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It is important distinguish between Food Allergies, and Intolerance and/or Sensitivities, and as much as we know or believe to know more clarifications come up.
During my internship in hospital after my degree in Biology, I have had the opportunity to work in a laboratory sector where allergy’s tests were performed on serum to detect the immunoglobulins responsible for allergic reactions, the IgE, and those for intolerances, or better sensitivity as IgG and IgA and which in case of wheat compounds, gluten and gliadin are responsible for celiac disease, these tests were called PRIST and RAST for allergies and AGA for gluten sensitivity, for I have a little bit of knowledge in this field along with the studies that have accompanied this part.
Then I have learned more from Dr. Peter D’Adamo, the Blood Type Diet founder; one of his books on allergies was my first approach to his science and to his focus on lectins in foods and ways the body reacts, antibodies productions to foods’ antigens, or allergens and of course, the involvement of blood types in this case. Then later from Dr. Tom O’Bryan, the gluten sensitivity expert who covers in his books, webinars, and public speaking great part on food sensitivities and related connections with health and diseases, inflammation, leaky gut, importance of health of microbiome, immune system, the autoimmunity process, and the different theories in regard, and much more.
But despite of all and because the material around is a large amount among books, courses, articles, etc., alternatively, I refer to the internet when in search of clarifications and validations, and for quicker results, and here is how I have found in the middle of a new confusion.
There were several articles in regard, as for everything we look on internet, but I concentrated my attention on two of these, the first one did clarify and refreshed what I already knew, but the second one, actually, a you tube video coming from a reliable source appeared to contrast everything in regard of IgG and food sensitivities, and paradoxically confirming something that I was always wondering myself.
The first article from a certified nutritionist gives a good understanding among the differences and provides accurate information.
The author, Dr. Mary Ellen, defines Food Allergy as hypersensitivity of the immune system to foods with production of IgE or immunoglobulin-E, Food Sensitivity as immune delayed reaction and which manifests with the production of IgG and IgA, and finally Food Intolerance as a non-immune reaction to foods.
Then she gives a brief explanation of what antibodies or immunoglobulins are as products of the immune system (lymphocyte B) against invaders, and that body makes different immunoglobulins to combat different antigens. There are five classes of immunoglobulins, but three are those involved with food reactions, and they are:
Immunoglobulin E or IgE, Immunoglobulin G or IgG, Immunoglobulin A, or IgA
IgE allergies are immediate responses to an antigen that has entered the body. After being exposed to an allergen, IgE antibodies attach to mast cells, where they stay until the next exposure to the food which has caused the allergic reaction. At a next exposure, the IgE antibodies stimulate the mast cells to send out histamine and other compounds cause of symptoms like inflammation, swelling and itching.
IgE food allergies -she reports- can decrease over time if an individual’s health improves. Dr. D’Adamo, instead, was talking of decreasing with age. The stronger the immune system and the healthier the gut, the better the body will be able to tolerate accidental exposure. Symptoms of an IgE allergy usually appear within seconds or minutes and can include swelling/inflammation, hives/rash, itching skin, difficulty breathing, throat tightening anaphylactic shock in severe cases.
IgE tests are performed as part of an initial screening for allergies or for confirmation of an allergy. This can be done by skin prick or patch testing which measures how much IgE is present in a person’s blood, or with test on serum-blood as I was mentioning previously.
IgG food allergies are delayed food allergies. They are often called food sensitivities.
With IgG reactions– she assesses- the immune system produces IgG antibodies which can lead to inflammatory processes. Symptoms for IgG reactions can appear up to three daysafter the consumption of a food. It is not always easy to identify exactly which food causes problems because of the delayed appearance, therefore tests or an elimination diet can help. Dr. O’Bryan, for example, at this regard, keeps repeating- as he stresses on different other part in regard of this matter- that people with allergies are “lucky” because they know what food or allergen can be a problem, while people with sensitivities cannot.
Elimination of IgG-positive foods, under her observation- and of other nutritionists- can often improve symptoms of irritable bowel syndrome, autism, ADHD, cystic fibrosis, rheumatoid arthritis, and epilepsy, according to numerous clinical studies.
IgG antibodies– she continues- lead to inflammatory processes and are not associated with the release of histamines, for this reason there are not immediate hypersensitivity reactions. And this is what the majority of naturopaths and integrative doctors believe and sustain.
Symptoms of an IgG reaction can include anxiety, depression, bloating/gas, diarrhea, constipation, acid reflux, joint aches, fatigue, mood changes, hyperactivity, loss of breath, weakness, brain fog/memory issues, and certain conditions- she believes so as others in this field- could derive from food sensitivities such as arthritis, migraines, ear Infections, eczema, sinusitis, asthma, colitis, irritable bowel syndrome or IBS.
She also comments about the consequences of these reactions and of the damages on the intestinal wall and the emerging of leaky gut. With intestinal permeability the intestinal wall becomes porous letting food particles, toxins, and bacteria flow into the bloodstream and causing the immune system to react and trigger inflammation and changes into the gut. Chronic, prolonged inflammation and toxicity can be a cause of autoimmune disease and other related disorders, as I personally keep bringing up, so as the doctors I refer.
