from severe weight loss and diarrhoea and bulky, offensive stools to subtle complaints of cramps, abdominal bloating, flatulence and even constipation. These individuals are often mistakenly diagnosed as having Irritable Bowel Syndrome. Recent studies show that some individuals with CD present with no symptom but a form of ataxia. Recurrent oral aphthous ulcers are common and should arouse suspicion of the condition. Other symptoms may include persistent iron-deficiency anaemia, folate deficiency anaemia or a calcium metabolism disturbance.

Dermatitis herpetiformis is a variant of Coeliac Disease in which clusters of itchy blisters occur, usually over the buttocks, knees and elbows.

How is Coeliac Disease diagnosed?

Doctors must have a low threshold of suspicion when seeing patients with symptoms such as those described above.

There are various blood tests that can be used to support the diagnosis of CD.

1. The anti-gliadin antibody (AGA) assay, which measures the amount of IgA and IgG antibody produced against the gliadin component of cereals
2. The anti-reticulin antibody (ARA) test, in which IgG antibodies are viewed in an immuno-fluorescent microscope examination
3. The anti-endomysial antibody (AEA) assay, which identifies IgA antibodies against the endomysium tissue.

These tests offer simple and fast tools to investigate patients with suspected CD. They are particularly recommended for screening relatives of CD patients or patients who are affected by a related disease such as Malabsorption or Diabetes Mellitus, and for monitoring the compliance to a gluten-free diet.

None of these tests has shown 100% accuracy, and a small-intestinal mucosal biopsy remains the cornerstone for diagnosis. Any provisional diagnosis of Coeliac Disease must be confirmed by this biopsy. The procedure is safe and usually performed at the time of gastrointestinal endoscopy.

Treatment of Coeliac Disease

Medication is ineffective in treating this condition. The only treatment available is the complete removal of gluten from the diet. This usually entails life-long avoidance of all cereals containing gluten, including wheat, oats, rye and barley. Individuals on any avoidance diet are at risk of developing deficiencies of micro-nutrients (e.g., thiamine, riboflavin, niacin, iron, selenium, chromium, magnesium, folacin, phosphorus and molybdenum). It is therefore essential that patients be managed in collaboration with a dietician. Information on gluten-free diets is becoming increasingly available worldwide. Gluten-free products are also becoming more abundant and more easily available.

Prognosis

CD is a life long disease.

3. Conclusion

A variety of reactions to proteins in cereals is possible. These include allergy and Coeliac disease. Adverse reactions may be mild to life-threatening, short-term to life-long. A correct diagnosis must be made as the treatment, dietary avoidance, is often very difficult and if incorrectly applied can lead to vitamin deficiencies or malnutrition. In young children, a wheat-free or gluten-free diet may result in poor social skills, as these children cannot participate equally at events such as parties. It is thus imperative that a definite diagnosis be made rather than a fad followed.

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