Itching skin, difficulty breathing, a runny nose and nausea. These are just some of the symptoms that can be caused by food allergies. Yet in most people, these symptoms are due to something else. Allergies to substances other than foods are far more common than food allergies. Studies show that approximately one in three adults believe they have a food allergy. The reality is that true food allergy affects only 1 to 2 per cent of adults and 4 to 6 per cent of children. People tend to diagnose themselves believing they have allergic reactions to certain foods or food ingredients. Unfortunately self-diagnosis of food allergy often leads to unnecessary food restrictions and could lead to nutrient deficiencies especially in children.

What is a food allergy?

A food allergy is an adverse reaction to a food or food component that involves the body's immune system. The immune system produces large amounts of antibodies to fight against even small amounts of the food or food component that the body is allergic to (the allergen). This in turn produces histamine and other chemicals that cause symptoms such as a dripping nose, itchy eyes, dry throat, rashes and hives, nausea and diarrhea.

Is it really an allergy?

True food allergy is quite uncommon, affecting only 1-2% of adults and 4-6% of children. Common symptoms of a true food allergy include:

• Hives, itching, a rash or eczema
• Swelling of the lips, face, tongue or other parts of the body
• Wheezing, breathing difficulties or a stuffy nose
• Stomach pain, diarrhea, nausea or vomiting
• Dizziness, lightheadedness or fainting
• In severe reactions, shock, rapid pulse, a severe drop in blood pressure and loss of consciousness may occur

What foods can trigger food allergy?

The most common causes of food allergy, accounting for 90 per cent of all food allergies are:

• Cow's milk
• Egg whites
• Peanuts
• Wheat
• Soybeans

Other common causes are fish, shellfish, tree nuts, beans and corn.

What are the risk factors for developing food allergies?

There are several factors that increase the risk of developing a food allergy.

These include:

• Family history - if one of your parents has an allergy, you are twice as likely to develop one.
• Age - children are much more likely to have a food allergy than adults are and most food allergies develop in people less than 30 years of age. This is because the digestive system matures with age. Fortunately, most children outgrow their allergy by about age 6 although allergies to nuts and shellfish are more likely to be lifelong.

Food intolerance: ?

The Copycat A reaction to a food or food component is more likely to be a food intolerance rather than a true food allergy. Food intolerances do not normally involve the immune system but as they seem to trigger many of the same symptoms, they are often mislabeled as "food allergies'. The most common symptoms of food intolerance include hives, headaches, mouth ulcers, stomach pains and bowel irritation.

Common mistakes in food intolerance

Fresh and processed foods both contain a range of chemicals - some naturally occurring and others added to the food for quality or food safety reasons. It's easy to be led astray and blame the wrong food for an allergy or intolerance without realising that it's something else in the food that's causing the problem. The important thing to remember though is that most people consume a wide variety of food additives and ingredients daily with only a very small number being associated with adverse reactions.

Milk

Many people think that milk is bad for people with allergies especially asthma. In fact, this is not usually the case. While some people claim to feel better after cutting milk and milk products out of their diet, it is more likely to be that they suffer from intolerance to amines and they have cut out natural amines found in food such as tasty cheeses. True milk allergy is an allergic reaction to the protein components of milk. People with milk allergy need to avoid all milk and milk products. In children, the condition is often outgrown. Scientific studies show that milk and milk products do not usually cause stuffy noses and congestion.

Lactose Intolerance

A more common occurrence is lactose intolerance or an inability to digest lactose. Lactose is the natural sugar found in milk and milk products. An enzyme, lactase, breaks down the lactose in milk into smaller sugars so that it can be more readily digested. If lactose is not broken down, it is fermented by "friendly" bacteria in the small intestine. This can give rise to symptoms such as bloating, diarrhea and stomach-ache.

Lactose intolerance has been estimated to affect up to 80% of Asians, however in most cases, small amounts of milk and milk products can be tolerated by people with lactose intolerance especially when they are taken as part of a mixed meal. Dairy foods made with "friendly" bacterial cultures, such as yoghurts, have most of their lactose broken down by the bacteria and are generally well tolerated by people who are sensitive to lactose. Many cheeses, especially aged cheeses such as Swiss and cheddar cheeses, have much of the lactose removed and are a valuable source of calcium. Taking smaller amounts of milk at more frequent intervals and eating milk products as part of a meal are also ways to help include lactose-containing foods in the diets of people who have trouble digesting lactose, ensuring that they get enough calcium in their diet.

Asthma and food allergy: Is there any link?

Asthma can be triggered by a number of factors including dust, moulds, pollen, animals, air pollutants, weather changes, exercise, colds, certain medications and foods. Food-triggered asthma is uncommon occurring only among 6-8 per cent of children with asthma and less than 2 per cent of adults with asthma. After many years of scientific and clinical investigation, there are few confirmed food triggers of asthma. Sulphites and sulphiting agents in foods (present in fresh and dried fruits, wines, shrimp and bottled lemon or lime juice) and diagnosed food allergens (such as milk, eggs, peanuts, tree nuts, soy, fish and crustacea) have been found to trigger asthma in some people.

Breastfeeding and allergy

There are many good reasons to promote breastfeeding. However its effectiveness in helping to prevent food allergy is controversial. Some studies show that breastfeeding has a protective effect against food allergy while other studies show that breastfeeding may only delay the time until food allergy eventually appears. Food allergens eaten by breast-feeding mothers have been found in minute quantities in their breastmilk. It is believed that some infants experiencing allergic reactions on their first known ingestion of a particular food may have been actually sensitised by previous exposure to small amounts of the food allergens in their mother's breastmilk.

Points to remember:

Food intolerance can occur to naturally occurring food components such as salicylates and amines in some fruits and vegetables, as well as to a few food additives such as sulphites or yellow food colour, tatrazine.

People with food intolerance are usually sensitive to more than one food ingredient.

The degree of reaction and the time it takes for symptoms to occur after eating certain foods or food component s also vary between people.

If you suspect you have a food allergy or intolerance, the best way to identify the food component responsible is to seek expert medical advice from a doctor or qualified medical allergist. The offending food or food component can then be avoided. People who suffer from a severe reaction should wear an "alert" necklace or bracelet that notes this.