What is the difference between food allergy and food intolerance?A food allergy is an abnormal immune system response to the introduction of a food an ordinarily harmless substance into the body. A reaction can occur within minutes, or a few hours, after the food is ingested. A food intolerance is an adverse reaction to a food that does not involve the immune system. Reactions can be immediate or delayed up to 20 hours after a food is eaten.
What are the symptoms to watch out for?Symptoms of intolerance are sometimes vague and can include a combination of the following: gastrointestinal problems such as bloating and wind, diarrhoea, nausea and indigestion, aggravation of eczema or asthma. Food intolerances can sometimes mimic symptoms of other medical conditions - it is important to get checked out by a doctor to eliminate other problems first.
Diagnosing a food intoleranceThe elimination diet and oral challenge test is the only way to diagnose a food intolerance. All suspected foods are completely removed from the diet for one to three weeks. A small amount is then reintroduced and if symptoms reappear, the intolerance is confirmed. This test can also be performed to diagnose a food allergy. It is important that this test is undertaken under the supervision of an experience doctor, allergy specialist or Registered Dietitian to make sure that proper nutrition is maintained. If there is a risk of a severe reaction, foods should never be reintroduced without first consulting a health professional, especially in children.
Undertaking an elimination diet to get to the bottom of what's causing a food intolerance can be a slow frustrating process. Try to stick with it - being free of symptoms will be well worth it in the end. Unfortunately, there are no 'quick fixes' where diagnosing an intolerance is concerned; be suspicious of anyone offering an easy answer.
Common culprits in food intoleranceAlmost any food can cause an intolerance, but there are some types of intolerances that occur more than others.
Lactose intolerance, a condition in which a person cannot digest the sugar found in dairy products, is one of the most common food intolerances.
A sensitivity to naturally occurring food chemicals can cause symptoms of intolerance. These chemicals include:
• salicylates, natural preservatives found in a wide variety of fruits, vegetables, nuts and spices
• amines, produced during fermentation, aging and ripening
• glutamate, an amino acid found naturally in all protein foods.
A specific type of intolerance can develop to the protein in wheat and other grains called gluten. This condition is called Coeliac disease, and it is estimated that 1 in 300 New Zealanders are affected.
What should I do if I have been diagnosed with food intolerance?Most intolerances are dose-dependent, meaning that you have to consume a certain amount of the offending substance before symptoms appear. You may be able to consume small quantities of the food, unlike people with allergies who must remove even the tiniest traces. The amount tolerated is very individual, so once you have discovered what is causing your symptoms, you'll have to learn how much affects you.
Coeliac disease is an important exception to this rule - gluten must be strictly avoided.