Medical practice

NICE warns of alternative allergy tests

The Guardian reported that “alternative tests for children's food allergies – such as hair analysis or muscle weakness – must be avoided because there is little evidence they work.” The advice comes from new guidelines from the National Institute for Health and Clinical Excellence (NICE) and was reported widely in the media, which mainly concentrated on the warning against alternative allergy testing.

The purpose of these guidelines is to help GPs, nurses and other health professionals working in the community to identify and treat food allergies in children. They contain detailed guidance on the steps to follow when making a diagnosis and how to decide whether a child should be offered allergy testing.

As reported, the new guidelines also warn against the use of “alternative” test kits, available online and in some shops. NICE says there is little evidence that these work, some can leave children at risk of malnutrition from restricted diets, and that they are a waste of time and money. These tests include applied kinesiology, the Vega test and hair analysis.

Which tests should be avoided?

The tests not recommended by NICE are:

  • applied kinesiology (a process based on muscle testing)
  • Vega test (which involves measuring electromagnetic conductivity in the body)
  • hair analysis
  • serum specific IgG tests

These tests are reported to be available on the high street or the internet. Other alternative tests were assessed, such as the basophil activation test, but it was not clear whether these tests are available on the high street or internet.

NICE says that it could not identify any evidence that the tests worked. As such, the guideline development group agreed that these tests were not appropriate for diagnosing food allergies.

What else does NICE advise for children with allergies?

The advice covers children and young people up to the age of 19 who have symptoms or signs that could suggest a food allergy. It also focuses on children and young people who have conditions that put them at greater risk of developing a food allergy, such as asthma or eczema. They may also have a parent, brother or sister with a food allergy or allergy-related condition.

The advice sets out a detailed “care pathway” for health professionals to follow when dealing with a possible food allergy. A food allergy should be considered as a possibility if a child has one or more of the following signs and symptoms:

  • skin conditions, such as rash or eczema
  • digestive problems, such as nausea or constipation
  • respiratory complaints, such as shortness of breath or sneezing
  • anaphylaxis, a rare and severe hyper-reaction

Food allergies should also be considered in children who have not responded to treatment for atopic eczema or certain digestive symptoms such as chronic constipation, and who have not responded to treatment. 

A summary of the new advice

  • If a food allergy is suspected, doctors should take a detailed clinical history. This involves asking the patient and family specific questions about when symptoms started, how quickly they develop and when they occur. They should also physically examine the child for growth problems and other signs that they may not be getting enough nutrients from food.
  • Health professionals should use this information to decide whether allergy tests are appropriate and, if so, which test is suitable.
  • If an IgE-mediated food allergy is suspected, children should be offered a blood test or a skin-prick test. Children should not be offered a test called an atopy patch test or an “oral food challenge” without seeing a specialist.
  • If a non-IgE-mediated food allergy is suspected, health professionals should discuss with parents the avoidance of the possible food allergen for a trial period (known as an elimination diet).
  • Professionals should not use “alternative” diagnostic tests for food allergies.
  • Tests for food allergies should only be undertaken by health professionals with “appropriate competencies” and in certain cases only by specialists.

How do the new guidelines affect my child or me?

The guidelines also say that care for children with suspected food allergies should be “patient-centred” and that children, their parents and carers should be involved in discussions and make decisions about their care. For example:

  • When a food allergy is suspected, health professionals should give parents adequate information about food allergies. If possible, the child should also be able to understand this information.
  • Health professionals should always explain the tests for food allergy, covering the possible benefits and risks, and talk to parents and children about which test they would prefer.
  • Parents and children should also be offered advice about how to start an elimination diet if appropriate, including information about food labelling, how to ensure they still have a healthy diet, and with consideration of whether their culture or religion affects the foods a child can or cannot eat. Families should be offered support from a dietitian if needed.
  • Parents and children should also be given information about where to get support, including how to contact support groups.

What are food allergies?

Food allergies occur when the body’s immune system reacts negatively to a particular food or food substance. Allergens can cause a wide range of physical symptoms, including skin reactions (such as a rash or swelling of the lips, face and around the eyes), digestive problems such as vomiting and diarrhoea, and hay-fever-like symptoms, such as sneezing. These symptoms can appear suddenly, within minutes of eating the food, or can take hours or days to develop. Sometimes, symptoms can be severe and even life threatening (anaphylaxis). Such symptoms include swelling of the mouth and throat, breathlessness and racing heart rate. Food allergies are more common in children than adults, but children often outgrow their allergy. Children are most commonly allergic to cows’ milk, hens’ eggs, peanuts and other nuts, such as hazelnuts and cashew.

There are two types of food allergy, depending on whether the allergic reaction is triggered by an antibody called immunoglobulin E (IgE). These antibodies are the chemical signals that set off a sudden allergic reaction. Reactions that happen very soon after contact with the food, such as rash and swelling of the lips, are known as “IgE-mediated”. Reactions that take longer to appear, often hours or days after exposure, are known as “non-IgE-mediated”. Symptoms can include eczema or stomach problems and can continue for a longer time.

If the body’s reaction against a particular food is not caused by the immune system, the condition is known as a food intolerance (which is not covered by this guideline).

How common are food allergies?

NICE says that food allergies are among the most common allergic disorders and that the number of people with them has dramatically increased in the past 20 years. For example, food allergies are now thought to affect 6-8% of children up to the age of three across Europe and North America. Hospital admissions in the UK for food allergies have increased by 500% since 1990.

NICE also points out that of those children who report an allergy, up to 20% do not eat certain foods because they think they are allergic to them, without any confirmed diagnosis. The new guidelines are intended to provide consistency in the way that food allergies are diagnosed by NHS health professionals.

Where can I get more information?

NICE has produced information for parents and carers about the new guidelines.

NHS Attribution