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Food allergies versus food intolerances: What is the difference?

Updated: Jan 8, 2022

These two conditions have a common misconception of being the same, caused by the misinformation of nutrition and health conditions found on the internet. Often a food intolerance might be mistaken for a food allergy or vice versa. However, a food allergy can be much more severe and even deadly compared to food intolerances.

Before I went to college at Benedictine University to study nutrition, I was one of those individuals who thought that food intolerances were in the same category as food allergies. I remember talking about this with a friend eating dinner one night who mentioned that she thought she was lactose intolerant; I replied, "does that mean you are allergic to cheese?" She explained that often after eating cheese, her stomach would hurt, and she would need to use the bathroom almost immediately. Neither of us knew what it meant to be lactose intolerant or even have a milk allergy; however, I wanted to learn more about what my friend was experiencing after she ate cheese.

Fast forward to studying nutrition; I discovered that food intolerances and food allergies are pretty different, but people can experience overlapping symptoms. A simple explanation of food intolerance is that it does not involve the immune system but affects the gastrointestinal system. Food intolerance is when someone's body cannot process a portion of food during the digestion or absorption processes caused by various things. While a food allergy is an immune response to a food, the body sees this food as an invader causing a reaction that can range from mild to severe symptoms.

The common symptoms that may occur after eating a food that an individual is intolerant to include but are not limited to are diarrhea, gas, bloating, abdominal pain, and occasionally nausea. One reason that allergic reactions vary from mild to severe is multiple body systems can be involved. The typical mild symptoms, but are limited to are a runny nose, itchy and watery eyes, even asthma. Not only can one of the body's systems be involved, but all of the body's systems can be involved in a food allergy reaction called an anaphylaxis reaction. A few of the anaphylaxis symptoms are burning and itching of the mouth and throat, hives, nausea, and vomiting. In a severe anaphylaxis reaction, these symptoms are followed immediately after eating the food, then, loss of consciousness following death caused by suffocation due to the throat closing from severe swelling.

Both conditions have varying symptoms, sometimes overlapping symptoms such as nausea and vomiting. These similar symptoms can make it a challenge to determine if a person has an intolerance to a food or an allergy to a food. Similar symptoms are why it is essential to make an appointment with an allergist to receive specific tests to determine if it is a food allergy or food intolerance.

What furthers the confusion between food allergies and food intolerances is that either condition can cause a reaction from the same food. For example, lactose intolerance is a condition dealing with our gut's inability to break down lactose (sugar in milk). Then there is a milk allergy, a response from our immune system after drinking milk. Even though the symptoms are much different and how the body responds to the food, these reactions can both happen after drinking milk.

The symptoms of food allergy reactions are much more severe than symptoms of a food intolerance reaction. However, both of these conditions can impact an individual's daily life with how they make their food choices or eat in social gatherings, whether at family parties or going out for dinner with friends. Fortunately, registered dietitians like me can help individuals with either condition find the foods that are safe for them to eat with the proper nutrition that will help them flourish.

#foodallergies #foodintolerances #foodsensitivities


Audrey Butler, RDN, LDN is a Dietitian in Chicago who helps individuals implement a nutritionally-balanced diet using a plant-forward approach to feel healthy and energized. As a vegetarian nutritionist, she knows first-hand what the journey is like to implement a nutritionally-balanced diet, vegan diet, vegetarian diet, and plant-based diet located in Chicago.

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