Allergy or intolerance?
FOOD INTOLERANCE NETWORK FACTSHEET
Food allergy or food intolerance?
Introduction
Family history
Who is affected?
How common?
Which foods?
Timing
Dose
Symptoms
Diagnosis
Treatment
Further information
Keywords: allergy, intolerance, allergen
Introduction
It is important to distinguish food allergy from food intolerance and understand the differences between them.
Food allergy is an immunological reaction to food proteins.
Food intolerance is a pharmacological reaction (like the side effects of a drug) to the chemicals in foods.
Family history
Allergy: hayfever, eczema or asthma
Intolerance: migraine, irritable bowel symptoms, behaviour problems
Who is affected?
Allergies are most likely to affect babies and young children because of their underdeveloped immune system.
Intolerances are likely to affect children are because dose for weight they consume a higher dose of food chemicals than adults. Women of child-bearing age are also vulnerable because of hormonal influence. Senior citizens are vulnerable because ageing livers and kidneys are slower to excrete chemicals from the body. Exposure to toxic chemicals, pharmaceutical drugs or illness such as gastrointestinal infection can trigger food intolerance.
How common?
Food allergies (not airborne allergies such as pollens) are considered to be relatively rare - affecting up to 8% of babies under 12 months, 3% of children under five, and less than 1% of adults.
Food intolerance is much more common, affecting babies (through breastmilk), children and adults. Effects are related to dose so in theory, everyone will react if the dose is high enough, and this was confirmed in a study with MSG. People most likely to be affected by nasty food chemicals are those who are most sensitive, and those who consume the highest doses. As additives continue to increase in our food supply every year, we should expect more people to be affected, especially children.
Which foods?
People with food allergies typically react to a few foods. Allergy is produced by a combination of inherited susceptibility with exposure so allergens vary. Common allergens overseas include buckwheat in Japan and lentils in Mediterranean countries. In Australia the most common foods are milk, soy, egg, peanut and fish. Allergies to the last two are more likely to last throughout life and allergies to peanuts are the most likely to be life-threatening.
With food intolerance, food chemicals most likely to cause problems are artificial colours, natural colour annatto (160b), preservatives, flavour enhancers (the 600 numbers) and some natural chemicals called salicylates and amines. These can be in many different and seemingly unrelated foods. For example, asthmatics are most likely to be affected by sulphite preservatives (220-228) in dried fruit, juice drinks, cordials, wine, sausages, some medications and a wide range of other foods.
Timing
Allergic reactions are quick. They usually occur within 30 minutes and are often easy to identify.
Food intolerance reactions can be delayed up to 48 hours or more, or effects can be cumulative. For instance, children rarely react to the preservative in one slice of bread, but if they eat bread every day - as children do - the effects can build up over a month and fluctuate with no obvious cause. In our experience, parents rarely realise their children are affected by food chemicals until their symptoms improve when nasty food chemicals are removed from the diet.
Dose
Allergic reactions can be to the tiniest amount of an allergen.
Intolerance reactions to food chemicals are dose-related. Some people are more sensitive than others. In theory, everyone will react to food additives if they consume enough and one study on MSG confirmed this, although a few of the subjects reacted to very high doses which were unlikely to be consumed in one sitting.
Symptoms
Allergic reactions can be itching, swelling, rash, spreading hives, vomiting, diarrhea, breathing difficulties and in the most severe of the allergic disorders, anaphylaxis can lead to collapse and death. By definition, anaphylaxis is an allergic reaction which involves two of the body's systems (eg respiratory and gastrointestinal or skin). Anaphylactic deaths as a result of insect bites or penicillin are usually very quick - within minutes - and due to cardiac arrest, anaphylactic deaths due to food allergies are usually due to suffocation (breathing difficulties).
Food intolerance reactions can be the same as above, as well as:
- skin (rashes, swelling)
- airways (asthma, stuffy or runny nose, frequent colds and infections)
- gastrointestinal tract (irritable bowel symptoms, colic, bloating, diarrhea, vomiting, frequent mouth ulcers, reflux, bedwetting, 'sneaky poos', 'sticky poos')
- central nervous system (migraines, headaches, anxiety, depression, lethargy, impairment of memory and concentration, panic attacks, irritability, restlessness, inattention, sleep disturbance, restless legs, moodswings, PMT).
Symptoms of food intolerance can come and go and change throughout life.
Diagnosis
Food allergies: involve an IgE response and can be identified by skin prick tests or RAST blood tests and confirmed with avoidance and challenge.
Food intolerance: there are no laboratory tests. The only way to identify provoking foods is through a comprehensive elimination diet and careful challenges.
Food allergies: avoidance with regular testing in the case of babies and children who may grow out of it. Life-threatening peanut allergies in particular are increasing. This is thought to be due to exposure through the use of peanuts in many Western-style processed foods. In allergic families, complete avoidance of peanuts, peanut-containing products (and also cow’s milk) is recommended for pregnant women for the last six weeks of pregnancy and throughout breastfeeding. Some schools have banned peanut butter and other peanut products. The recent case of a 13 year old boy at school camp who died after a dare to just taste peanut butter is an example. For more information see the Anaphlaxis Australia website.
Food intolerances: an elimination diet with challenges to pinpoint the culprits, gradual reintroduction of certain chemicals to ascertain tolerance, and subsequent avoidance to that limit. The elimination diet we recommend is 'failsafe', meaning Free of Additives and Low in Salicylates, Amines and Flavour Enhancers, supervised by a failsafe-friendly dietitian. The Food Intolerance Network can provide a list of dietitians on request to confoodnet@ozemail.com.au.
For an occasional antidote to a food intolerance reaction, try a pinch of soda bicarb in half a glass of water, or half to one Caltrate plain white 600 mg calcium supplement tablet.
The following review paper was used in writing this article: Clarke L, McQueen J, et al. (1996). "The dietary management of food allergy and food intolerance in children and adults." Australian Journal of Nutrition and Dietetics 53(3): 89-94. http://www.sswahs.nsw.gov.au/rpa/allergy/research/daareview.pdf
For food allergies, here is a useful USA site for restaurants and parents: http://www.idbylandau.com/v/vspfiles/resource/restaurant-food-allergy-guide.html
For food intolerance, Fed Up: Understanding how food affects your child and what to do about it (Random House, 2008) is a useful book, available through our website and in bookstores.
The information given is not intended as medical advice. Always consult with your doctor for underlying illness. Before beginning dietary investigation, consult a dietician with an interest in food intolerance. You can write for our list of supportive dietitians (confoodnet@ozemail.com.au)
© Sue Dengate last update November 2005.
