Adverse reactions to wheat and gluten

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Adverse reactions to wheat and gluten

Harris Steinman and Karen du Plessis

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

The body's different mechanisms of defence involved in each type of adverse reaction to wheat cause symptoms which may be quite different from or confusingly similar to each other. The severity of symptoms can vary considerably within each type of adverse reaction, but the patterns are distinct. An allergy can cause very mild to quite severe reactions (such as life-threatening anaphylaxis), compared to wheat intolerance, which can cause significant discomfort, but is never dangerous. CD can lead to serious long-term complications if left untreated (discussed below).

Wheat allergy may be present in the absence of a family history, but CD is probably always inherited. However, as CD can be silent or latent, a family history is not always reliable.

About the proteins / allergens in wheat

Wheat, like all other foods, contains a number of proteins (more than 100), including albumin, globulin, gliadin and glutenin (gliadin and glutenin together form gluten). A person can be allergic to one or more of these proteins. The majority of allergies to wheat involve the albumin and globulin fractions, but gluten may also, rarely, cause allergic reactions.

Gluten is composed of two protein groups, namely gliadins, which give wheat dough its flow characteristics, and glutenins, which provide the elasticity in finished wheat products. Gliadin is a type of prolamin (a group of proteins with similar protein structures). Other grains such as rye and barley each contain their own prolamins, which cause the same intestinal damage in CD that gliadin causes. This is due to the similarity in protein structure. By definition, gluten is found only in wheat, although the term is commonly used to refer to any similar prolamin protein in any grain that is harmful to a person with CD.

Because the type and proportion of prolamin proteins in grains vary, the kind of reaction (if any) they are likely to cause also varies. Corn, rice, other cereal grains such as sorghum, millet, teff, ragi and Job's tears as well as buckwheat, quinoa and amaranth can safely be ingested by a person with CD. Wheat, barley, rye, spelt and kamut, however, should be avoided in CD.

The safety of the ingestion of oats has been controversial for a while, but the consumption of oats has recently been proven to be safe. However, it should be considered that most commercial oat products contain wheat flour or gluten. Contamination of oats with wheat may occur due to the sharing of equipment in grain processing and the rotation of crops (wheat may be grown on the same field as oats were). Therefore, contamination may be the cause of adverse reactions to oats often reported by gluten-sensitive individuals.

A. Wheat intolerance

Intolerance does not involve the immune system, and the mechanisms responsible for wheat intolerance may be because of an enzyme deficiency or undigested food (as a result of one of many reasons), which result in bacterial fermentation in the colon, causing specific symptoms.

B. Wheat allergy

What is wheat allergy?

A wheat allergy involves an immune reaction in response to an allergen (usually a protein in wheat) that the body is exposed to. A person can be allergic to one or more of the proteins in wheat. If inflammatory mediators are released or their levels enhanced by mechanisms that are independent of the immune system, the reaction is due to an intolerance.

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 a relatively common allergy, but there are no accurate figures for prevalence. It is, however, more prevalent in certain groups: for example, wheat allergy is responsible for occupational asthma in up to 30% of individuals in the baking industry.

Wheat allergy is most common in young children, of which the majority will outgrow it within five years. This occurs more quickly if the wheat-containing food is completely avoided. Those who develop the allergy later in life will probably retain it.

What are the symptoms of wheat allergy?

Allergic reactions to wheat can be acute or delayed, occurring within minutes or a few hours after eating or inhaling wheat. The symptoms can involve the skin (urticaria, eczema, angioedema, atopic dermatitis), the gastrointestinal tract (abdominal cramps, nausea and vomiting) and the respiratory tract (asthma or allergic rhinitis). Wheat can cause Baker's asthma and has also been associated with wheat-dependent exercise-induced reactions (see below).

Baker's asthma: Contact with or inhalation of wheat flour proteins is one of the causes of baker's asthma (an occupational allergy), but allergens other than the wheat itself (e.g., storage mites, yeast and baking additives) may also be causes. Symptoms that may present include rhinitis, skin itching/rash, ocular symptoms (including tearing, itching and conjunctival injection), respiratory symptoms (including coughing, wheezing, shortness of breath and sputum production) and "grain fever".

Wheat-dependent exercise-induced reactions: Exercise within 3 hours of wheat consumption can induce an adverse reaction in susceptible individuals. In some cases, this can also occur when wheat is consumed directly after exercise. Typical symptoms experienced include asthma, urticaria, angioedema, dyspnoea, syncope and anaphylaxis.

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. 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 dietitian must supervise treatment. Wheat-allergic patients who have sensitivity to gluten should avoid other gluten-containing cereals.

C. Coeliac Disease (gluten-sensitive enteropathy)

What is Coeliac Disease?

