Have you ever wondered what is the difference between a food allergy, sensitivity, and intolerance?  Have you contemplated whether a specific food or food family was the culprit for your low energy or fatigue, poor, sleep,  deadly gas, constipation, skin/hair/nail issues, etc.?

Since approximately 70-80% of our immune system can be found in the gut, there is a pretty good chance that a food allergy, sensitivity or intolerance is, in fact, the reason you are not feeling you’re very best.[1] The tricky part about this whole concept is that most healthcare professionals are not educated on the topic of adverse food reactions and even those who are, do not completely understand the difference between a food allergy, food intolerance, and food sensitivity. I hope this article will shine a bit of light on the subject.

Let’s start with food allergies since this is a term most people recognize.

Food Allergy

A true food allergy involves the immune system. This reaction is commonly referred to as a Type I Immunoglobulin E (IgE) Hypersensitivity response. An allergic reaction occurs when your body mistakes a “safe” protein for an invader and begins to attack the food item that contains the protein.3 Your body then releases an organic nitrogenous compound known as histamine as a way to “fight” the protein. When histamine is released, your body may react by experiencing hives, coughing, vomiting or wheezing. Although most food allergies appear during early childhood, it is very much possible for an adult to suddenly experience this reaction.

It is important to note that a food allergy will always occur shortly after consumption. Typically the symptom(s) can be detected within minutes but for some individuals, it may take a few hours before the individual feels symptomatic. The reaction is typically severe in nature.

The most common symptoms of a food allergy include but are not limited to: wheezing, coughing, vomiting, difficulty breathing or a closed airway/tightening of the throat, hives, severe abdominal pain, rash, itchy or swollen tongue.

Surprisingly, just 8 foods cause a majority of food allergies. The most common sources of food allergies include but are not limited to: milk, wheat, egg, corn, soy, fish, shellfish, tree nuts (particularly peanuts).[3]

Food Sensitivity

The term food sensitivity is often used interchangeably with food allergy even though they are completely different immune reactions! A food sensitivity is often referred to as a delayed hypersensitivity response, meaning that the individual may not present with symptoms until several hours or even several days later.  A food sensitivity is also very dose-dependent. As you can imagine, this makes food sensitivity detection a bit more difficult than an allergy

Do you have acid reflux or frequent GI upset after eating? This may be due to a food sensitivity or intolerance.

While a food sensitivity also involves the immune system, the method of action is separate from a food allergy. A food sensitivity includes every immune response other than a Type I Hypersensitivity response. The most common sensitivity reaction to foods includes Type 3 Immune Complex Mediated Hypersensitivity and Type 4 Cell-Mediated Hypersensitivity.5 Food sensitivities are much more common than food allergies and they typically occur as a result of a gastrointestinal system imbalance, most commonly referred to as intestinal permeability.

Intestinal permeability occurs when the lining of the gut has been disturbed by the outside world. Processed foods, certain medications, pathogens, toxins, and stress are the biggest offenders. As we age, our immune system struggles to carry the load, thus leading to intestinal permeability. Food particles that should be contained in the intestines suddenly start to slip through the lining and then magically appear in your bloodstream. Your body realizes that the food should not be in your bloodstream and as a result, it begins to attack the particles. My athletes often say to me, “But I have been eating ___ my entire life!!! How could I possibly be sensitive to that food all of a sudden??” The answer is that your gastrointestinal system is likely out of balance because of what it has been exposed to over the years and now your body is fighting back.

Conditions commonly exacerbated by food sensitivities include but are not limited to: Fibromyalgia, IBS, migraine, eczema, Autism Spectrum Disorders, Arthritis, Chronic Fatigue, Urticaria.[1]

The most common symptoms of a food sensitivity include but are not limited to: headaches, nasal drip or congestion, excess mucus production, fatigue, irritable bowel, acne, muscle or joint pain, nausea, reflux, dark circles under the eyes, bladder control issues, bloating, mood swings, dizziness, difficulty sleeping, anxiety, depression, dry skin and excessive sweating. Now if you experience one of these reactions from time to time, it’s probably nothing to worry about but if this is something you experience on a routine basis, you may want to strongly consider keeping a close eye on your diet. It’s amazing what you might be able to detect!

The most common food sensitives are corn, dairy, wheat, egg, and soy, however, there is no limit as to what an individual can react to. It is entirely possible to have this type of reaction to broccoli, blueberries, legumes, grains, cilantro and beyond!

Food Intolerance

Last but not least, a food intolerance is the least severe of the three possible reactions. Food intolerance does not involve the immune system and typically stems from a reaction to a component of a specific food vs. the food item itself. For example, an individual may react to lactose, the sugar in milk or lectins which are indigestible proteins found in certain foods such as legumes and grains. A food intolerance occurs when our body lacks a certain nutrient or enzyme needed to break down that particular component of the food.[1,5]

The symptom(s) of food intolerance are typically immediate and occur more quickly than a food sensitivity, but are not as severe as an allergic reaction.

The most common symptoms a food intolerance include but are not limited to: flushing, diarrhea, general discomfort, and cold or flu-like symptoms.

The most common foods/food components are known to trigger a food intolerance include but are not limited to: histamines, lactose, lectins, preservatives, alcohol, artificial fillers, flavorings, and colors, acidic foods, citrus fruits, and sulfites.

Now that you know the difference between a food allergy, sensitivity, and intolerance you can take better control of your health. If you suspect an allergy, schedule an appointment with your local allergist. If you suspect a food intolerance or sensitivity, start to keep a food journal and track all symptoms. MySymptoms app is one of the most convenient trackers when it comes to food reactions.  After 3-4 weeks of tracking, there is a good chance you will be able to detect a pattern. If it’s still confusing, schedule an appointment with a dietitian in your area and share your log during your visit.

Just remember, the sooner you pinpoint your reactive food(s) the sooner you will be able to calm the inflammation in your body. The better you are able to calm the flames of inflammation, the better you will recover post-workout, heal when injured, and prevent chronic illness long term!

What has been your greatest challenge or issue with a food allergy, sensitivity, and intolerance?  Leave some of your thoughts in the comments below or feel free to contact us directly if you’re interested in a virtual consult!


  1. Taylor, S., S. Hefle. Food Allergies and Other Food Sensitivities, Food Technology., September 2001, Volume 55., NO 9
  2. Farré R, Tack J. Food and symptom generation in functional gastrointestinal disorders: physiological aspects. Am J Gastroenterol2013; 108: 698–706.
  3. O MH, Wong WH, Chang C. Clinical spectrum of food allergies: acomprehensive review. Clin Rev Allergy Immunol 2014;46: 225–240.
  4. Bischo  S, Crowe SE. Gastrointestinal food allergy: new insights into pathophysiology and clinical perspectives. Gastroenterology 2005; 128:1089–1113. doi: 10.1053/j.gastro.2004.08.015
  5. Francesca Pasqui, Carolina Poli, Antonio Colecchia, Giovanni Marasco, Davide Festi, Adverse Food Reaction and Functional Gastrointestinal Disorders: Role of the Dietetic Approach,  http://www.jgld.ro/wp/archive/y2015/n3/a9DOI: http://dx.doi.org/10.15403/jgld.2014.1121.243.paq