Imagine living with the reality that even the most healthy food could be a problem for you, could make you feel unwell, could give you an uncomfortable rash or in severe cases, could be life threatening. It seems that many people these days claim to have a ‘food allergy’, however a true food allergy is not as common as you may think.
In fact, the adverse reactions to food that are commonly thought to be an allergic reaction are quite often due to a food intolerance rather than an allergy. In this feature article, we will look at the difference between food allergy and food intolerance, the symptoms, common trigger foods, treatment options and where to go for more information.
A food allergy is when a person’s immune system produces antibodies to a particular food protein that it believes is harmful. When an individual eats that food, their immune system releases chemicals, including histamine, in order to protect the body.
Some of the most common allergic reactions include eczema, asthma and hay fever and in severe cases, anaphylactic shock.
Foods that are commonly responsible for allergic reactions in people include:
tree nuts (e.g. walnuts and cashews)
Although research is being conducted into food allergies and new treatments, at present, total avoidance of the problem food is the only way to prevent a reaction.
A food allergy is usually first identified as a problem for infants, toddlers and young children. While children are often allergic to 2-3 (sometimes even more) different foods, fortunately most tend to grow out of some allergies, particularly egg and milk allergies, by school age.
However, allergies to nuts and seafood can often persist into adulthood. Occasionally new food allergies can arise in adulthood however this usually occurs with crustaceans and other more exotic foods that are not eaten during childhood. However, most adverse reactions to food, which develop in adulthood, are due to food chemical intolerances, rather than allergies.
Diagnosing a food allergy
Unfortunately, most of these methods are not supported by scientific evidence and as such are considered unreliable. Some of these diagnostic tests and treatments include Kinesiology, ALCAT blood testing, Iridology, Hair analysis, Acupuncture and Reflexology.
For a firm diagnosis of a true food allergy, an immunologist needs to conduct a skin prick test or a blood test (RAST or radioallergosorbent test) to detect if someone has antibodies to the common food allergens.
What is anaphylactic shock?
An anaphylactic reaction is a severe, rapidly progressive allergic reaction that can be life threatening unless treated immediately. Symptoms can begin within minutes of exposure with hives and swelling of the mouth and throat area, vomiting, diarrhoea, asthma, difficulty breathing and even loss of consciousness.
People with severe food allergies need to be very careful as even a trace amount of the problem food can cause a reaction in some individuals. People who are experiencing an anaphylactic reaction need an immediate injection of adrenalin to help reverse the symptoms and prevent the progression of the reaction.
Unlike food allergy, a food intolerance causes an adverse reaction to a food but it does not involve the person’s immune system. Rather, the symptoms of food intolerance are triggered by food chemicals.
Many people may not be aware of intolerances to food chemicals. These may be artificial chemicals (food additives) added to processed foods but they also include chemicals found naturally in foods. The common natural food chemicals that may cause problems in sensitive people include:
Salicylates found in many fruits and vegetables, tea, coffee, fruit juices, beer, wine, soft drinks and cordials, honey, jam, peppermint, commercial sauces and stocks.
Amines found in some vegetables and fruit (particularly bananas and avocados), cured meats, cheese, chocolate, beer, wine, caffeine, fish products, commercial sauces, stocks and yeast extracts.
Glutamates present in mushrooms, tomatoes, sultanas, cheese, commercial stocks, soups and sauces, processed meats, yeast extracts.
The symptoms of food intolerance are varied and can often be very similar to those of a milder food allergy which is why some people may report they have a food allergy when really, it is far more likely to be a food intolerance, or even another medical condition altogether. People with a food intolerance may suffer from symptoms such as hives, skin swellings, eczema, bowel irritation and stomach pains, headaches, fatigue, irritability, muscular aches and pains, poor concentration. In children, behavioural problems associated with disorders such as ADHD (attention deficit hyperactivity disorder), can also be aggravated if the child is sensitive to some food chemicals.
People may be born reacting to certain chemicals, or the intolerances can develop in later life, usually triggered by environmental factors such as illness or a change in diet.
Identifying food intolerance
Intolerances to food chemicals can only be identified by an elimination diet and challenge procedure, usually best conducted under the supervision of an Accredited Practising Dietitian (APD) as initially the diet is quite restrictive (and bland in flavour as foods high in food chemicals tend to be the most tasty!) The elimination diet involves following a low chemical diet for 3 or 4 weeks and then ‘challenging’ with carefully selected foods, one at a time, to identify the chemicals that cause the symptoms.
Once identified, problem food chemicals, such as food additives and artificial colours and flavours, can be avoided by checking food labels and staying away from foods that contain these chemicals. However, people who are sensitive to natural food chemicals may find enjoying even the most healthy whole foods a daily challenge.
Food intolerance reactions are dose dependant. This means that some people may be able to tolerate small amounts of a chemical before they experience an adverse reaction. People who are very sensitive have a far lower threshold than others and may need to eat mainly low chemical foods, while others will be able to enjoy a more varied diet just by being careful to not overindulge in the chemical rich foods. There are also people who may be able to build up their tolerance threshold over time by gradually increasing the amount of low-moderate chemical foods they consume. For these fortunate people, a relatively normal diet is achievable.
People with lactose intolerance have difficulty digesting lactose, which is the type of sugar found naturally in milk and many dairy foods. Many people with this condition can however tolerate small amounts of these foods, especially yoghurt and matured cheese that are often quite low in lactose. Again, the key to managing lactose intolerance is determining a tolerance threshold to avoid the uncomfortable symptoms of bloating, wind, cramps and diarrhoea, or finding equivalent lactose free alternatives, such as enriched soymilks
People who have coeliac disease are sensitive to gluten which is a protein found in common grains including wheat, barley and rye. Oats may also be a minor source of gluten. The reaction causes inflammation and damage to the lining of the small bowel, which impairs its ability to absorb nutrients.
Those affected may experience symptoms of fatigue, diarrhoea, cramping and bloating, nausea and vomiting, weight loss and constipation. These can also be symptoms of many other medical conditions including other food sensitivities. So, it is important not to self diagnose coeliac disease or ‘gluten intolerance’ and unnecessarily start excluding bread, pasta, breakfast cereals and other gluten containing foods from your diet. A firm diagnosis relies on a small bowel biopsy, which requires the person to have been including gluten in their diet up until the testing. Check with your doctor before making your diet too restrictive!
Currently, the only known treatment for coeliac disease is total avoidance of gluten. This is important as if untreated, the condition may lead to nutritional deficiencies, osteoporosis and even gastrointestinal cancer.
For those who need to exclude gluten from their diet there are a number of nourishing substitutes including rice, potato, buckwheat, millet, corn, polenta, soybeans and other legumes. Many of these ingredients can be purchased as flours suitable for baking. There are also an increasing number of gluten free commercial products including breads, biscuits, pasta and flours available in supermarkets.
What you can do if you think you have a food allergy
Removing a food or an entire food group from your diet may leave you with an unbalanced diet, possibly causing you to miss out on essential nutrients you need each day to stay healthy. There may also be other medical reasons for the symptoms you are experiencing, rather than your diet.
Before jumping to conclusions, consult your doctor to rule out that a medical condition is not the culprit. If food appears to be implicated, you should be referred to an Accredited Practising Dietitian (APD) or a Registered Dietitian who will provide professional guidance to identify the problem food or foods without restricting your diet unnecessarily. If a true food allergy is suspected you will need to get a referral to a specialist allergy doctor for further testing.