CD is a hereditary disorder of the immune system. The ingestion of gluten leads to damage of the mucosa (lining) of the small intestine. This results in malabsorption of nutrients and vitamins such as proteins, carbohydrates, fats, vitamins, minerals, and, in some cases, water and bile salts. 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.

The disease is permanent, and damage to the small intestine will occur every time gluten is consumed, regardless whether symptoms are present or not. It has been reported that as little as 0.1 grams of ingested gluten can trigger symptoms.

The onset of noticeable symptoms of CD seems to be dependent on the following: exposure to wheat, as when an infant is weaned (introduction of solids); predisposition through family history; and some kind of "trigger" mechanism. Little is known about this "trigger" but suspected factors include physical or emotional stress, trauma such as surgery or pregnancy, over-exposure to wheat, viral infection, other diseases, and even antibiotics.

How common is Coeliac Disease?

CD is one of the most common life-long disorders in certain countries. CD is frequently under-diagnosed, particularly in adults, who may present with only subtle symptoms. In some countries the incidence is as high as 1 in 200 (Sweden).

As coeliac disease can be silent or latent, a family history is not always reliable. It primarily affects caucasians of northwestern European decent and rarely affects Africans, people of Mediterranean extraction or Asians. It affects twice as many females as males.

CD usually develops in childhood but can begin at any age. Typically the disease presents at the age of 6-24 months, after wheat has been introduced into the diet, and in early adult life (30's and 40's).

What are the symptoms of Coeliac Disease?

There is no typical set of symptoms. However, there are "classic" symptoms (diarrhoea, bloating, weight loss, anemia, chronic fatigue, bone pain, and muscle cramps), but CD frequently presents with other symptoms. In some cases only one symptom may be experienced (e.g., anemia, a run-down feeling, or behavioral problems) or the symptoms may occur intermittently.

In infants and young children: Symptoms usually arise after weaning and with the introduction of cereals into the diet. In children, gastrointestinal problems are more evident; they include abnormal stools (ranging from diarrhoea, to soft, bulky, clay-coloured, foul-smelling stools, to constipation), abdominal distension, abdominal pain, flatulence, nausea, vomiting and intestinal malabsorption. Children also present with irritability, apathy, loss of appetite, weight loss, poor weight gain, short stature, muscle wasting, hypotonia, general failure to thrive, poor school performance, bone and joint pains, and occasionally rickets.

It is not uncommon for symptoms experienced during infancy to disappear during later childhood or adolescence, and then to reappear later in life. The disease does not disappear; the small intestine damage still occurs during these years even though no symptoms are experienced.

In older children and adults: The symptoms may be quite varied, from severe weight loss, diarrhoea and bulky, offensive stools to less severe symptoms that may lead to a missed diagnosis. Subtle complaints of abdominal bloating, cramping, flatulence and constipation are often mistakenly attributed to irritable bowel syndrome. Symptoms such as recurrent mouth ulceration, miscarriages or failure to conceive may lead to further investigations with an eventual diagnosis.

Some individuals present with only anemia-related fatigue and have no gastrointestinal symptoms. Other manifestations of the disease include osteopenic bone disease, infertility, tetany, ataxia and neurologic disorders.

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 CD must be confirmed by this biopsy. The procedure is safe and usually performed at the time of gastrointestinal endoscopy. However, it must me kept in mind that if the patient is on a gluten-free diet, the results of these tests are likely to be negative.

What is dermatitis herpetiformis?

Dermatitis herpetiformis is a form of CD. It is a skin reaction to gluten (granular IgA is deposited under the skin). Dermatitis herpetiformis manifests as a blistering, burning, itchy rash on the extensor surfaces of the body (mainly the back, sacrum, face, trunk, elbows, knees and buttocks, but also inside the mouth) in strikingly symmetrical patterns. In most of these individuals, intestinal biopsies are characteristic of CD regardless of whether gastrointestinal symptoms are present. The treatment is the same as for CD, but it may take two or more years after the initiation of the diet before the rash clears.

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, 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, folate, phosphorus and molybdenum). It is therefore essential that patients be managed in collaboration with a dietitian. Information on gluten-free diets is becoming increasingly available worldwide. Gluten-free products are also becoming more abundant and more easily available.

More information:

Article by Harris Steinman MBChB, DCh, DipAvMed, IMM and
Karen du Plessis BSc Diet

For more information contact:

Carine Clarke

Email carine@factssa.com
Food and Allergy Consulting and Testing Services
P.O. Box 565
Milnerton7435
Telephone: +27 (0) 21 551 2993
Fax: +27 (0) 21 551 2807

This article is an updated version of an earlier article at Science in Africa, Wheat, Gluten Allergy, Gluten Intolerance and Gluten Enteropathy

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