Many people talk about these like they are the same thing. But there are some subtle differences that are helpful to know about. 

We’ll start with intolerance. You are probably already familiar with one that we talk about a lot…Histamine Intolerance. 

An intolerance is what happens when the body isn’t able to get rid of something fast enough. Histamine, salicylate, and oxalate issues are intolerances.  

With histamine intolerance, we often talk about this using a sink metaphor. Your “sink” might be small, or it might be full.  

The sink is how much histamine (or salicylates or oxalates) your body can keep up with at any given time. 

With this metaphor, water pouring into the sink is the amount of histamine, salicylates, or oxalates you are consuming or producing in your body.  

Then at the bottom of the sink there’s a drain. The drain is your body’s way of getting rid of histamines, salicylates, and oxalates. You do this mostly through special enzymes in your body and through excretion in urine, stool, and sweat. 

So, when you add more than the sink can drain, the sink overflows. 

Basically, intolerances happen when your body can’t keep up with the overflow. For example, when histamine levels build up and are more than your body can handle, that’s when you can get Histamine Intolerance.  

Symptoms for each type of intolerance vary. Even from person to person, they can be different. With Histamine Intolerance common symptoms can include itching, headaches, digestive issues, anxiety, fatigue, and sleep problems. 

Common symptoms of Oxalate Intolerance can include urinary tract pain and urgency, joint pain, muscle pain, painful bowel movements, rashes, and mood swings. 

Salicylate Intolerance symptoms, on the other hand, can show up as ear ringing, trouble breathing, headaches, congestion, stomach pain, and GI issues. 

FODMAPs are another type of intolerance. This is where your body can’t break down certain fibers found in specific fruits, some vegetables, some grains, lactose, and sugar alcohols. This can show up as bloating, gas, intestinal pain, constipation, and/or diarrhea after eating these foods. 

Intolerances can trigger an immune reaction for various reasons. But they aren’t caused by an immune reaction like food allergies or sensitivities. 

Let’s look at allergies next. 

Food allergies aren’t nearly as common as sensitivities. Food allergies occur in only about 2-5% of the population. With an allergy, your immune system treats the food you are allergic to as a harmful invader. A food allergy triggers what’s called an IgE immune reaction. You might know this better as an anaphylactic reaction.  

These can be fairly serious. 

An anaphylactic reaction is usually immediate and severe. Common reactions are hives, trouble breathing, throat closing, fainting, fast heartbeat, anxiety, and vomiting or diarrhea. An allergy can be a concern for years, or it can be lifelong. 

With a food allergy, even the smallest amount of a food can trigger a response in some people. For example, someone with a severe, true IgE peanut allergy may not be able to travel on an airplane where someone several rows away might be eating peanuts. 

There are also people with milder IgE food reactions that they may not know about, but can be triggering mast cells. 

The best testing for IgE food allergies in people with mast cell issues is blood testing (not skin prick testing). 

A Gluten allergy is a food allergy that can cause severe and immediate symptoms such as hives, difficulty breathing, and diarrhea. This would be an IgE form of immune reaction to gluten.   

Food sensitivities, though, are much more common. Let’s look at this next. 

Food sensitivities are a different kind of immune response. With an allergy, an IgE response is triggered. With food sensitivities, other immune responses, like IgG, are triggered. 

These responses often happen when the gut lining is leaky and food particles leak into the blood stream. This can cause delayed reactions that can be hard to pinpoint. They can cause a ton of problems, but typically a sensitivity isn’t life-threatening in the way allergies can be. 

Food sensitivities often develop with leaky gut. When the gut lining is leaky, small food particles can get into the blood stream where they don’t belong. Then the immune system comes along and creates what are called IgG antibodies to the foods seen as a threat.  

IgG food sensitivities can be tested with blood testing. Some tests are better than others, though. Generally, the bests tests are available through your health care provider.  

These results also need to be reviewed by your health care provider who can help you put together a plan. Many people with Mast Cell Activation Syndrome have dozens of IgG food sensitivities.   

It can be detrimental to cut all of them out. Sometimes rotation is a better idea. And if there are several IgG positive foods, then it may make sense to work on the underlying causes of the leaky gut instead of whittling your foods down to very few. 

So, get help before you reduce every IgG positive food. 

Gluten sensitivity (non-celiac gluten sensitivity) is the most common form of problem with gluten. It can create some of the same symptoms as an allergy or Celiac Disease such as diarrhea or abdominal pain. But, it typically isn’t life-threatening like an allergy can be. And it doesn’t cause visible damage to the gut like Celiac. But it can still cause a lot of problems…especially if you have Mast Cell Activation Syndrome or Histamine Intolerance.   

Sensitivities are mostly what we’re talking about in this post.  

However, when we talk about Gluten, we should mention Celiac Disease. Let’s briefly look at the differences between Celiac Disease and Non-Celiac Gluten Sensitivity.