What is the difference between IgE and non-IgE mediated allergies?
Immunoglobulin E (IgE) is an antibody present in the blood, usually in small concentrations. When triggered by an allergen (usually proteins in certain food) the body releases antibodies to fight what it thinks are offending cells. This leads to an increase in histamine levels in the body and the classic allergic reactions (such as inflammation of the face and limbs and anaphylaxis). This reaction can be measured by blood tests as there will be an increase of IgE levels in the blood; these are known as IgE allergies.
In non-IgE allergies the person suffers with some of the same symptoms, but does not make IgE antibodies against the allergens. There can be a delayed reaction of up to 72 hours after ingestion of the offending food, which means that it is often hard to pinpoint which food is causing the reaction (especially as so much of what we eat nowadays is processed and contains so many ingredients).
What is the difference between food intolerances and non-IgE mediated allergies?
Food intolerance is a general term used to describe a large group of reactions including toxic, metabolic, pharmacologic or other undefined allergic reactions. Non-IgE mediated allergies refer to immunological reactions only, they generally occur over a longer period after ingestion and most often (though not always) affect the gastro-intestinal system.
Effects on the body
- Depression and irritability
- Fatigue (from poor absorption of nutrients)
- Hyperactivity (in some cases)
- Food Refusal or Food Avoidance (as the child is aware that they will be in pain after eating)
- Perianal Redness (especially in babies, where allergens excreted by the body stay in contact with the skin and cause a reaction)
- Atopic Eczema (or atopic dermatitis, this is an inflammation of the skin which causes itching, reddening, dryness, blistering and scaling, it is not contagious, has varying degrees of severity and can flare up in relation to increased intake of allergenic foods)
- Pale skin
- Angioedema (swelling of the body)
- Erythema (redness of the skin due to inflammation of skin cells which in the allergic child often presents itself as a flushed face)
- Urticaria (nettle rash or hives made up of red or yellow wheals that look like blisters which are itchy and hot)
- Oedema (water retention)
- Pruritis (General Itching)
- Diarrhoea and/or blood stained or mucous in stools (and dehydration as a result) is a common symptom of non IgE mediated allergies and can go onto cause anaemia (due to poor absorption of nutrients) if left unchecked.
- Constipation (again due to poor absorption of nutrients)
- Crohn’s disease (commonly affects the small intestine, causing inflammation, deep ulcers and scarring to the wall of the intestine)
- Abdominal cramps
- Severe nausea
- Vomiting after feeding (in a babies with allergies this is hard to measure, as many ‘normal’ babies vomit after feeding and are often diagnosed as having reflux and given antacid medications)
- Abdominal distension
- IBS or Irritable Bowel Syndrome (common condition of the digestive system. It can cause bouts of stomach cramps, bloating, diarrhoea and constipation and is thought to be caused by a sensitive gastro intestinal system)
- Stomach ulcers
- Leaky Gut Syndrome (found alongside IBS, eczema and arthritis, the damaged or dysfunctional surface of the gut allows larger antigenic molecules, bacteria and other toxins to pass into the stomach; water retention is a symptom of leaky gut syndrome)
- Wind and indigestion
- Joint/muscle pain
- Low blood sugar
- Faltering growth or ‘Failure to Thrive’ (due to poor nutrient uptake by the gastrointestinal system)
- Mouth ulcers
- Itching of palate and tongue
- Glue ear (middle ear fills with glue like substance instead of air, thought to be an occasional side effect of coughs and colds when extra mucous is produced, allergic children are thought to suffer more from these symptoms, so may be more prone to this condition)
- Withdrawal symptoms (removal of a food containing allergens from the diet may mean mild but chronic symptoms appear as antigen concentrations falls and as a result you get withdrawal symptoms, as the antigens are cleared the body is in antibody excess and the symptoms finally clear)
- Asthma, coughing and wheezing
Skin Prick Tests/Blood Tests
IgE levels can be tested for through blood tests; but for non IgE-mediated allergies blood tests will come back negative.
This is difficult to attempt especially with a child, as it requires thorough compliance. A faster heartbeat after food is ingested may indicate a food culprit and can be an excellent primary indicator (but obviously not to be tried in the case of anaphylaxis).
