What’s the Difference Between a Food Allergy, Food Sensitivity and Food Intolerance?

What is a food sensitivity?

This is a question that comes up a lot in my practice. And before I dove into the nutrition world, I didn’t know the difference either! But in order to properly navigate nutrition and find the right diet for you, it’s important to know the difference.


Food Allergies

A food allergy is when your body produces the antibody IgE after consuming the food you’re allergic to, and people who have a food allergy are usually well aware of it. The allergic response usually happens within 15-30 minutes of eating the food you’re allergic to, and reactions are usually how you think of allergic reactions: swelling, throat closing, hives, congestion – reactions usually involving the nose, throat, lungs, or skin. With each exposure, these reactions can become more severe. Common IgE allergens are things like tree nuts, peanuts, wheat, soy, shellfish, eggs, and dairy. Often these are lifelong, but in certain cases it’s possible for these allergies to improve, but it should always be under the care of an allergy specialist.


Food Sensitivities

Now this is the realm where I hang out, and it’s often among the first things I work on with my clients.

A food sensitivity is a type III or type IV reaction that involves IgA, IgG, or IgM antibodies and can show up anywhere from hours up to 3 days of consuming a food you’re sensitive to. This makes these food sensitivities especially hard to pinpoint! Often, these reactions are less obvious, and can include any of the following:

  • Abdominal pain or bloating
  • Diarrhea or constipation
  • Acid reflux
  • Headaches + migraines
  • Joint pain
  • Fatigue
  • Brain fog
  • Skin problems like acne, dermatitis, or eczema

Now, I’m often asked the best way to identify food sensitivities. You can do it one of two ways. 

Elimination Diet

First, you can do an elimination diet, where you eliminate all commonly inflammatory foods for a period of time. Once you’re feeling good, you can add each food group back methodically, one by one. You then wait for 3 days and note any reactions. Feeling great? Sweet! That food can be reintroduced to your diet. Note any symptoms? Keep that food out for now. Greater gut healing needs to be done.

Food Sensitivity Test

There are a lot of these on the market! The most common one you’ll see is the IgG test, which measures the IgG antibodies produced in response to different foods. The issue with this is that we produce IgG antibodies as a normal response to foods we eating commonly, but we don’t necessarily have an inflammatory reaction to those foods. So we get a lot of false positives. We also aren’t able to see any reactions when other antibodies are involved, so we get a lot of false negatives; food sensitivities that the test just couldn’t pick up.

In my practice, I use a test called the Mediator Release Test (the MRT), where it looks at the mediators being released by the antibodies. Mediators are the chemicals antibodies release to ward off the “invaders” and they are what give us reactions. This skips over whether the food sensitivity is creating an IgG, IgA or IgM-mediated response, and looks directly at whether we are having an inflammatory reaction from the food (are these antibodies releasing mediators?). Now, no test is perfect, and this, too, can have false positives and negatives, but it’s far fewer than IgG tests. The great thing about the MRT test is that it gives you a great starting point that is bioindividual to your body.

With either of these methods it’s important to work on healing the gut in the process. We develop food sensitivities when we have “leaky gut” (which you can read more about here), and repairing your leaky gut is the only way to truly reverse your body’s inflammatory response to these foods. But with a methodical approach and a specialized gut protocol, you can do just that! Because of this, we can frequently add foods that previously bothered us back into our diets once we’ve done the proper healing.

Gluten Sensitivity

Gluten Sensitivites and Celiac Disease

Many people cannot eat gluten, and for various reasons. Celiac disease is an autoimmune condition where the immune system attacks the lining (micro-villi) of the small intestine when gluten is consumed. This leads to symptoms like cramping, diarrhea, bloating, and over time, nutrient deficiencies. The only way to reverse this is to quit gluten all-together. To truly diagnose celiac disease, blood-work and an upper endoscopy are typically performed.

There are, however, many people who have non-celiac gluten sensitivity. If you’re one of them, this means that you’re having another type of response in your body. You may be releasing more zonulin, a protein that modulates the tight junctions in your intestines, than most people in response to consuming gluten. This leads to leaky gut and increased inflammation. You may be sensitive to the harsh pesticides used to spray all non-organic wheat, or the new hybridized wheat form that was created in the last century. One of the gut health tests I do for clients, the GI-MAP, has a marker for anti-gliadin IgA antibodies. Gliadin is a protein that contained in gluten, and if you have a high number of these anti-gliadin antibodies, gluten is likely a culprit in your leaky gut and inflammation.

Gluten is an inflammatory food, no matter who you are, so in my practice, I always suggest eliminating it for a period of time and testing it, and then eating it less frequently even if you’re asymptomatic. There are many, many better sources of carbohydrate – and yes, some are grains – to consume for health.

Food Intolerances

Food Intolerances

Food intolerances are different from both allergies and sensitivities because they don’t involve antibodies at all, but exist because our body isn’t able to properly digest that food. The one most of us are familiar with is lactose intolerance, which means that we don’t have enough of the enzyme lactase to properly digest the sugar lactose that’s contained in milk. Fun fact: raw milk actually contains lactase to help our bodies break down the mlik, but when we pasteurize dairy, it kills that enzyme! It’s also why those with lactose intolerance can eat aged cheese, but not fresh milk; aged cheese has very little, if any, lactose.

Another intolerance many of my clients have is one to FODMAPS. FODMAPS are a type of carbohydrate that are frequently over-fermented in the gut where there is gut dysbiosis or bacterial overgrowth in the wrong place, resulting in symptoms like bloating, gas, diarrhea, aor constipation. High FODMAP foods, such as onions, garlic and cruciferous vegetables, are something we can avoid short-term for symptom relief, but should not be removed from the diet for extended periods of time, as they’re really great for feeding good gut bacteria too! It’s best to work with a practitioner to get your gut into balance so that you can tolerate these foods again without the bloat!

Interested in discovering your food sensitivities and repairing your leaky gut? Schedule a discovery call with me here to see how we might be able to work together.

Ready to tackle it on your own? My completely free 7-day Leaky Gut Meal Plan can help with one less thing to figure out! Download it by clicking on the button below.