Skip to main content

Food Allergy or Sensitivity – What’s The Difference?

Over the next few weeks I will be addressing the topic of food allergies and food sensitivities; a subject I address every day as both a physician and mother.  As a physician I help patients identify and manage their food allergies and sensitivities. As a mom, I live with deadly food allergies on a daily basis as my eldest son has  an allergy to dairy and nuts that is so severe that even the smallest exposure could kill him.

Food Allergies and food sensitivities are both reactions caused by the immune system in response to certain foods, they can both cause inflammation and distress in the body. However, a true food allergy can produce symptoms strong enough to cause death.

The difference lies in the kind of immune reaction that occurs when you eat the particular food that is causing the problem.

The Immune System – How does it Work?

The immune system has different tiers of defense in order to keep our bodies safe from foreign invaders like bacteria and viruses. White blood cells, the cells of the immunes system, are divided into 5 types: Neutrophils; Eosinophils; Basophils; Lymphocytes and Monocytes. These white blood cells have many roles that combine to defend and protect us, and keep us healthy.  One of the first lines of defense are scavenger cells, known as Macrophages (a type of monocyte) that circulate in the blood looking for foreign proteins known as antigens, rather like Pacman searching for food in the computer game. In this case, the Pacman macrophages are searching for substances that aren’t supposed to be there and gobbling them up to protect us from them. When the macrophages detect an antigen they release a chemical message that is sent to the immune tissue around the body telling it to attack. Macrophages are therefore, often the first cells of the immune system to detect a foreign invader and start the cascading effect of our immune system.

When a foreign protein (antigen) is detected, the immune system stimulates white blood cells, specifically lymphocytes, to produce antibodies whose job it is to attach the antigen and remove it from the blood. Antibodies are produced from a lineage of cells in our immune system called B cells (a type of lymphocyte) which can create a memory of each foreign antigen so that the next time we are exposed to it our immune system can quickly kick into gear and defend us against this foreign invader. This mechanism gives us immunity against the bacteria and viruses we have already been exposed to.

The problem occurs when our immune system identifies the food we eat as a foreign antigen and launches an attack (or immune response) on it. There are four possible immune reactions but, for the purpose of this article, I will focus on just two of them: Type 1 Immediate reaction and Type 3 delayed reaction.

The two main antibodies responsible for reactions to food are IgE (type 1 reaction) and IgG (type 3 reaction). Type 1 is responsible for allergic reactions while type 3 causes food sensitivities. Let’s look at each of them in turn.

 Type 1 IgE Mediated Immune Reaction

An IgE mediated reaction is what is known as a true allergic reaction. IgE antibodies have the potential to trigger a powerful inflammatory response. Exposure to a substance that you are allergic to (in this case a particular food) triggers the immune system to release histamine which causes the inflammation.  For people with food allergies this powerful response most commonly includes hives, swelling of the lips, tongue & throat, asthma, breathing difficulties and vomiting. It is the swelling of the throat and the consequent difficulty breathing which is one of the main causes of death in people with a Type 1 IgE mediated sensitivity. This type of response is called an anaphylactic reaction and can also occur in response to insect bites and certain drugs. Anaphylactic reactions can occur within seconds of eating an allergenic food, which contributes to its deadly and violent effect.

Type 3 IgG Mediated Delayed Immune Reaction

This type of reaction is referred to as a food sensitivity and not a true “Allergic” reaction. It is a delayed reaction that can occur anywhere from a few minutes to a few days (up to 72 hours) following exposure to a particular food.  IgG is the most common type of antibody found in circulation in the blood and is therefore also the most common type of food reaction. In my practice I find that most patients who have food sensitivities have at least 2 or 3 foods that they exhibit symptoms from. These symptoms can occur anywhere in the body and can vary wildly. Possible symptoms include:  digestive symptoms, headaches, muscle or joint pain, skin issues, anxiety, depression or difficulty with fertility just to name a few. These symptoms are triggered by an immune response that can cause inflammation anywhere in the body.

An Ig E mediated allergic reaction is so  immediate with rapidly progressing symptoms that people are aware of the reaction and seek medical care at the time of the symptoms. The problem with identifying food sensitivities is that, because symptoms tend to be delayed, it can be hard to figure out why you are having a headache or stomach pain two days after eating a problem food.

How Can I Tell If I Have a Food Allergy or Sensitivity?

A simple blood test, done by your doctor, can tell you whether you have IgE or IgG mediated food reactions. Your blood sample is sent to a lab where it is mixed with certain foods to see if there is a reaction. The total amount of circulating IgE immunoglobulins in the blood can also be tested which gives you an idea how much of the antibody is being produced (the more antibodies you have, can be correlated with the strength of the allergic reaction). This can be monitored to see if levels, and therefore allergic reactions, reduce over time.

IgE reactions can also be tested using a skin prick test, usually at an allergist’s office.

Both tests are usually done as panels that test the foods that most commonly produce either an IgE or an IgG mediated food reaction. Of these two tests, it has been my experience that the blood tests are easier on the adult or child having the test done.

What Do I Do After I Find Out My Results?

Once you know which foods are causing the problem, you can eliminate them from your diet. If you find you have a true food allergy you will need to carry an epi-pen (to give yourself an adrenaline injection to stop an anaphylactic reaction) and Benadryl (an anti-histamine) on you at all times in case of an allergic exposure. If you discover you have food sensitivities it is recommended that you eliminate the specific foods for 120 days to allow the levels of antibodies circulating in your blood on the hunt for those foods to decrease. After 120 days you can start to reintroduce the foods one at a time, every 2 days and watch for symptoms.

Living with allergies and food sensitivities is hard. It can even be hard to get your mainstream doctor to do the right tests to find out what’s going on. Because of this, I have put together a comprehensive 5-month Food Sensitivities/Allergies Program that includes the relevant tests and a bespoke program of support to help you regain control of your life. You can access this no matter where you are in the world, make an appointment today to find out more.

Next time I will be talking about how to spot food allergies in children – to receive it straight to your inbox please subscribe to this blog using the subscription box on this page.

I’d love to hear your thoughts and experiences about the effect food allergies and food sensitivities have had on your life, your tips for living with allergies and how life has changed since you got rid of your food sensitivities. Please leave your comments or questions in the comments box below.

Health is a process and at A Path to Natural Health my goal is to guide my patients along their journey to health.


Dr. Maura Scanlan

You Might Also Enjoy...

Is Candida Making You Fat?

Naturopathic Doctor, Maura Scanlan explains how Candida can cause weight gain that doesn’t respond to normal weight-loss programs: she suggests a diet that works.