Vega Tests and Electroacupuncture (EAV)
Vega machines are a type of electroacupuncture device dating from the 1970s (descendent of the 1950s EAV machines) which practitioners claim can diagnose allergies and other illnesses by measuring electrical pulses in the human body. There have been few clinical studies on Vega Tests and they vary by practitioner. NICE (National Institute for Health and Clinical Excellence) has advised against their use as there is no clinical proof that these machines are effective.
Kinesiology (Muscle Testing)
Developed in the 1960s it relies on energy fields within the body to diagnose allergies and is popular with chiropractors. Although considered to be an inexpensive and immediate form of diagnosis there are few studies done on it and there is poor scientific evidence of its effectiveness.
IgG ELISA Allergy Test
The test measures IgG and IgG4 antibodies to various foods. Most people develop these antibodies to food they eat and this is a normal non-specific response indicating exposure but not sensitisation; for example high IgG4 levels after cat allergen exposure showed cat allergy protection, not sensitisation.
Elimination Diets and Reintroduction Challenges
This is considered to be the ‘gold standard’ in the UK. There is no cost involved and it is sensitive to all adverse reactions. Although it can be time consuming and there is no way of confirming results, it is widely accepted by doctors as confirmation of a non-IgE mediated allergy.
To help your GP with diagnosis it is commonly advised to keep a food diary and note reactions to certain food. After discussion with your GP and referral to a dietician so that an alternative balanced diet can be agreed, a two to six week exclusion diet can be undertaken (depending on severity of symptoms) after this time you should see the dietician and/or GP and consultant to discuss the next steps for prevention and treatment.
Prevention and treatment
The causes of allergies are not yet know, so there is no known way of preventing them.
Prevention of symptoms is the same as with normal food allergies, avoidance of food which causes adverse symptoms in the child, taking careful note of ingredients on processed food packages and understanding which ingredients can cause symptoms. For example for a diet free from Cows Milk Protein (CMP), parents are to avoid not only milk and skimmed milk powder, but also less obvious ingredients like whey, casein, lactoglobulin and lactalbumin.
Elimination diets followed by hospital supervised oral food challenges are important in the identification and treatment of an allergy. As childhood food allergies to common allergenic foods such as milk, egg, wheat and soya are usually outgrown; oral food challenges are an important part of the long-term management.
Treatments for the child are to reduce symptoms rather than the allergies themselves as there is currently no treatment available.
Antihistamines can be given (available on prescription from your GP only, be especially careful of use in babies and young children). Antihistamines will reduce the histamines in the body and help with gastrointestinal, urticaria, angioedema and nose complaints.
Bronchodilators (blue asthma inhalers, again on prescription) can be given to reduce wheezing, coughing and ease any asthma symptoms.
Corticosteroids can be applied to the skin to reduce inflammation and itching, especially in the case of eczema.
What does this mean for parents of a child with non IgE mediated allergies?
If the blood test for your child has come back negative this does not mean that they do not have a non-IgE mediated allergy instead. Talk to your GP about elimination diets and referral to a dietician.
Try to avoid expensive and unproven tests offered by companies who may only be trying to sell you extra vitamin and mineral supplements. When dealing with the diets of babies and children you should be in regular discussion with your GP/dietician/Consultant/Allergist to make sure your child is getting all the nutrients they need for proper growth and development.
Try to get your GP to prescribe anti-histamines, steroids and creams which will improve the symptoms from the allergies until they are under better control.
10. Pediatric food allergy and mucosal tolerance, A M Scurlock, B P Vickery, J O’B Hourihane and A W Burks – Mucosal Immunology (2010) 3, 345–354; doi:10.1038/mi.2010.21; published online 26 May 2010
11. Food allergy: when and how to perform oral food challenges, Sicherer SH, Pediatr Allergy Immunol.1999 Nov;10(4):226-34.
12. Food Allergy and Intolerance, J Brostoff and S J Challacombe, 1987
13. Food Solutions for Eczema, recipes and advice to provide relief, Patsy Westcroft
14. The Complete Guide to Allergies, P Brown, 2001
15. The Food Intolerance Bible, AJ Haynes & A Savill, 2005
16. Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI Task Force Report, Stapel SO, Asero R, Balmer-Weber BK, Knol EF, Strobel S, Vieths S, Kleine-Tebbe J, Allergy 2008, July;63(7):793-796