What are Food Sensitivities? How do they differ from Allergies & Intolerances?

Something you ate gave you  gas, cramps, pain or worse.

Although your biggest concern right now may be getting the pain or other symptoms to subside, you may also be wondering what the heck is going on. 

Is it an intolerance?

A sensitivity?

Or worse, an allergy to the food you just ate?

The world of food intolerances, allergies and sensitivities can be overwhelming and confusing.

If milk causes gassiness, is that an intolerance or a sensitivity?

Why do larger amounts of some foods cause problems while smaller amounts do not?  

What does it mean when a food “didn’t agree” with you?

How can you tell whether you’re experiencing an allergy, intolerance or sensitivity, and what is the difference?

I’ve got all those answers- and more- right here.

Let’s start with the basics.

A Quick Overview of the Digestive System

Food is eaten- we start breaking it down immediately by chewing. It gets further broken down by enzymes released in our saliva. The enzymes in the mouth (like a​​mylase) start breaking down carbohydrates right away.

From the mouth, food heads to the stomach where powerful muscles churn it and mix it with an acidic mixture of hydrochloric acid and enzymes known as gastric juice.

When the stomach has done all it can with the food (now known as chyme), it is sent to the small intestine.

The small intestine is made up of three parts- the duodenum (where most of the breakdown and digestion occurs), the jejunum and the ileum (absorption of nutrients occurs in these two parts). 

In the duodenum the food is hit with bile acids and digestive enzymes from the pancreas to break down food. There are a lot of specific enzymes designed to break food down, for example, lipase breaks down fat and lactase breaks down lactose (these enzymes end in “-ase”). Protein, fats and carbohydrates are all broken down here.

Food then moves through the jejunum where protein and carbohydrates are absorbed and then into the ileum where fats are absorbed.

Next up is the large intestine where minerals and water are absorbed (if too little water is absorbed we get diarrhea and if too much is absorbed and we get constipated).

It’s also where undigested carbohydrates like fiber are fermented by bacteria. While the small intestine is (well, should be) relatively free of bacteria, the large intestine has an abundance of bacteria that help digest nutrients like fiber and prebiotics. This helps keep the bacteria alive and thriving.

Food sensitivities, intolerance and allergies

So, what does all this have to do with food sensitivities, intolerance and allergies? Let's go through all three and look at what causes them in the digestive system.

What exactly is food intolerance?

When food makes it to the small intestine, enzymes help break it- lactase breaks down lactose, proteases break down protein, lipases break down lipids.

When your body lacks one of the enzymes to break food down or doesn’t produce enough of a particular enzyme to break down a food, that’s what’s called an intolerance. 

For example, if you have a lactose intolerance it means that your body doesn’t make enough lactase. So any foods with lactose (milk and foods made with milk) do not get broken down, instead traveling through the body undigested where they ferment and cause trouble.

Irritating? Yes.

Painful? Sure.  

Embarrassing, uncomfortable and nausea inducing? Yup, it can be.

But, life threatening? No.  

The bottom line: When the food in question is consumed, it is not properly digested (because there is a lack of enzymes) and, consequently, it ferments in the gut which causes bloating, gas and loose stools/diarrhea.

Main symptoms of an intolerance: Symptoms are confined to the gut and include bloating, gas, diarrhea or loose stools. 

Food intolerance does not involve the immune system, but allergies and sensitivities do. That makes them a bit more complicated.

To really understand what’s happening, we’ll do a brief overview of the immune response in the body.

(stay with me, I promise it’ll be quick!)

​​​A (very) brief overview of the immune response:

There are two parts to the immune system, the innate immune response and the adaptive immune response.

The innate immune response is your first line of defense, a hard wired immune response that’s fast acting, but broad and generally adapted to identify and destroy microbes and toxins, and differentiate them from human cells. It also includes physical barriers like your skin.

The body’s second line of defense is the adaptive immune response, a slower, but much more targeted system. Cells called T-cells find, process and identify specific antigens (foods, pollen, germs, toxins, etc.) as either “self” or “non-self”.

Once the body has identified the specific antigen and determined it is non-self, it replicates the white blood cells, antibodies and other immune cells needed to build an army to mount a defense against that antigen.

