Herbal Health

April 20, 2009

OTHER FORMS OF FOOD ALLERGY: DIAGNOSING FALSE FOOD ALLERGY

Sorting out false food allergy from the real thing is far from easy. A skin-prick test will not distinguish someone with false food allergy from someone who has true IgE-mediated food allergy – both can produce a positive result. The radioallergosorbent test or RAST is usually positive as well, because the lectins or other offending food components bind IgE – in a true case of allergy, the IgE will bind the food antigen, but the results of the test look just the same. A simple modification of the RAST reveals the truth however: if extra food extract is added to the mixture, false food allergy will still give a positive test, but true food allergy will not.

Distinguishing between these two distinct types of food reaction is important to researchers, seeking to understand food allergy and establish its prevalence. As far as the patient is concerned, the distinction is less important, because the consequences and treatment are much the same. In most cases avoidance will be necessary. If drugs are used they will be ones that prevent mast cells from degranulating or counteract the effect of the mediators – in either case, it does not matter how the mast cells are being triggered.

It is possible, however, that those with false food allergy have some underlying deficiency that may make them more susceptible. It has been found that 50 per cent of patients with false food allergy are deficient in the element magnesium. A shortage of magnesium is known to affect histamine release and increase sensitivity to histamine. A nutritional assessment might be advisable for anyone known to have false food allergy.

Surprisingly enough, it is possible to ‘grow out of false food allergy. Children who have such a reaction to a particular food sometimes lose it, usually by the time they are eight years old. Exactly why this should happen is far from clear. There could be a change in the structure of the tissues that surround the mast cells in the gut, making them less accessible to food molecules.

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