It is not just artificial food additives that can cause food intolerances. By Kirsten Braun.
A food intolerance occurs when the body reacts abnormally to a substance found in a food. It differs from a food allergy in that it does not produce an immune system response (as in the case of a peanut allergy, for example).It is not uncommon for people with food intolerances to have multiple intolerances. While artificial chemicals such as preservatives, artificial colours and flavourings are often considered the main culprits, natural substances in fresh foods can also be a cause.
Five common natural food intolerances
Gluten is a protein found in wheat, oat, rye and barley. Simple gluten intolerance differs from coeliac disease which is actually an autoimmune condition characterised by a permanent intolerance to gluten. Coeliac disease damages the finger-like villi lining the small intestine which are responsible for the absorption of nutrients from food. Those with simple gluten intolerance may experience similar symptoms to those with coeliac disease but in their case gluten does not provoke an immune response and they do not have changes to their villi.
Lactose intolerance is the inability to digest lactose, the sugar found in milk and dairy products. It is caused by a lack of lactase, the enzyme required to break down lactose. While lactose is common in people from Asia, Middle East, Africa and in Australian Aboriginals, it is relatively uncommon in those with a European background.
Salicylates are a natural plant chemical and are high in many fruits (berries, melons, grapes, citrus, tomatoes), some vegetables (broccoli, silverbeet, avocado) nuts, herbs and spices, tea and coffee. Salicylates are more concentrated in or near the peel and in unripe fruits. Products in which salicylate rich foods are further concentrated can be particularly problematic (eg., juices, sauces, flavourings, dried fruit/fruit concentrates, jams, wine, beer).
Glutamates are a natural component of many fermented or aged foods. An artificial form is monosodium glutamate (MSG). While people are often wary of products with added MSG, many do not realise that glutamates also occur naturally in foods. Foods high in natural glutamates include sharp cheeses like parmesan and Roquefort, soy sauce, tomatoes and grapes. Many processed foods also have yeast extracts or hydrolysed proteins added to them as flavour enhancers, both of which are high in natural glutamates.
Amines are a by-product of the breakdown of protein or fermentation. They are found in cheese, yeast extracts, wine, beer, chocolate, nuts, fish, processed meats, pickled foods and soy products as well as in some fruit and vegetables. Many foods high in amines are also high in glutamates.
Symptoms of food intolerance
The symptoms of food intolerances are varied but typically involve:
- gastrointestinal (diarrhoea, bloating, flatulence, stomach pains, constipation, nausea, mouth ulcers)
- skin (hives, eczema, rashes)
- respiratory (sinusitis, asthma)
- central nervous system (irritability, headaches, restlessness and sleep disturbances).
Food intolerances tend to be dose dependent meaning that the severity of symptoms is related to the amount consumed. People may be able to consume a certain amount without displaying any real symptoms. This is referred to as a tolerance limit. People with a low tolerance limit, however, can suffer from the cumulative effects of even small amounts.
Finding out if you have a food intolerance
Those who believe they are lactose intolerant can undergo a hydrogen breath test. For other food intolerances, however, there are no simple tests to determine if a person is affected. Unlike testing for a food allergy, a skin prick or blood test cannot detect a food intolerance (as it does not produce an immune response).
The only accurate way is to follow a strict elimination diet, avoiding a list of certain foods for a period of time until symptoms settle. Different foods are then reintroduced to see if they cause a reaction. This is referred to as a 'challenge'. It is recommended that elimination diets be conducted under supervision from a doctor and/or dietician. Those who believe they are gluten intolerant should firstly be tested for coeliac disease.
Problems with self-diagnosis
Unfortunately, many people do not follow a proper elimination diet, instead choosing to self-diagnose a food intolerance. Self-diagnosis can present a number of issues. If the self-diagnosis is not accurate a person may eliminate foods unnecessarily. For example, the person who entirely eliminates gluten because pizza made them sick might actually have an intolerance to the amines found in the pizza topping.
Self-diagnosis can also result in people not receiving proper advice about what foods and food products to avoid. Many people with lactose intolerance can actually consume small to moderate amounts of dairy without symptoms, making it unnecessary to completely eliminate dairy from their diet.
People might also eliminate entire food types without finding alternate sources of important nutrients (eg., not replacing dairy with other calcium rich foods or not replacing gluten rich carbohydrates with other carbohydrates). There is also the risk that someone who self-diagnoses may in fact have a more serious medical condition which is responsible for their symptoms.
For more information on food intolerances, including a sample elimination diet see the Royal Prince Alfred Hospital Allergy Unit website
Last updated: March 2012
© Women's Health Queensland Wide Inc. This article was written by Kirsten Braun and reviewed by the Women's Health Queensland Wide editorial committee. It was published in HealthJourney 2012_1.pdf.