The body then releases chemical mediators designed to destroy the antigen. These mediators are ultimately responsible for you not feeling well.

After the attack the adaptive immune system produces cells to remember that specific antigen. These long lived cells keep a memory of the antigen so that the immune system can mount a more effective response against it if and when it’s encountered again (even if that’s years or even decades later).

The vast majority (approximately 70%) of your immune system is in your gut- so it makes sense that the foods you eat are going to bump into your immune system.

What happens when food meets the immune system?

Most of the time when you eat something, that’s it. That’s the end of the story. You ate something, your body digested it and everyone moved on. 

When nothing happens, it’s known as oral tolerance to the food. Your immune system recognizes that the food is not going to do any damage (the way a toxin or bacteria might) and allows it to go on it’s way without a full blown immune attack.

But, when you lose oral tolerance, for whatever reason, the immune system doesn’t play nice anymore.

What causes you to lose oral tolerance?

While no one is quite sure exactly what causes you to lose oral tolerance, there are a few things that seems to be connected to a loss of oral tolerance including stress and trauma, amount of food ingested and even the timing.

When you eat a food that you’ve lost oral tolerance to:

  1.  the immune system identifies the food as an invader and pegs it as a foe it wants to destroy.
  2. White blood cells, antibodies, complement and others are released to fight this food foe.
  3. Those cells release mediators (like histamine, cytokines and more- there are around 100 different mediators!) and before you know it, you’re feeling the effects- wheezing, diarrhea, pain, or even anaphylaxis.

This general process is the same in both allergies and sensitivities. However, the pathway involved is where things start to differentiate.

So, let’s get to it:

What is a food allergy?

An allergy is a Type I Hypersensitivity, often called an “immediate” hypersensitivity as it usually happens either immediately or within a few minutes. 

Here’s what happens: you eat a food. A peanut, for example. Your T-cells find it and decide it’s an enemy.

The T-cells trigger a reaction that causes a build up of the IgE antibodies that are specific to the peanut you just ate.

IgE on its own doesn’t cause a problem. It’s what happens next that gets you into trouble.

IgE finds its way to mast cells. Found throughout the body, including the small intestine, mast cells are your immune system’s big guns- they are very powerful but essentially kept under lock and key so they don’t do any accidental damage.

IgE acts like a key to that lock.

When IgE comes into contact with mast cells it “unlocks” the mast cell. So when it runs into the peanut you ate, the mast cell “degranulates” unleashing a host of chemical mediators- histamine, cytokines, TNF-α, interleukin 4 and others.

This mediator release results in symptoms like hives, trouble breathing or even anaphylaxis. 

Although much more rare than food sensitivities, allergies can be much worse and their reactions more obvious and immediate.

The bottom line: allergies involve IgE and mast cell degranulation. An allergic reaction can occur when as little as one molecule of the offending food is ingested, they occur immediately or up to 1 hour after ingestion of a food and can be deadly. Allergies are usually lifelong and the best way to prevent a reaction is to avoid eating the food you have an allergy to.

Main symptoms of an allergic response: symptoms range from mild to deadly and are usually limited to the respiratory tract, the skin and the GI tract, they can include vomiting, swelling of the tongue or throat, trouble breathing, wheezing, feeling weak or having a weak pulse, hives or even anaphylaxis (although that's much more rare). Food allergies affect 1-2% of the population. 

How are food sensitivities different?

Sensitivities follow different pathways. In fact, there are multiple pathways that trigger them (type III and type IV hypersensitivities).  

Food sensitivities are also known as delayed reactions. Unlike allergic reactions, they can take from 45 minutes up to 72 hours for symptoms to show up.

Also unlike allergic reactions, they can affect any organ in the body and are often chronic.

Here’s what happens:

You eat an apple on Tuesday morning. On Wednesday afternoon you find yourself with brain fog and diarrhea. Chances are your first thought isn’t the apple you ate a day and a half ago.

Food sensitivities can be hard to pinpoint because their symptoms are delayed. Even though your immune system is reacting, the impact is not immediate or overly obvious (like in an allergy).

