Food Allergy Vs. Sensitivity: 5 Key Differences

The terms “food allergy” and “food intolerance/sensitivity” often get used interchangeably. However, they’re different things with different causes. The Rogue Scientist explains.

I will devote many articles to the topic of food sensitivities and allergies.

Why? Two reasons.

First, I have food sensitivities, so they interest me because I have a dog in this race, so to speak. (By the way, food sensitivity and intolerance mean the same thing, so for simplicity I will stick to the former for the rest of this article).

Second, and this is just as important, the scientific and medical communities know so little about food allergies and sensitivities. Especially food sensitivities.

Why do people develop allergies and/or sensitivities to foods?

Why do people seem to have more food allergies/sensitivities than ever before?

What do you do about them? Can you cure them?

All great questions. I want to tackle those questions over time, but to do so I need to clarify one important point: 

Food allergy differs from food sensitivity or intolerance. They are not the same thing.

This is important. If you want to understand something and eventually treat it, you need to know exactly what you’re dealing with. 

This article explains the 5 key differences between food allergy and food sensitivity.

Key Difference #1: Food Allergies Involve the Immune System, Food Sensitivities Do Not

An allergy will trigger the immune system. When a foreign invader enters your body, the immune system develops antibodies to fight the invader. This happens when you catch a cold or flu, get an infection, or when you receive a vaccine.

However, the immune system can also target certain foods as “invaders” and launch an attack if that food gets consumed. This immune response causes your symptoms.

Typically, upon consuming a food you have an allergy to, the body will produce immunoglobulin E (IgE) antibodies and mast cells will release histamines. Non-IgE food allergies exist too; these do not appear to cause anaphylaxis or other life-threatening reactions.

Food sensitivities, on the other hand, don’t trigger an immune response. Food sensitivity reactions stem from other causes, which I discuss later in this article.

Key Difference #2: Food Allergies Have Different Symptoms Than Food Sensitivities

Although allergies and sensitivities can generate some similar symptoms (further adding to the confusion between the two things), food allergies often cause certain kinds of symptoms, which can become severe.  

For example, skin reactions such as hives, itching, and swelling (especially face swelling) tend to indicate a food allergy. Ditto with oral symptoms such as tingling/itching of the mouth and swelling of the lips, tongue, or throat, and respiratory symptoms such as wheezing, congestion, or trouble breathing.

In severe cases, a food allergy can lead to anaphylaxis, which can cause tightening of airways, swelling in throat, dizziness, loss of consciousness, and even death if untreated.

Side note: Mild oral symptoms only after eating raw fruit or veggies may indicate oral allergy syndrome, which is somewhat common, especially if you have hay fever or other environmental allergies.

Food sensitivities, on the other hand, tend to cause digestive symptoms (bloating, gas, diarrhea, nausea), headaches, brain fog, fatigue, flushing, even mental symptoms such as depression or anxiety. Food allergies can also cause digestive symptoms, but like other food allergy symptoms they tend to be more severe, such as abdominal pain and vomiting.

Finally, when it comes to symptoms, a food allergy reaction will typically occur very quickly after ingesting a problem food, while reactions in those with food sensitivities can set in hours or even a day or two later.

Key Difference #3: Allergies Often Involve Different Foods Than Sensitivities

According to Healthline, 90% of allergic reactions result from eight foods: milk, eggs, fish, shellfish, peanuts, tree nuts, wheat, and soybeans. Fish, shellfish, and peanuts are pretty easy to avoid, but avoiding eggs, wheat, and soy can prove really difficult because they get added to so many food products.

You can be sensitive to those eight foods, certainly. But the realm of food sensitivities includes a much wider variety of foods. It also includes a wide variety of specific compounds found in foods. For example:

  • Gluten (present in wheat-based products)
  • Dairy (but not milk or casein allergy)
  • Amines (tyramine, histamine, etc) in aged and fermented foods
  • Food additives and preservatives (glutamates, sulfites, benzoates, etc)
  • Nightshade foods (tomatoes, bell peppers, hot peppers, eggplant, potatoes)
  • Salicylates (present in many fruits and vegetables)
  • Caffeine

See this article for a more complete list.

