Food Allergy vs. Food Intolerance: What's the Difference?

by Elliot Reimers, M.S.(C), CISSN, CNC | Reviewed by Advisory Board

Food allergy vs. food intolerance

Food Intolerances and Food Allergies: Myths vs. Facts

Gluten-free, dairy-free, peanut-free, and soy-free seem to be an emphasis of food products as of late. Hypoallergenic claims catch the eyes of many consumers, even those who don't have any known food allergy. 

Many people mistake food intolerances as being synonymous with food allergies. Both food allergies and food intolerances share a handful of similarities, but there are finer points that need to be clarified about these terms and their prevalence. 

Read on as this article takes a deeper look at the difference between food allergies and food intolerances, as well as how to address these issues appropriately.

Food Allergy vs. Food Intolerance: What's the Difference?

It's not uncommon for people to the use the terms food allergy and food intolerance interchangeably, despite them being far from the same thing. A food allergy is a much more serious concern than being intolerant or insensitive to a food. Food allergies are typically caused by genetics/heredity and are rarer than food intolerances (more on this in just a bit).

For example, gluten - a family of proteins commonly found in wheat-based food - is hard for the body to break down since humans lack the necessary enzymes to fully assimilate it. However, people with celiac disease - a serious autoimmune condition - or a wheat allergy will experience harsh, if not fatal, reactions to gluten. In these individuals, the small undigested fragments of gluten can rapidly damage the lining of the small intestine, leading to gastrointestinal complications. Hence, acute consumption of gluten/wheat could lead them on a trip to the hospital. 

A food intolerance, such as lactose intolerance, is usually nowhere near as noxious as a food allergy. Food intolerance arises when the body doesn't produce enough of the digestive enzyme(s) necessary to completely break down a certain nutrient in food. 

A food allergy is when the body triggers an autoimmune response (i.e. the immune system attacks healthy cells) after consuming a food with the offending allergen (e.g. gluten, soy, and profillin). As such, food allergies must be treated with extreme caution since they can be fatal in some cases. 

What Are the Most Common Food Allergies?

Seafood allergy is currently the most common of all food allergies, followed closely by peanut, soy, milk (dairy), tree nuts, egg, and wheat. The obvious workaround for a food allergy is to simply avoid all foods that contain the offending allergen. Granted, this can make eating out quite stressful for some people. 

The major issue with dining out when you have a food allergy is cross contamination. Restaurants may not always do the best job of using cleaning surfaces or cookware between prep, leading to trace amounts of allergens sneaking their way into the final dish. The same can happen at home when cooking meals for multiple people, some of whom have a food allergy and some whom don't. 

Fortunately, most restaurants have taken proactive measures to ensure that hypoallergenic dishes are available for patrons with food allergies. 

Symptoms of Food Intolerances and Food Allergies

Symptoms of an allergic reaction to food may include:

  • Rapid swelling of the face, lips, tongue or other parts of the body
  • Dizziness or fainting
  • Itchy skin, hives, or eczema
  • Tingling sensation in the mouth
  • Difficulty swallowing and breathing
  • Sinus congestion 

Symptoms of food intolerances are comparatively mild. They generally include transient abdominal discomfort, bloating, flatulence, and diarrhea. Nevertheless, a food intolerance can be quite unpleasant if left uncontrolled.

The good news is that a food intolerance is more tractable than a food allergy. For example, certain probiotic strains are capable of producing lactase, the enzyme responsible for digesting lactose. The majority of humans lose their inntate capacity to digest lactose as part of the aging process, so lactose intolerance is very common [1]. But that doesn't mean you need to eliminate dairy altogether. 

In fact, research has shown that taking a probiotic with lactase-producing bacteria can mitigate the symptoms of lactose intolerance after consuming dairy [2]. It's also suggested that supplementing with digestive enzymes can alleviate symptoms of food intolerance by helping the body fully assimilate tough-to-digest nutrients like gluten, cellulose, and phytates [3]. 

Prevalence of Food Allergy vs. Food Intolerance

Researchers estimate that 1 in every 10 people in the United States has a food allergy [4]. Curiously, the number of people that think they have a food allergy is much higher. There seems to be a phenomenon of hypochondria when it comes to food allergies and food intolerances.

Given the recent boom in gluten-free food products, you might presume Celiac disease is very common. Yet, statistics suggest otherwise -- that just one in every 143 people have Celiac disease [5]. Moreover, research indicates that the prevalence of non-celiac gluten insensitivity is limited to roughly one out of every 200 people in the U.S. [6]

Determining the true prevalence of food intolerances is a bit trickier, since they often go undiagnosed and the symptoms are largely subjective (e.g. "my stomach 'feels' heavy after eating dairy"). Case in point, passing gas, whether farting or burping, after a meal is not necessarily an indicator of a food intolerance. It's actually a completely normal and healthy ramification of the digestive process in most cases [7].  

How to Determine if You Have a Food Allergy or Food Intolerance

The best thing you can do for identifying a food allergy is have a doctor or nutritionist order appropriate blood work and have genetic testing done. Another effective method is an oral food allergy challenge, whereby you eat various foods that may or may not give rise to an allergic reaction (this is usually done under the supervision of a doctor). 

For testing food intolerances, an elimination diet is a practical diagnostic measure. An elimination diet is done by systematically removing certain foods from your diet (such as dairy if you fear lactose is an issue) and assessing how you respond over the course of a few months. It’s important to consider that an elimination diet should last at least one to two months as symptoms can take some time to fade. 

For example, if you remove all dairy from your diet for two months and find that your intolerance symptoms (e.g. bloating, flatulence, and diarrhea) disappear, then chances are you’re indeed lactose intolerant. 

Interestingly, data doesn't seem to support the rising emphasis on wheat/gluten-free foods that we've witnessed in recent years. This is not to say that some people should avoid gluten and wheat-based foods, because it is a legitimate concern for a small percentage of the population. However, it is a statistical improbability to have a food allergy of any kind, and the three most common food allergens are seafood, peanuts, and cow's milk.  

Hopefully this article cleared up any ambiguity between food allergies and food intolerances. When in doubt, try an elimination diet to be sure you’re eating the foods that your body can properly digest. 

Elliot Reimers, M.S.(C), CISSN, CNC
Elliot Reimers, M.S.(C), CISSN, CNC


Elliot holds a B.S. in Biological Sciences from the University of Minnesota, as well as being a Certified Sports Nutritionist (CISSN) and Certified Nutrition Coach (CNC). He is currently pursuing a Master's of Science in Molecular Pharmacology and Toxicology at Michigan State University. Elliot began freelance writing circa 2012 and has since written 100s of articles and several eBooks pertaining to nutritional science, dietary supplements, exercise physiology, and health/wellness. Being a “science whiz,” he has a passion for helping people understand how nutrients (and other chemicals) and exercise work on a cellular and molecular level so they can make smarter choices about what they put in, and do with, their bodies. When Elliot is not busy writing or studying, you can find him pumping iron, hiking the mountains of beautiful Colorado, or perusing nutraceutical research.

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