When most of us think of the word "allergy" we are thinking of a systemic immune response, or at least an immediate and visible reaction. For myself as a child, allergies meant allergic rhinitis - streaming eyes, runny nose, and atopic reactions (rashes, usually itchy) to almost everything it seemed. My bedroom floor was regularly hoovered, as were the curtains and the bedding was washed every few days. My teddy lived in the freezer during the day for some time too to help eradicate the house dust mites I was so allergic to. I was on Beconase inhalers for years and we probably should have taken out shares in Piriton... However there are different kinds of allergic responses.
IgE MEDIATED RESPONSES
The above are all IgE mediated responses. True allergies, and allergies you can test for. IgE is an immunoglobulin. An immunoglobulin is "any of a class of proteins present in the serum and cells of the immune system, that function as antibodies". There are five subclasses of immunoglobulins, explained here far better than I could. DO read that link, it's the single best source I have found for non medics to explain your immune system and how it is classified.
IgE responses can be tested for - in Skin Prick Tests, and in RAST blood tests. The former have to be properly done to be accurate and reliable - we spent two years carting around an epipen for our second son who was allegedly allergic to peanuts - only to be retested a couple of years later (properly) and be told this was in fact rubbish. (Whilst some allergies can be outgrown, this is almost never the case with an IgE reaction to peanuts.) RAST blood tests are interesting, because they cannot in fact measure the severity of the reaction, the higher the number the higher the exposure rather than severity of response, so an older person would be expected to have a higher count.
NON IgE MEDIATED RESPONSES
You may think that a non IgE response would have to be what is termed an intolerance, but you would be wrong- along with an alarming number of health professionals I have encountered! An intolerance does not involve the immune system at all. A non IgE allergy is also known as a Type IV sensitivity, or cell mediated response. It is a local reaction and is rarely possible to test for. Gut allergies are delayed hypersensitivities, which is why food allergies are so traumatic and difficult to manage, requiring strict exclusion diets to determine responses to possible triggers. Imagine an eczema reaction in the gut - it's a localised response to an allergen (or a false allergen which the body responds inappropriately to) and causes a localised problem - no anaphylaxis, no outside response (although IgE responses are often present in addition in those with gut allergies) and is very difficult to diagnose.
Gut allergies are always responses to proteins, protein molecules are those the immune system responds to. Problems with carbohydrates/sugars such as lactose intolerance are not (as far as I know!) allergies.
Now imagine that patch of inflamed, irritated gastrointestinal tract - if your skin has a patch of eczema it is less supple, less flexible, cannot function at its best. Gut tissue is the same - it cannot function as well as it becomes inflamed. Inflammation ANYWHERE in the GI tract can cause symptoms anywhere else along its length. So, you can have reflux (which is only ever a symptom, be it from food allergy, obesity, muscle disease, ligament laxity, developmental delay etc) constipation, vomiting, diarrhoea, trapped wind, acute pain, chronic pain, bloating, wind - all from gut inflammation due to a localised allergic response. All too often I hear of children and adults with reflux symptoms, who have an upper endoscopy ("scope" where a camera is used to look down your throat as far as your stomach, and sometimes down to the small intestine below but only a small way down.) and a ph study which is negative and they are told there is no inflammation, no problem. It's happened to us too, my daughter was fobbed off for years until someone bothered to look lower and found inflammation and ulceration, causing the reflux further up. Bowel inflammation can, and does cause reflux. There are often other clues but sometimes it is that simple.
What is so concerning is the difficulty so many parents are having in getting appropriate care for children with clear reactions to food. Any parent with a child suffering from food allergies will tell you how their child reacts - yet if skin prick tests and RAST tests are negative many doctors come to the conclusion there cannot possibly be an immune response. Some doctors prescribe patch testing, which does indeed show delayed responses, but only on the skin. If it is only your gut tissues which is reacting, they are not going to be particularly helpful.
Another useful test is an serum IgA blood test. Immunoglobulin A is the major antibody found in the membranes of the respiratory and gastrointestinal tract. The second most common immunoglobulin in the human body, IgA can also be found in tears, saliva, mucus, and colostrums. IgA is one of the most important immonoglobulins in local immunity. Interestingly those with gut allergies often have low IgA levels, and in those who outgrow their gut allergies their IgA levels often rise approximately 6 months before such improvement become obvious when closely monitored. This is another reason why the antibiotic Azithromycin is so successful as an anti inflammatory agent in the gut, because of its role in the absence of IgA.
