Remember the joke in which a patient consults a doctor because he is suffering with a headache?

The doctor tells him to stop banging his head against the wall and sends him away.

It is similar with food allergies: Don't eat the offending food and the annoying symptoms invariably disappear.

The problem is that symptoms may occur some time after a specific food has been eaten so you could end up eliminating all kinds of foods without finding the culprit.

Hippocrates, the father of medicine, was the first to document an unexpected reaction to food.

He noticed some individuals had a violent reaction to the tiniest amount of cheese, normally considered a wholesome food.

This type of immediate, hypersensitive reaction to a normally 'harmless' substance is called an IgE-based allergy.

Most reactions tend to be delayed (IgG based) and can take hours or days to manifest themselves, making detection much harder.

I spoke to Dr Mike Walker of Cambridge Nutritional Sciences (CNS) who specialises in IgG antibody testing.

He says food intolerances are widespread in our society and that susceptible individuals can be profoundly affected both physically and mentally.

Typical symptoms include chronic migraines, stomach cramps, bowel problems, hives, skin irritation and general aches and pains.

He explains that his lab uses the ELISA method for IgG antibody testing.

This is the only test that has given reliable and scientifically reproducible results in independent studies audited by the Department of Health.

More than 70 per cent of patients who changed their diet based on this test have found significant improvement in their symptoms.

Allergies aren't always the problem, though. If excessively sprayed with chemicals, any food can cause irritation or nausea.

Sometimes, reactions to food result from digestive problems, such as a lack of stomach acid or digestive enzymes. These juices are responsible for breaking down our food into small molecules for better absorption and, if they are lacking, indigestion and oating may occur.

Another common problem is the overgrowth of Candida albicans.

Candida is a type of yeast which is a normal inhabitant of the gut and is required to break down complex sugars.

As a result, it produces ethanol and carbon dioxide and can, if present in excess amounts, lead to bloating and significant digestive discomfort.

Disease-causing bacteria and parasites may also be responsible for unpleasant reactions.

If you have chronic health complaints that won't go away, it is worth consulting a qualified nutritionist who will play detective to find potential causes.

If food intolerances are suspected, a Food IgG test may be recommended.

Test kits are sent to patients who collect a small sample of blood from a finger prick and return it to the lab for analysis.

Patients then receive a report recommending elimination or reduction of certain foods.

Once offending foods have been avoided, patients usually see benefits within two to six weeks.

The cost of testing 40 common foods is £99, 93 common foods is £199.

For more details, contact Cambridge Nutritional Sciences on 01353 863279 or visit