RAST tests that diagnose life threatening allergy should be available at all NHS Hospital Trusts. RAST tests are extremely reliable and any positive result should never be ignored.

There are a number of tests to diagnose food and chemical intolerance offered in the private sector. These tests are very expensive and none of them is very accurate. The only 100% accurate method of finding out exactly what one is intolerant to is by working through a dietary elimination and reintroduction programme.

Many therapists will offer a tailor made diet that says you must not eat certain foods - ever again. Or you should fast for 5 days then test out one food at each meal, or each day. Or they may put you onto a few foods diet for a few days then tell you to rotate your foods. None of these regimes will work very well for long. Certain foods like grain tend generally to give a delayed reaction, if you reintroduce foods too quickly, you could have reintroduced a number of different foods, so you would not know which you were reacting to. Fasts are not good for intolerant people. You can not fast for more than a few days, which may just be long enough for you to go into withdrawal from the foods that you are intolerant to. If you reintroduce foods when you are in withdrawal, you will not recognise a reaction.