REFLUX and GUT INFLAMMATION
There is a huge surge in babies with reflux in the West, which is often due to gut allergies such as Cows Milk Protein allergy or reactions to other food proteins. It is often outgrown by the age of one but in those whom it persists into childhood underlying causes need to be investigated - any paediatrician should tell you that. The gold standard test for reflux used to be a ph study, measuring the ph at the top of the stomach. However, reflux caused by bowel inflammation is unlikely to be acidic unless the stomach contents at that time are acidic! Reflux caused by bowel inflammation is more likely to be alkaline, and shows up best using an impedance study or pressure test, used in conjunction with a ph probe. Gut inflammation will reduce gut functionality and therefore cause pressure changes along the GI tract.
No one is exactly sure why there is almost an epidemic of gut inflammation in the West. Many will tell you it is the overuse of antibiotics, the increasing prevalence of GM foods, over production , pesticides, chemicals etc but the truth is we just don't know. One thing is certain though that gut allergies are on the rise. In America there has been a surge in the number of diagnosed Coeliac Disease cases - interestingly Coeliac is another delayed hypersensitivity, as is Chrohn's Disease. Eosinophilic Disease is also thought to fit into this category which makes it so very difficult to treat and manage.
FOOD ALLERGIES AND BEHAVIOUR
Until quite recently there was little understanding of the way gut allergies worked. Recent research at Great Ormond Street has shown how neurotransmitters in the gut sit next to mast cells which are responsible for these local gut reactions. As these mast cells degranulate they release huge quantities of toxins which cause a local pain feedback cycle. They are also soaked up by the neurotransmitters and enter the central nervous system. This is thought to be how food allergic reactions cause the behavioural issues we often see in children with food allergies and could also explain why the casein and gluten free diet for Autism might just work for some children, who in fact display ASD type behaviours due to delayed gut hypersensitivities.
Local gut reactions also cause an increase in histamine levels which make the gut wall more permeable. Anyone heard of Leaky Gut Syndrome? Something I thought highly "alternative" and improbable until I was immersed unwillingly into the world of gut allergies. What is more concerning is recent GOS research which is supporting the theory that the blood brain barrier is permeable (as is the gut) when local immune activity is present. Teething can also precipitate this permeability by raising histamine levels. There is in fact current speculation as to whether a highly allergic child - whether IgE or non IgE - and/or one who is actively teething should have their vaccines postponed/delayed. This is similar to the theory postulated by Andrew Wakefield, whose totally flawed study left him hung out to dry but which buried the real message that timing is actually important with vaccination and that the links between the gut, Autism and vaccination might well have more to do with histamine and gut permeability than multiple vaccination programmes.
Lastly what i find particularly interesting coming from an EGID perspective is that several Autoimmune diseases are also Type IV hypersensitivites. Hashimoto's Thyroid Disease (which I suffer from) Diabetes Type 1, Arthritis... all the same type of reaction by the body. There are extremely strong links between gut allergies, immune profiles and autoimmune diseases. My children also have low IgM and IgG levels - again, common in those with autoimmune disease, but also caused by gut inflammatory conditions!
So despite being non-IgE, impossible to test for allergies, the immune profile of these localised, delayed hypersensitivities is perhaps more profound than the more obvious, recognisable IgE responses we are all more familiar with. I think it's about time the medical profession sat up and took notice of the autoimmune time bomb in the West and the surge in gut allergies - REAL food allergies so many people (and particularly so many children) suffer from ARE relevant, and health professionals in the twenty first century have a responsibility to take them very seriously indeed.
DISCLAIMER - I am not a doctor, the information above I have ben told, read and learned over the years. The opinions are not only my own, but it must be stressed that this is a Blog not a medical document and whilst knowledge and opinion is useful you must follow the advice of your/your child's doctor. By all means discuss the above, I have carefully referenced the information but I am not medically trained. I support and endorse vaccination programmes - having children with reduced immunity I know the importance of herd immunity and prevention of disease. I always endeavour to research issues affecting our family however and take each intervention as an individual case.