Key Difference #4: Food Allergies Have a Different Cause Than Food Sensitivities

As mentioned above, food allergies stem from your body identifying a particular food as a pathogen. This kicks your immune system into mounting a defense, resulting in symptoms that can range from uncomfortable to dangerous.

Why does the body do this? We don’t know.

On the other hand, food sensitivity results because the body has a difficult time breaking down a particular food or substance.

Lactose and Tyramine Intolerance

A common, well-known condition, those with lactose intolerance have a hard time breaking down lactose, a type of sugar found in dairy products. This inability to digest lactose results in symptoms such as bloating, gas, and diarrhea.

In this case, the problem results from the body producing too little lactase, the enzyme that breaks down lactose. You can buy lactase tablets and consume them if you want to indulge in that bowl of chocolate chip cookie dough ice cream, which will help your body digest the lactose.

Tyramine intolerance also results from not enough enzyme (in this case, the MAO enzyme), and those who have tyramine intolerance need to avoid high-tyramine foods such as aged cheese, processed meats, and fermented foods.


Genetics play a role in food sensitivity. Some people can drink caffeine late at night and have zero problem sleeping, while others (me included) can’t imbibe more than a tiny amount of caffeine at any time of day without getting jittery and anxious.

It makes sense that, genetically, some of us can break down certain foods better than others.

Because of these causal differences, those with food allergies need to avoid the problem food, since even a tiny amount can anger the immune system. Those with food sensitivities can often get away with small amounts of the problem food; the problems come when you eat more than the body can break down in a given period of time.

Key Difference #5: Food Allergies are Less Common Than Food Sensitivities

Food allergies are pretty uncommon, affecting 5-10% of young children and only 2-5% of adults. Many kids will outgrow their food allergies. For example, like many kids, I was allergic to cow’s milk as a child, but outgrew it before I turned ten.

Food sensitivity, on the other hand, is more common than food allergy, affecting 15-20% of people in industrialized countries. Gluten intolerance in particular, or at least awareness of it, has ballooned over the last 10 or 15 years, generating an entire new grocery story category: GF or gluten free.

Now there’s a topic that needs more research.

Problem Foods: Allergy or Sensitivity?

One of the hardest things about food allergies, and especially sensitivities? Identifying them in the first place.

Nailing down what your body doesn’t handle well involves a lot of record keeping and detective work, and it’s easy to make assumptions. For example:

  • Reacting to bread, pasta, or other wheat products can result from celiac disease, non-celiac gluten sensitivity, or wheat allergy, just for starters.
  • Symptoms from consuming dairy products can result from lactose intolerance, casein allergy, or sensitivity to a host of other compounds in milk products.
  • Reacting to Asian food could result from many things. A common culprit could be glutamate sensitivity, but before you blame MSG, many Asian good ingredients such as soy sauce, fish sauce, seafood, mushrooms, and peas have more naturally occurring glutamates than other foods.
  • Wine: could be sulfites, histamines, or tyramines.
  • Beer: could be gluten, histamines, hops.

Lab testing for allergies has some value, since allergies are immune-mediated. Testing for sensitivities, on the other hand, can be expensive and inaccurate.

The gold standard for testing food sensitivity? Elimination diet. Stop eating that (and only that) food for a while (at least three weeks), then reintroduce it.

If you feel better during elimination, that tells you something. If you get a reaction upon reintroduction, that clinches it. The worse the reaction, the more sensitive you are, and the more you should avoid that food.

Stay tuned for more on this topic.

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The Rogue Scientist

Christie Hartman is a writer and scientist specializing in science-based health. A biology major as an undergrad, she completed her PhD in behavioral genetics at the University of Colorado Boulder. Before starting her writing career, she worked as a scientist and professor at CU’s School of Medicine, where she studied the genetic contributions to substance abuse and antisocial behavior.

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