Diagnosing food allergies in children is complex

By Eva Neumann Jan 16, 2012, 3:06 GMT

Berlin - When a baby takes a piece of bread in its mouth for the first time, this can be a critical moment in its life. If the child breaks out in an itchy rash, gets diarrhoea or starts to sniffle, this could be an early indication of a food allergy. The earlier an allergy is diagnosed, the sooner action can be taken to avoid the foods that set it off.

'There are no reliable studies on the number of children affected,' says Herbert Steinheuer, a child specialist working in the allergy field in Germany. 'Estimates indicate it is between 2 and 7 per cent of all children.' In most cases, the symptoms show within the first two years.

'Children affected by allergy react very soon after consuming the relevant food, showing symptoms of itchiness in the mouth, hives, shortness of breath or low blood pressure up to anaphylactic shock,' says Joerg Kleine-Tebbe, a German expert on allergies and clinical immunology.

The symptoms indicate that the body's immune system is reacting to the allergen, which it perceives as an attack. Food allergies in children are usually caused by proteins in basic foodstuffs like cow's milk, eggs, nuts, wheat, fish and soya. Peanuts have given rise to increasing allergic reaction over recent years.

Avoiding some of these foodstuffs can make considerable demands on the entire family and substitutes can be expensive. Before a specific foodstuff is avoided merely on grounds of suspicion, parents need to check whether it does in fact contain the allergen.

The basis for this is provided by a detailed diary on the food consumed. Then the services of a specialist paediatrician need to be called on. 'It is extremely important to be able to recognize the link between food intake and symptoms,' Steinheuer says. This then allows specific testing.

For adults, prick tests are often used. 'With children this procedure is problematic, because there are scarcely any areas of skin large enough,' Steinheuer says.

An alternative is testing for reaction to certain foods by measuring IgE antibodies in the blood. In complex cases, there is the possibility of going on a low-allergen diet and then testing specifically for possible allergens by systematically adding them to the diet under medical supervision.

Once the allergen has been identified, advice on diet is essential. 'The family has to be informed about which products contain the specific foodstuffs that have to be avoided. And about the substitutes needed to ensure an adequate diet,' says dietary expert Imke Reese.

In the case of pre-packaged foods, the list of ingredients needs to be studied carefully. The list should show if one of the more than 100 known allergens is present. 'The problem is that there is no final check on the product. It can happen from time to time that residues from earlier production runs get into the new food product,' says Reese.

'For this reason, many producers in the food sector provide the warning under the list of ingredients: May contain traces of xy.' Choosing what to eat when confronted with unpacked goods, when perusing the menu in a restaurant or on being invited to a children's birthday party present additional problems.

But there is good news. 'Around 80 per cent of the children affected get over these allergies again by the end of their school years,' Kleine-Tebbe says, adding that peanut allergies are the exception.