For this nutritionist, as for the most I believe, it is often difficult to determine exactly which food cause problems because of the delayed appearance of IgG symptoms, and because of this, an IgG test, or Food Panel test, is the best way to find out foods to which we are sensitive, but it does not look like for allergologists as I will explain in a few.
IgA reactions are not related to food allergies and sensitivities, but they are involved with intestinal permeability. IgA, or secretory IgA are found in high concentrations in the mucous membranes of the respiratory and gastrointestinal tracts. Secretory IgA provide protection against potentially harmful microbes, they are the body’s first line of defense against bacteria, food particles, parasites, and viruses. Chronic stress, frequent antibiotic use, overload of foods like soda, coffee, alcohol, or sugar can thin the lining of the gut.
She also mentions a Secretory IgA test, called SIgA test to see how strong or thin the gut-lining is. This will show a person’s ability to defend against infections, allergies, and food reactions as well as provides guide for next steps in treatment of health issues.
Food intolerance can cause some of the same symptoms as a food allergy/sensitivity, for it is easy to be confused. Whilefood allergies trigger the immune system, food intolerances do not. Food intolerances are usually caused by a deficiency or absence of an enzyme neededto digest and process a food.
She mentions two examples in regard, lactose intolerance where people do not have enough of the enzyme lactase necessary to break down the sugar lactose found in cow’s milk, and histamine intolerance that could be due to lack of the DAO or HNMT enzymes that both lead to an excess of histamine.
People with food intolerance may be able to prevent issues related by taking the digestive enzymes that are missing. Histamine intolerance is a little different because of the buildup of histamine. She suggests better to stay away from foods that release histamine until this one level is decreased.
She then concludes saying that food intolerances do not have a specific blood test because the immune system is not involved, and immunoglobulins will not be present in the blood, and that some people are more susceptible to intolerances because of genetic polymorphisms -variations in DNA called SNPs or single nucleotide polymorphisms- In the case of histamine intolerance, DNA testing could be done to see if predisposed to impaired histamine processing. She mentions three main genes involved in processing histamine HNMT, DAO, MAO.
“Dirty Genes,” a book by Dr. Ben Lynch, who is the expert in SNPs and methylations and histamine sensitivities gives a good understanding in regard of SNPs and genetic variations and more, I refer to him and to his book in regard of all of this as more times mentioned in my blogs.
Dr. David Stukus, pediatric allergologist, is the specialist that I was talking about and that has created the confusion to myself. This doctor in a you tube video comments about the validity of Food Panel testing and values of IgG in regard of intolerances or sensitivities.
For his definition Food Allergies are dangerous immediate reactions to a food and that manifest with IgE production, while with Food Intolerances or Sensitivities the body cannot process or digest a food, and this can cause uncomfortable but not dangerous symptoms. Classic food intolerance is the lactose intolerance due to the lack of the enzyme that breaks down the lactose and that can cause, abdominal pain, bloating, gas, and other symptoms, especially if eating too much of that food; other foods may also cause brain fog, fatigue, and joint pain.
He thinks that no tests can be reliable and that tests that claim to diagnose food sensitivities are available as IgG food tests. These tests report IgG levels toward multiple foods declaring that the remove of the food responsible of raising the IgG level can improve the symptoms or can even reverse conditions like IBS, autism, rheumatoid arthritis, or epilepsy.
He sustains that there are not scientific studies in support of this and that:
“The presence of IgG is a normal response of the immune system to exposure to food,” and that “Higher levels of IgG4(a sub-class of IgG) to foods may simply be associated with tolerance to those foods”
He then continues that due to lack of evidence, many organizations including the American Academy of Allergy, Asthma, and Immunology have recommended against using IgG testing to diagnose food intolerance or sensitivities.
No words at this point, this is up siding down every believe around, maybe I just heard this for the first time, probably this is already common in the conventional medicine and functional medicine, but the believes are different and divergent.
It is true that antibodies are a rection to an antigen and that in this case is a food, or allergen, that IgG are the evidence of a past contact, or exposure, and that they testimony chronic infection, and that when there are antibodies against foreign agents that means that the immune system is reacting or has reacted and that all of this will cause a cascade of events that will lead to inflammation and from here to an infection or something else.
How come an immunologist/allergologist does not consider this, I am feeling confused myself and certainly aware that has been time that I am not in the field anymore, or practicing laboratory for I do not feel so confident to support or to argue, but I really hope that the experts will give more clarifications in regard, and especially this doctor and his philosophy of thought.
Wishing a Happy and Healthy New Year!
Thanks For Reading
Mariarosaria M.
Sources:
” Food Allergies and Sensitivities: The Difference Between IgE and IgG reactions http://www.vnutritionandwellness.com/food-allergies-sensitivities
“Unvalidated Food Allergy Testing” by Dr. David Stukus, MD http://www.aaaai.org
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The Emerging Science 
great info! wishing you joy & success here for 2022!
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Thank you! You are always very nice.
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likewise 🙂
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