So when your body mounts a full scale immune attack on that apple it’s hard to link it to the apple.

Since you haven’t identified the apple as the problem, you continue eating apples, and the immune response continues to occur and the inflammation goes from acute (happens once) to chronic (happening constantly). So you’re feeling lousy and you’ve got chronic inflammation, which can lead to a variety of nasty illnesses.

How do food sensitivities cause all this inflammation?

There are two ways that food sensitivities trigger inflammation in the body:

Type III hypersensitivity or a type IV hypersensitivity.

Type III hypersensitivities

Type III hypersensitivities are also known as a immune complex mediated hypersensitivity. 

Here’s what happens: 

You eat that apple. The apple (antigen) comes into contact with the antibodies IgG and IgM and they come together to form “immune complexes.”

Immune complexes are a normal consequence of eating, they are how your body clears out antigens- your body’s way of taking out the trash. Usually they are just broken down by white blood cells.

However, when there are too many immune complexes floating around they can overwhelm the system.

With the system overwhelmed the body cannot get rid of immune complexes quickly enough and they start to wander off.  They float around in the blood until they become lodged in tissue.

Once lodged in the tissue, the immune complexes draw the attention of your immune system- after all, something lodged in the tissue usually means bacteria or another enemy.

The immune system sets out to destroy this invader using a variety of white blood cells collectively known as “granulocytes.”  These cells release a variety of enzymes in an effort to eliminate the perceived threat, including inflammatory mediators.

The mediators (histamine, cytokines, prostaglandins, etc) cause inflammation in the tissue which leads to symptoms like joint pain.

Type IV hypersensitivity

A type IV hypersensitivity reaction takes the longest to manifest, sometimes up to three days (because of this they’re also known as delayed hypersensitivities).

Unlike the previous reactions, a type IV hypersensitivity reaction does NOT involve antibodies.

Instead, it involves T-cells. Which is why you may also hear it referred to as a T-cell mediated hypersensitivity.

Here’s what happens:

You eat an apple.

As it makes its way through your digestive system the apple meets antigen presenting cells. They grab a bit of the apple (the antigen) and present it to T-cells.

The T-cells identify the antigen as a threat and release mediators. They also bring in our old friends the granulocytes and other white blood cells to release their mediators as well.

It gets ugly.

All those mediators lead to inflammation, pain, migraines, diarrhea and more.

In fact, type IV hypersensitivities are most commonly linked to migraines and IBS symptoms.

A classic example of a type IV hypersensitivity is poison ivy. 

If you’ve ever encountered poison ivy, you know that it takes a while for anything to happen. The day you run into it you’re fine, but a few days later you’ve got a rash that itches like the dickens.

If you didn’t know you’d bumped into poison ivy you may have no idea what was happening. 

It’s the same with food sensitivities:

You may be fine right after eating a triggering food, but a few days later you’re feeling miserable. And unless you know which foods are causing an inflammatory reaction in your body, you’re left feeling sick, puzzled and no closer to eliminating the offending food.

(Want a leg up on learning about which foods are causing inflammation? The Mediator Release Test, or MRT can help).  

Of course, the amount of the food you eat is part of the puzzle as well. With both type III and type IV hypersensitivity reactions the amount you eat can play a role- they are dose dependent. Allergic reactions usually occur if even a single molecule of an item is consumed. 

Also unlike allergies (which are usually lifelong), food sensitivities can change. Once the inflammation in your gut has healed, previous food sensitivities may be reduced or even disappear.

The bottom line: Sensitivities involve the immune system and can take a variety of pathways. They  are often dose dependent and can take 45 minutes or up to three days before symptoms occur. Sensitivities can change based on exposure to antigens and levels of inflammation in the gut. Identifying them on your own can be a challenge.

Main symptoms of a food sensitivity: symptoms can impact any organ in the body. They range from mild to severe but are not deadly. Symptoms include diarrhea, migraines, IBS, malaise, generalized pain or excess weight. Food sensitivities affect 20-30% of the population. 

Interested in learning more about food sensitivities and how I can help you reduce inflammation and heal your gut? Drop me a line and learn about how I can help!


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