18 March 2010
Food allergy generally begins in childhood and can trigger a wide range of symptoms from vomiting, persistent diarrhoea and abdominal pain to eczema, skin rashes and wheezing. With so many symptoms that could have other causes it is often hard to be sure that food is to blame or to find out which food. Reactions may occur immediately after eating a specific food or may be delayed for hours or even days. If you are worried that your child might be allergic to a certain food, you should seek expert medical advice.
An allergic reaction generally occurs when the immune system wrongly perceives a harmless substance as a threat and an immune response is triggered, producing a large amount of antibodies in the blood. This can cause or contribute to various conditions such as eczema, urticaria, hay fever, asthma, diarrhoea and even failure to thrive. With the later introduction of solid foods between four and six months, the incidence of food allergy in young babies has become less common. However, it is still babies under the age of eighteen months who are most likely to develop an allergy.
The commonest foods that carry a risk of allergic reaction in babies:
- Cow's milk and dairy products.
- Wheat-based products.
- Fish and shellfish.
- Citrus and berry fruits.
A family history of allergies
There is a lot of anxiety about food allergies. However, unless there is a family history of allergy, food allergies are quite rare. The risk of a child developing an allergic disorder more than doubles if there is a family history of parent or sibling with an atopic disease such as asthma, eczema or hay fever. In this case, breastfeeding for at least four, and preferably six, months seems to offer some protection. Bear in mind if you are breastfeeding that by eating certain foods like dairy products, eggs, oranges or wheat, the allergic substances may be transmitted through your breast milk. This can then cause a reaction in your baby (like eczema), particularly if there is a family history of atopic disease. Don't cut major food groups such as dairy products in your own diet as you may become deficient yourself. Always check with a dietitian first.
Do not introduce any foods that might cause an allergy before six months at the earliest. Instead, only start weaning with low-allergen foods like baby rice, root vegetables, apple and pear. If there is a family history of allergy to a particular food, avoid that food until your child is at least one year old. Do not remove key foods from your child's diet without first consulting a doctor. If you suspect that your child is allergic to a common food such as milk or wheat, seek expert advice on planning a balanced diet.
Many children outgrow food allergies by three to five years. However, there is no cure for some life-long allergies and the only way to remain healthy is to avoid the problem food. A young baby's immune system is not fully matured and babies can become ill very quickly, so never hesitate to call a doctor if you are worried.
How to diagnose a food allergy
The only accurate way to diagnose food allergies is to eliminate the suspected or most common allergens, wait for symptoms to cease and after a period of about six weeks, reintroduce them one by one until the symptoms reappear. This is called an elimination diet followed by food challenging. This type of diet should only be done under medical supervision and with the help of a state-registered dietitian. Other methods such as electrode testing and skin prick tests are not accurate means of diagnosing food allergies.
Specific food allergies
Cow's milk protein allergy: This is the most commonly occurring allergy in children. An allergic reaction to infant formula or any dairy product can occur in a matter of minutes, or even after a few days to weeks. Symptoms can include cramps, diarrhoea, vomiting, a skin rash or breaming difficulties.
If your baby is sensitive to cow's milk-based infant formula, consult your doctor, who might recommend either a soya-based formula or a specially designed hypoallergenic formula. About 30 per cent of babies who are allergic to cow's milk also become allergic to soya milk. Breast milk is the best milk for babies but breastfeeding mothers will need to eliminate dairy foods from their own diets as these can be transferred to their baby through breast milk - only do this under the guidance of a dietitian.
Food additives and colourings: Some widely used food additives like the food colourings tartrazine have been associated with allergic reactions in a small minority of children. There have also been reported links between hyperactivity and diet. There is some evidence that in a small minority (a much lower incidence than is perceived by parents), additives such as flavourings and colouring or foods such as milk or wheat may change behaviour.
Food intolerance: A food intolerance, sometimes called a false food allergy, is a condition where the body is temporarily incapable of digesting certain foods. It is generally short-lived and is not the same as a true food allergy, which involves the immune system. However, it can provoke the same symptoms, so if you suspect that your child is allergic to a common food like cow's milk, you should consult your paediatrician before changing milk formula. It is quite possible that your baby's reaction is only temporary. If your child is found to be allergic to a basic food like wheat, you should always seek expert advice as to how you can keep meals balanced.
Gluten intolerance: Gluten is found in wheat, rye, barley and oats and is therefore present in foods like bread, pasta and biscuits. Some people suffer from a permanent sensitivity to gluten - a condition known as coeliac disease - which although rare, is a serious medical condition. It is diagnosed medically by a blood test and confirmed by actually looking at the gut wall using endoscopy. Symptoms of gluten disease include loss of appetite, poor growth, swollen abdomen, pale, bulky, frothy and smelly stools. Foods containing gluten should not be introduced into any baby's diet before six months. Cereals used between four to six months should be gluten free, such as rice or maize. When buying baby cereals and rusks, choose varieties that are gluten free. Baby rice is the safest to try at first, and thereafter there are plenty of alternative gluten-free products such as soya, corn, rice, millet, rice noodles, buckwheat spaghetti and potato flours for thickening and baking.
Peanuts: Peanuts and peanut products can induce a severe allergic reaction called anaphylactic shock, which can be life threatening. In families with a history of any kind of food allergy, it is advisable to avoid ail products containing peanuts until the child is three years old and then seek medical advice before introducing peanut products into the diet Vegetable oils, which may contain peanut oil, will not cause a reaction as the oil is refined, removing any traces of peanut protein. Provided there is no family history of allergy, peanut butter and finely ground nuts can be introduced from six months. Whole nuts should not be given to children under the age of five because of the risk of choking.