FoodWorks – Food Intolerances - FoodWorks for Life - Health & Issues

• Food Allergies
• Food Intolerances
• Heart Disease

Food Intolerances

Around 1 in 20 infants and 1 in 100 adults are allergic to certain types of food. Severe reactions result in difficulty breathing, severe rashes, swelling of the face or throat, dizziness, stomach upsets or a drop in blood pressure (shock) and loss of consciousness. Other people complain of symptoms after eating like headaches, bloating or mouth ulcers that are not caused by allergies. Some of these result from enzyme deficiencies or food intolerance.

• What is food intolerance?
• Natural substances in foods can cause food intolerance
• Other adverse reactions to food
• Are allergy tests necessary?
• Non-conventional tests can be misleading
• Management of food intolerance may involve elimination diets

What is food intolerance?

Food intolerance can be a difficult concept to understand. Sometimes substances within foods can increase the frequency and severity of migraine headaches, skin rashes (like hives) or the stomach upset of an irritable bowel. It's not so much that these substances are the cause of symptoms, but rather that they aggravate an underlying condition. It's a bit like having a sore on your leg and you go swimming in salt water. The salt water makes it hurt more, but didn't actually cause the sore in the first place.

The best approach is to first consult your doctor to:

• Make a diagnosis e.g. migraines, hives, irritable bowel, recurrent mouth ulcers
• Determine whether dietary (or other) factors play an aggravating role and
• Identify individual triggers to be avoided.

Natural substances in foods can cause food intolerance

Natural chemicals are found in all of the foods that we eat. Food is composed of protein, carbohydrate, fat and various nutrients as well as a number of natural "chemicals". These naturally occurring molecules often add flavour and smell to food. Sometimes they will trigger symptoms in unlucky individuals.

• monosodium glutamate (MSG, 620, 621, "flavour enhancer") - was originally isolated from seaweed in 1908 by a Japanese chemist. It also occurs naturally in such foods as camembert and parmesan cheeses, tomatoes, soy sauce and mushrooms. MSG stimulates nerve endings, perhaps accounting for its function as a "flavour enhancer" amongst other properties.
• Vasoactive amines such as tyramine, serotonin and histamine are well known triggers of migraines in some patients and are present naturally in pineapples, bananas, baked meat, vegetables, red wine, wood-matured white wine, avocados, chocolate, citrus fruits and mature cheese. Amines can act directly on small blood vessels to expand their capacity, which may explain their effect on flushing, migraines and nasal congestion in some patients.
• Salicylates are aspirin-like compounds present in a wide variety of herbs and spices, as well as fruit and vegetables. Indeed, reactions to these may be even more common than reactions to artificial colours and preservatives. Aspirin can trigger hives (urticaria) by acting directly on skin mast cells. Natural and structurally similar salicylates can also worsen hives in some patients.
• Toxins - Other than contamination of food with micro-organisms or their products (spoilage, food poisoning), some foods contain toxins than can cause severe symptoms in the body. For example, if some types of fish are stored poorly, their gut bacteria can convert histidine to histamine, resulting in allergy-like symptoms.
• Irritants - caffeine and curry are gut irritants and can trigger indigestion in some people.

It is important to realise that reactions to these substances are not due to allergy, and so allergy testing is of little use in helping us to decide what to avoid.

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Other adverse reactions to food

There are many other adverse reactions to foods, apart from allergy and intolerance, including:

• Enzyme deficiencies - Some people are born without enough enzymes to digest, absorb or deal with some foods. For example, a deficiency of the enzyme lactase results in lactose intolerance. The inability to digest lactose can result in bloating, wind, nausea and diarrhoea after having dairy products. Similarly, people with low levels of alcohol dehydrogenase will experience flushing and severe nausea because they are unable to metabolise toxic breakdown products of alcohol.
• Coeliac disease - Coeliac disease is not an allergy, but an immune system response to food containing gluten. When gluten-containing cereals (eg. wheat) are eaten, inflammation of the gut occurs, resulting in poor absorption of nutrients. Major symptoms are gut upset, fatigue, anaemia or weight loss.
• Food aversion - This is a condition where a person not only dislikes a food, but also experiences unpleasant physical symptoms when they see or smell it. Symptoms are triggered by emotions associated with food rather than the food itself. This does not usually occur if the food is disguised.
• Underlying anxiety - Anxiety can result in unconscious over-breathing or hyperventilation. The symptoms than result (dizziness, tight chest, blurred vision or numbness) can be very distressing, and thus the symptoms can sometimes resemble food allergy.

Are allergy tests necessary?

A diagnosis of adverse reactions to food is based on the history, response to treatment and testing where necessary. Allergy tests (Skin Prick tests or CAP/RAST) are of little use unless the history suggests that an allergy (as opposed to an intolerance) is the problem.

Non-conventional tests can be misleading

Some adults and children in Australia and New Zealand use non-conventional methods for diagnosing health problems, including allergies. Unfortunately, a number of misleading tests have been promoted for diagnosing allergies, in the absence of any credible evidence of their reliability. Various methods such cytotoxic food testing (Bryans' test), Alcat testing, kinesiology, allergy elimination techniques, Vega testing (http://www.mja.com.au/public/guides/vega/vega.html), pulse testing, reflexology and hair analysis have all been proposed as being useful for diagnosing allergic conditions. Not only do these tests lack any scientific rationale, but they have been shown to be inaccurate and poorly reproducible when subjected to careful study. Treatment based on inaccurate results is not only misleading, but can result in ineffective and sometimes harmful treatments, and can delay more effective therapy.

Management of food intolerance may involve elimination diets

Once a diagnosis is made (from symptoms such as migraines, hives, eczema, irritable bowel or recurrent mouth ulcers), the history may help identify the role of dietary or other factors in making symptoms worse. The only reliable way to ascertain whether diet is playing a role is by being placed on a temporary "elimination diet" under the supervision of a skilled dietitian and medical practitioner. If the diet helps, this is followed by challenges under controlled conditions to identify dietary triggers so that they can be avoided in the future.

It is important to emphasise that "elimination diets" must only be undertaken for a short term, under strict medical supervision and only for very good reasons. Prolonged restricted diets can lead to problems with nutrition, particularly in children.

Disclaimer

The content of this information has been reviewed by ASCIA members, represents the available published literature at the time of review and is not intended to replace professional medical advice. Any questions regarding a medical diagnosis or treatment should be directed to your medical practitioner.

For further information on allergy, asthma or immune diseases visit www.allergy.org.au - the website of ASCIA is the peak professional body of Clinical Allergists and Immunologists in Australia and New Zealand.

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