                           VegSocUK Information Sheet
                             THE VEGETARIAN SOCIETY

                           FOOD ALLERGY & INTOLERANCE

   Food allergy is often mistaken for food intolerance. It is important to note
   that allergy is only one of a number of possible reasons for food
   intolerance.

   Food intolerance can be defined as a condition where particular adverse
   effects occur after eating a particular food or food ingredient. Genuine food
   intolerance is different from psychologically based food aversion, where a
   person strongly dislikes a food and believes that a food produces a
   particular reaction.

   A genuine food allergy is when a specific immune reaction occurs in the body
   in response to consuming a particular food. Allergies often run in families,
   and people who are allergic to some foods may also be allergic to other
   environmental factors, such as house dust, animal fur and pollen.

   A true allergic response involves an altered or abnormal tissue reaction to
   an antigen. An antigen can be a protein, a substance bound to a protein, a
   food additive or less commonly, a polysaccharide. The antigen combines with
   an antibody and produces an immune response, which results in cell damage and
   the release of histamine. The immune system plays an essential role in our
   bodies in protecting us from the invasion of harmful substances. An allergy
   occurs when the mechanism operates inappropriately in response to a harmless
   substance such as a particular food protein.

   Food intolerances, other than allergies, can occur for a variety of reasons
   including;

    Non allergic histamine release

   The signs are very similar to an allergy and include headache, swelling,
   urticaria, vomiting and diarrhoea. A substance called histamine is released
   (it is also released in true allergic reactions) in response to foods such as
   shellfish or strawberries.

    Metabolic defects

   A lack or deficiency of enzymes responsible for the digestion of food can
   cause many types of food intolerance. For example, a deficiency in lactase,
   the enzyme responsible for digesting milk, causes intolerance to milk.

   Coeliac disease is a gut intolerance to a protein found in wheat, called
   gluten, it would not be considered an allergy. The symptoms of coeliac
   disease are controlled by following a gluten-free diet. It is unknown exactly
   why or how gluten harms the gut, although it is now thought to be an abnormal
   immunological response rather than an enzyme deficiency. It is still not
   considered to be a food allergy in the true sense of the definition (see
   Gluten-free Diet infosheet).

    Pharmacological effects

   Some food substances can act like drugs, particularly if taken in large
   quantities. The most familiar of these substances is caffeine, found in tea,
   coffee, chocolate and cola drinks. A large intake of caffeine can cause
   tremor, migraine and palpitations. Other pharmacologically active substances
   found in food include histamine, tyramine, tryptamine and serotonin, which
   may be consumed in foods such as red wine, cheese, yeast extract, avocados
   and bananas. In susceptible people, these foods can trigger urticaria, facial
   flushing and headaches.

    Food intolerance of unknown origin

   Reactions can be provoked by many foods and food products which we cannot be
   clear about. They may or may not be allergic reactions. Food additives,
   particularly tartrazine and sodium benzoate, can provoke urticaria, rhinitis
   and asthma. Yeasts can provoke a number of reactions in some people,
   particularly skin disorders.
   ___________________________________

  COMMON CAUSES OF FOOD INTOLERANCE

   The most common food intolerances, in order of frequency are milk, eggs,
   nuts, fish/shellfish, wheat/flour, chocolate, artificial colours, pork/bacon,
   chicken, tomato, soft fruit, and cheese and yeast.

   Whilst not all food intolerances are related to meat and dairy products, it
   can be seen from the above list that vegetarians, and particularly vegans,
   will suffer less from food intolerance because they already eliminate some of
   the most common causes of intolerance.
   ___________________________________

  SYMPTOMS

   The most common symptoms of allergy include asthma, gastro-intestinal
   symptoms (nausea, vomiting, and diarhhoea), eczema, urticaria (hives),
   rhinorrhea (heavy discharge from the nose), and angio-oedema (swelling of the
   blood vessels). Other more long-term symptoms include can depression,
   anxiety, fatigue, migraine, sleeplessness and hyperactivity in children.
   ___________________________________

  TREATMENT

   As it is sometimes quite difficult to distinguish between a genuine food
   allergy and a food intolerance, treatment is often similar. The first step is
   to diagnose the food intolerance. This should not be done without medical
   supervision as some reactions to food intolerance can be dangerous.

   Sometimes the cause of a particular food intolerance is obvious, by the
   immediate effect that occurs on eating a particular food. In this case the
   treatment is simply to avoid that particular food. In most cases the
   suspected food is more difficult to track down. A diary kept of foods eaten
   and symptoms experienced can sometimes help detect the offending food or
   foods. Other factors such as the weather, menstrual cycles and difficult
   relationships can affect the symptoms. 

   Sometimes simple exclusion diets are advised where record keeping
   suggests a particular food may be the cause. So, for example, milk, egg
   or wheat may be avoided to see if symptoms improve.

   Other more restrictive diets may be advised, which only include a limited
   amount of foods which rarely cause a reaction. These diets are usually called
   exclusion diets. The idea of an exclusion diet is to identify an allergy or
   intolerance, by limiting the food to a very small choice, checking for
   symptoms and then very gradually introducing test foods to see if there is a
   reaction. An exclusion diet should not be followed without sound nutritional
   advice.

   You can seek the help and advice of The Vegetarian Society if you have any
   problems with your vegetarian or vegan diet, relating to diagnosis or
   treatment of a food allergy or intolerance.
   ___________________________________

  FURTHER INFORMATION

   Food Watch, 9 Corporation Street,
     Taunton, Somerset, TA1 4AJ. Tel: 0823 325022.
   Supplies specialised foods for allergy sufferers.

   Action Against Allergy,
     43 The Downs, London, SW20.

   Coeliac Society, PO Box 220,
     High Wycombe, Bucks, HP11 2HY.

   National Society for Research into Allergy,
     PO Box 45, Hinckley, Leicestershire.
   ___________________________________

  FURTHER READING

   The Food Allergy Plan,
     Dr Keith Mumby, Urwin Paperbacks.

   The Allergy Connection,
   Barbara Paterson, Thorsons.

   Food Intolerance Fact and Fiction,
     Dr Juliet Gray, Grafton Books.

   ___________________________________


//
This article is copyright to the Vegetarian Society (UK), but may be freely
copied for non-commercial use provided it is kept intact, not altered
and these lines are included.

For futher information contact: The Vegetarian Society, Parkdale, Dunham Road,
Altrincham, Cheshire WA14 4QG, England. Tel: (England) 061 928 0793
email: vegsoc@vegsoc.demon.co.uk
//



[The text of this file was obtained from the Vegetarian Society (UK) in
March 1995.]

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