The terms food allergies, food intolerance and food sensitivity are thrown around synonymously in dietary discussions these days, without much understanding of what they actually mean and the differences between them. Understanding these differences can play a critical part in the success of elimination diets for your health concerns.
A food intolerance, is when the digestive system is unable to digest a food properly, which can then lead to symptoms relating to this maldigestion issue. Lactose intolerance is the most common example. When someone is lactose intolerant, they lack enough of the enzyme lactase which is responsible for breaking down lactose (milk sugar) for absorption in the small intestine. Normally all sugars are digested and absorbed in the small intestine. In this example, the sugar molecule (lactose) passes through the small intestine into the large intestine undigested and in "full sugar" molecular form. The large intestine is filled with yeast and bacteria (microflora). What happens to sugar (lactose) when it gets exposed to yeast in a warm moist environment? Almost instant fermentation which creates a gas and fluid production in the large intestine. This will ultimately lead to cramping, pain, gas, bloating and loose bowel movements. These are the common symptoms of a lactose intolerant reaction.
The key point to understand here is that the symptoms of the intolerance (gas, bloating, loose bowels) were caused by a food product (lactose) getting somewhere where it wasn't supposed to be undigested (large bowel) and it reacted with the microflora in the bowel and caused symptoms. At no point did the Immune system ever attack the lactose.
A food allergy, implies the immune system is reacting to and attacking the foods and causing symptoms through this immunological attack. This is a critical point to understand in order to begin to decipher your true food reactions. A food allergy can affect the digestive tract but it can also affect you anywhere in your body where the immune system is present.
The main differences between Food allergy reactions and Food intolerant reactions are outlined in the chart below.
Cause symptoms by improper digestion of a food
Symptoms are usually localized to the digestive tract
Symptoms often occur shortly after eating the intolerant food (Minutes to hours)
Symptoms usually resolve after passing of the intolerant food
Food Allergies / Sensitivities
Cause symptoms by an immune/inflammatory reaction to a food
Symptoms can occur in the digestive tract or anywhere else in the body
Symptoms can occur shortly after eating the food, or can be delayed by up to several days
Symptoms can persist for several days to weeks off one food reaction
If you have inflammatory issues anywhere in the body, it's critical that you understand the differences between food allergies and food intolerances. And it's also critical that you understand that if you have food related inflammatory issues in the body, they have to be associated with food allergies (immune related) rather than food intolerances. The immune system is what creates inflammation in this regard, food intolerances do not.
Two types of Food Allergies
Most people are aware of anaphylactic types of food allergies. A child with a peanut allergy is the classic example. These types of allergies are called type I hypersensitivity reactions. The keys to understanding this type of allergy is that they are mediated by a specific type of immunoglobulin (natural antibody) called IgE. These antibodies cause an immediate release of histamine in the affected tissue, and histamine causes an immediate inflammatory reaction in the tissue (swelling, redness, itchiness, welts, etc.) Symptoms of a type I allergic reaction always happen immediately after you eat the offending food. There is an obvious cause and effect with this type of reaction. When a child eats a peanut, their throat swells up immediately and they need an epi shot immediately to survive. It's very obvious the peanut caused the reaction.
There are three other types of hypersensitivity (allergic) reactions called types II, III and IV hypersensitivity reactions. These reactions involve completely different types of immunoglobulins called IgG and IgA. The key difference between these immunoglobulins and the type I IgE immunoglobulins, is that these antibodies cause delayed reactions in the body, sometimes delayed by up to a week to ten days. If you eat a peanut and have a type I reaction, your throat will swell up immediately and you will know immediately that you shouldn't eat peanuts again. If you eat a food and have a delayed type II, III, or IV reaction, you might not have a symptom relating to that food for several days to a week later. It's unlikely that you'll be able to associate a symptom one day, with a food you ate a week earlier. This is why people often never figure out their food related issues and never associate their symptoms with their diets.
The IgA and IgG components of the immune system are the same parts of the immune system that react against a vaccine. When someone receives a vaccination to travel overseas, they have to get the shot 1-2 weeks prior to travel in order for the immune system to have time to react to the vaccine and produce the antibodies to it. When these antibodies are produced against a food, the reaction is the same and it can take several days for the antibodies to be produced, travel back into the blood stream get out of the blood stream and into the tissue to cause the reaction.
Also important to understand, is how much food in takes to create a systemic IgA or IgG antibody reaction. When they give you a tetanus shot, they give you a 1/2 ml dose of the vaccine, and this will produce enough antibodies to go through the entire system and stay in your system for ten years. Your immune system only needs a micro dose of the offending food, to create a million fold antibody response against, that can stay in your system for weeks to months.
You can eat a food today, have a symptom caused by that food a week from today, and that symptom can linger on for several weeks... all after eating that one food item, one day. This delayed type of food reaction is extremely difficult for the patient to understand and makes it nearly impossible to try and figure out the association between their diets and symptoms associated with them.
Delayed onset allergic food reactions can also lead to food intolerances. Imagine eating a food today that you have a delayed response to. This reaction could come back and inflame the digestive tract a week later. This inflammation can affect proper enzyme production in the intestine, which can then lead to intolerances to the foods those enzymes are meant to digestive. You eat one food type today, it affects you digestive tracts ability to digest another type of food a week later. This becomes very confusing for the patient to figure out. Many times if you address the underlying delayed type food allergy, you can improve other food intolerances that you may be aware of.
