Food intolerance used to be called 'food allergies'. However, there is a world of difference between a true food allergy, such as the infamous peanut allergy, which can kill almost instantly, and an intolerance to, for example, gluten leading to general poor health and obesity.

Food intolerance is not the same as food allergy. Many medical authorities, however, who really ought to know better, insist on classing them as the same, pointing out what is already known, that these types of problem do not show up in blood tests. The reason for this is that there is not usually any involvement with the immune system. There may be an inability to digest the food in question, perhaps because an enzyme is lacking, or some other difficulty.

Even though certain conditions are most often caused by an intolerance to one or two particular foods, the same symptoms may be brought on by different triggers in some patients. Different people are intolerant of different foods, and the same set of symptoms may be caused by a completely different food from one person to the next.

In case you're wondering why people eat foods they are sensitive to, I should point out that it's perfectly possible to have an intolerance to something as common as wheat for years without realising it. In a 3-year study at Addenbrooke's Hospital, Cambridge, UK, 60% of patients were found to be intolerant of wheat! In fact, you may be intolerant to wheat, dairy products or some other major part of your diet yourself.

The only reliable way to test for such a food sensitivity is by means of an exclusion diet (see "How to find out if you're food intolerant" further down).

Health problems which may be caused by food intolerance

Illnesses and problems that may be caused by food intolerance include:

- Arthritis
- Asthma
- Autism
- Chronic Fatigue Syndrome (ME)
- Coeliac disease
- Colic
- Crohn's disease
- Depression
- Eczema
- Gout
- Hyperactivity
- Irritable Bowel Syndrome (IBS)
- Migraine
- Obesity
- Rhinitis
- Urticaria

Other health effects may occur which are not listed. And, of course, intolerance to a food which is eaten regularly may also cause an existing condition to worsen.

How to find out if you are food intolerant

Food intolerance is not the same as food allergy (as mentioned already). Classic allergy tests don't work because they are testing for the wrong thing.

You may find the following types of test being offered to test for food intolerance:

- Skin test -
This is the classic test for immune response. Good for discovering if you have an allergy, but useless for pinpointing intolerance.

- Tongue test -
A modification of the skin test, again only suitable for discovering allergies, rather than food intolerance.

- RAST test (radioallergosorbent test) -
A blood test. Another test suitable for testing for allergies, but not for intolerance.

- Cytotoxic test -
Attractive in theory, but disappointing in practice. Do not take this test as the results are unreliable, with many false positives.

- Hair test -
A test for mineral deficiencies is offered as a way of diagnosing possible food intolerance. However, there does not seem to be any link between mineral deficiency and food intolerance.

- Blood mineral analysis -
Again, mineral levels are tested, but the link between mineral deficiencies and any food intolerance has not been demonstrated.

- Blood antibody test -
Any food antibodies found in the blood will demonstrate a food allergy. However, the lack of an antibody does not indicate that a food is tolerated.

Save your money. None of these tests are of any value in finding out if you are food intolerant or not. Only one reliable method exists: an exclusion diet. As mentioned already, in many cases, the condition which is suspected of being caused by food intolerance is so serious that this should only be undertaken under medical supervision.

Copyright 2005 Frann Leach