Wheat allergy and intolerance: The facts

Published: 21 January 2008

To coincide with Food Allergy and Intolerance Week (21 - 25 January), the factsheet below will help to clarify the facts on wheat allergy and intolerance. If we can help with any queries, please call the Flour Advisory Bureau on 020 7493 2521.

. The difference between wheat intolerance and wheat allergy.
Despite the confusion between food allergies and food intolerance, there are clear differences between the two.  Food allergies involve a specific immune response, while food intolerances do not.

A food allergy involves an abnormal immune response to a protein in a food.  The immune system responds by producing antibodies such as immunoglobulins, of which there are several types.  The change in the blood concentration of immunoglobulins can be detected by a simple blood test. True wheat allergy is extremely rare and it is estimated that only 0.1% of the population are allergic to wheat protein. This excludes those with coeliac disease, an allergy to the gluten fraction of wheat protein that requires a formal diagnosis and a lifelong gluten free diet.

Coeliac UK estimates that there are approximately 125,000 people who have been diagnosed with coeliac disease (www.coeliac.co.uk).

It is caused when the body produces antibodies that attack its own tissues in the presence of gluten, a protein fraction found in wheat, rye and barley. A protein similar to gluten is also found in oats.  Research has suggested more people may have coeliac disease than are actually diagnosed.

. A food intolerance is any form of food sensitivity or food reaction that does not involve the immune system.  Intolerance may be a result of a reaction to naturally occurring chemicals in a food, such as a histamine rash to strawberries. Chemicals added to the food may also cause intolerance in some people, such as the benzoates or sulphites added as preservatives. Other forms of food intolerance are related to problems with food digestion such as lactose intolerance where the enzyme needed to digest lactose in milk is deficient in sufferers, causing bloating and sometimes diarrhoea if excessive lactose is taken.  Idiosyncratic reactions occur via unknown mechanisms. Wheat intolerance is an undefined condition.  Unfortunately there is no solid medical or scientific evidence about the condition and its causes. Therefore it is less easy to diagnose and the causes are unknown.  Symptoms attributed to wheat intolerance are very similar to the symptoms for a number of other conditions such as stress, IBS  - or even a good night out.

. Wheat's ranking in the list of foods that cause adverse reactions.
It is generally accepted that wheat is not a major cause of adverse reactions to food.  A review of published scientific papers puts wheat 8th in a list of foods likely to cause an allergic reaction - behind egg, peanut, milk, soya, nuts, shellfish and fish.

Adverse reactions to foods may be due to food allergy or food intolerance. While about one in three people believe they are "allergic" to certain foods, the true prevalence of food allergy is only about 2% of the adult population. In children, the incidence is higher at 3-7% although the majority of children outgrow food allergies by the time they start school.
  http://www.eufic.org/article/en/health-lifestyle/food-allergy-intolerance/expid/basics-food-allergy-intolerance/

Various government and medical association statistics project the expected incidence to be between one in 25 and one in 70 (a range of 1.4% to 4% of the adult population).
http://www.just-food.com/store/product.aspx?id=32627&lk=rap

. Perception versus reality: prevalence.
*Studies have shown that 20% of adults and 28% of parents suspect that they, or their children, suffer from an adverse reaction to food but when actually tested using double blind placebo controlled studies (the gold standard of testing) (DBPCS) only 1.5% of adults were found to suffer from any reaction to the suspect food and only 0.1% reacted adversely to wheat.  A survey by the Grain Information Service (2005) revealed that the main causes of bloating were monthly female hormone fluctuations (32%), over-eating/irregular meal patterns (28%) and stress related indigestion (27%) rather than an adverse reaction to foods.

. Perception versus reality: wheat consumption.
Reports claim we're becoming more intolerant to wheat because we consume more now than in the past. In reality we're not consuming more wheat now than in the past.  In fact, bread consumption has declined dramatically since the war and flour production has remained relatively static. However when we eat wheat, we eat larger portions.  For example a lunchtime panini contains more bread per serving than two medium slices of bread.  Intolerance symptoms are usually dose related, so larger portion sizes appear to be a major contributory factor to intolerance. There is evidence to suggest that as with allergies in general, adverse reactions to food are on the increase.  However, there are also indications that this increase is linked somehow to our better standard of living.  Until further evidence is available we must be cautious about laying the blame for the increase in adverse reactions to food on food itself.

. The importance of a proper medical diagnosis.
It's extremely important for individuals who think they may have an adverse reaction to wheat visit their doctor.  GPs can exclude medical conditions with similar symptoms, allergies and give advice on safe dietary changes.  According to the British Dietetic Association (www.BDA.uk.com), the three most reliable tests for a true allergy are an IgE antibody blood test; a skin prick test or a patch test.  The BDA advises against other allergy tests such as Vega Testing, Applied Kinesiology or hair sample analysis which it regards as unsound methods of diagnosis.   GPs believe that the trend of 'self-diagnosing' and making uninformed dietary changes can lead to problems such as nutrient deficiency, osteoporosis, and immune problems.

Elimination diets should only be attempted under the supervision of a Registered Dietician (RD).  It's essential that wheat in the diet is replaced with foods of equivalent nutritional value.  In addition, elimination diets work on the premise that the 'culprit' food is reintroduced gradually after a short period of exclusion, to confirm the suspicion of specific food intolerances.  Articles and books that advocate wheat free diets are commonly written by self-styled nutritionists or therapists and their information should be treated with caution.

*Bock, S.A et al., (1988). Double blind, placebo-controlled food challenge (DBPCFC) as an office procedure: a manual. Journal of Allergy and Clinical Immunology. 82, 986-997.

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