Food Allergy Testing - Critical Comparisons
Understanding the different types of allergy testing is crucial to getting to the root of your food issues.
"Allergy Testing" in the conventional medical system refers to IgE Type I Immediate Hypersensitivity Testing. This is what most people would refer to as "Scratch Testing". This testing will only identify allergens (food, environmental, etc) that you have a Type I sensitivity to. The hallmark and most severe form of this type of allergy would be an anaphylactic reaction such as the peanut / throat swelling reaction mentioned previously. Type I IgE allergies can come in other symptomatic form however. It can happen in the stomach and bowel, or welt / hive reactions in the skin. This is why they scratch test through the skin.
The seldom do scratch testing for food allergies for some obvious reasons. The Type I allergies cause symptoms immediately after eating the offending food, so it's very easy to figure out the food that caused the reaction. If you eat a peanut and almost suffocate from it, you don't need to go to the doctor, get referred to an allergist, go to the allergist and have them put peanut on your arm to see if you have a peanut allergy. You already know.
IgG and IgA antibodies are produced by what is a called a DELAYED hypersensitivity reaction (as compared to Immediate for IgE). As mentioned earlier these antibodies are produced in a delayed manner and therefore the symptoms they cause can show up several days after eating the offending food. This makes it extremely difficult for patients to figure out the food that causes the symptom.
The only testing that is available through the conventional medical system currently for IgG or IgA food antibodies is for Celiac disease and this tests for Tissue Transglutaminase Antibodies (tTG-IgA) associated with the protein gluten and gliadin. There are currently no conventional medical tests available to test for IgG or IgA antibodies to ANY OTHER FOOD aside from Gluten or Gliadin.
It stands to reason that if a person could produce an IgA antibody to gluten which cross reacts with a tissue in the bowel, another person could produce an antibody to another food protein and have tissue cross reactions in other tissues in the body. This is just logic and common sense.
It's also critical to understand that you can have one type of reaction to a food (for example an IgG reaction to Dairy) but when scratch testing is done for the food it will come back negative. This is because of the different type of antibody being tested! Depending on a persons genetic and immunological make up, anyone can produce any unique combination of IgG, IgA and IgE food antibodies.
Conventional Medical Views on IgG and IgA food antibody testing.
We typically hear three main arguments against IgG and IgA food testing from the conventional medical world.
First, they refer to IgG and IgA food issues as being more "sensitivity" than allergy which somewhat downplays their importance. They say IgE responses are true allergies (like the anaphylactic reactions) and are the critical ones to identify. They ARE absolutely critical to identify but the IgG and IgA antibody reactions can be just as critical.
The IgG and IgA food reactions aren't referred to as true "allergies" and are just called sensitivities. This is actually false. The definition of an "allergy" is a damaging immune response by the body to a substance such as pollen, fur, dander, a particular food, dust, or environmental particulate to which it has become hypersensitive. This can include a white blood cell, binding to an antigen (something you're allergic to) and producing an antibody response against it. IgE, IgG and IgA antibodies are ALL produced in this manner. Also by definition the IgG and IgA reactions are considered delayed HYPERSENSITIVITY reactions. So by technical definition, these delayed antibody reactions ARE true allergies, they are just a different type of allergy.
The second argument we hear against these types of tests are they are not "medically validated" test procedures. There are many types of "food tests" out there which I would agree are not medically validated. But IgG and IgA testing is typically done by a procedure referred to as ELISA testing. This stands for Enzyme Linked Immuno-sorbant Assay. This is the exact same procedure that conventional medical labs used to identify celiac/gluten antibodies and also many other pathological antibody tests such as thyroid / adrenal auto-antibodies, viral antibodies and many others. So the argument that an ELISA test isn't medically validated, basically says many of the conventional testing that are done, including celiac testing, aren't medically validated. That argument basically collapses in on itself!
Finally, many suggest that this testing only identifies what you have been eating, and not what you are actually allergic/sensitive to. In other words whatever you have been eating will show up on your test. Many patients express that concern to me before having the test done. When their test results come back they realize this isn't a valid concern. There will be many different foods that they eat on an extremely regular basis, that show negative responses.
Another way to explain this would be that if their argument was correct, than everyone who eats gluten would produce gluten IgA antibodies. Yet many patients who eat gluten and get tested for celiac disease have negative responses (no IgA to gluten/gliadin) on their tests. According to the argument, this shouldn't be the case.
Another example could be with peanuts and anaphylactic reactions to them. They are associated with an IgE antibody reaction against the peanut. If our systems just produced antibody to whatever we ate as the previous argument suggests, then everyone who eats peanuts should have anaphylactic reactions to them, and this isn't the case. Many people can eat peanuts and not produce antibodies against them. So this can happen with IgG and IgA food allergies as well.
To summarize, conventional medical testing focuses on acute hypersensitivity reactions (IgE) to foods when they do "food allergy testing" but aside from celiac disease, they don't have testing for any other type of delayed hypersensitivity reactions to any other foods, and therefore they suggest these allergies don't exist. They do. Please refer to the second article on this blog to see many examples of these types of allergy profiles.
Also they say the IgG and IgA allergies are only sensitivities and do not play significant roles in people health compared to acute IgE allergy responses. To their point, IgE allergies can be acute and dangerous and should be identified. But the delayed IgG and IgA allergies can be just as impactful on your health. They just impact it in a delayed/hidden and long term chronic inflammatory sort of way.