Published 11th January 2022

What’s the difference between food sensitivity, intolerance, and allergy?

Food sensitivity, food allergy, and food intolerance are all terms used to describe conditions that cause unpleasant symptoms after you eat certain foods. 

Of the three, food allergies are the best defined. If you have a food allergy, your immune system mistakes harmless food proteins as dangerous. Allergic reactions can range from rashes or itchiness to anaphylaxis, which can be fatal if not treated.

Food sensitivities, or non-classical food allergies, are more common than classical food allergies. 

Scientists don’t understand as much about food sensitivities as they do about food allergies, but they are also the result of an immune reaction to certain foods. Food sensitivities can cause a range of symptoms, but they’re not life-threatening like classical food allergies. 

Unlike food allergies or food sensitivities, food intolerances don’t involve a reaction from your immune system. They are digestive problems caused by an inability to break down substances in certain foods, like lactose intolerance after eating dairy products.

There’s some evidence that food allergies and food sensitivities may be linked to imbalances in the makeup of your gut microbiome, which is the name for the trillions of bacteria and other microbes that live in your gut. 

At ZOE, we don’t test for food allergies, sensitivities, or intolerances. If you are concerned about a reaction to food, you should consult a healthcare professional.

Read on to learn more about the differences between food allergies, food sensitivities, and food intolerances, as well as what you can do to manage symptoms. 

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Food allergies

Food allergies happen when your immune system mistakes harmless food proteins for dangerous invaders and reacts to them. 

Scientists are not completely clear on why some people develop food allergies and others don’t.

Allergies can affect different parts of the body and can cause a range of symptoms, including:

  • wheezing or difficulty breathing 

  • feeling dizzy or lightheaded

  • feeling sick or vomiting

  • hives

  • itchy red rashes

  • swollen lips or face

  • swollen throat and difficulty swallowing

  • stomach pain or diarrhea

  • sneezing

  • itchy eyes

  • anaphylaxis

There is no cure for food allergies, but there are treatments to help you cope with the symptoms. Avoiding eating food that contains the protein you are allergic to is the best way to prevent allergic reactions.

A severe food allergy can lead to anaphylaxis, sometimes known as anaphylactic shock, which can be life-threatening.  

If it’s not treated, anaphylaxis can cause damage to your organs and lead to a heart attack. 

If you have a severe food allergy, your doctor may give you an epinephrine pen to carry with you. 

These EpiPens deliver a quick dose of epinephrine, also known as adrenaline, in an emergency situation. This counteracts the allergic reaction by increasing your blood pressure and your heart rate.

Food sensitivities

Scientists don’t know as much about food sensitivities as they do about classical food allergies. Food sensitivities are sometimes called non-classical food allergies, and they are also the result of a reaction from the immune system. 

While these types of reactions don’t lead to anaphylaxis, they can be the cause of significant discomfort. 

Symptoms of food sensitivities include:

  • stomach pain

  • diarrhea

  • vomiting

  • joint pain

  • rashes

  • headaches

  • hives

  • fatigue 

  • brain fog

  • blood in the stool

If you have ongoing food sensitivities, the symptoms can lead to longer-term issues, including damage to the lining of your gut. Small molecules can then slip through the lining and increase the risk of more reactions and new sensitivities. 

This can happen with classical food allergies as well as food sensitivities.  

If you have a suspected food sensitivity, your doctor or dietitian may recommend that you remove certain foods from your diet for 4 to 6 weeks while they monitor your symptoms to see if they improve. 

At the end of the elimination period, you’ll slowly reintroduce each eliminated food to your diet, one at a time, to see if your symptoms come back or get worse. 

Food sensitivities can improve over time. Diet, lifestyle changes like exercise and reducing stress, and medication can all potentially play a role in managing the symptoms. 

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Food intolerances

Unlike food sensitivities or food allergies, food intolerances don’t involve your immune system. They are digestive problems that cause symptoms in your gut.

Food intolerances may be due to the lack of a specific enzyme needed to digest certain foods, such as with lactose intolerance.

People with lactose intolerance don’t have enough of the enzyme lactase in their guts, so they can’t properly digest the lactose in milk and dairy products. This can cause bloating, gas, and changes to bowel movements.

Food intolerances like lactose intolerance can be genetic and run in your family. They may also be related to other conditions, such as irritable bowel syndrome (IBS) or gastrointestinal (GI) diseases. Food intolerances have even been linked to taking long courses of antibiotics. 

The symptoms of food intolerances are usually limited to digestive issues. They can range from mild to debilitating and may include: 

  • cramps

  • constipation

  • bloating

  • diarrhea

  • gas

For some people, food intolerances can cause other issues, including headaches, skin reactions, or shortness of breath.

For people with IBS, digestive reactions to high-FODMAP foods can be one cause of food intolerance symptoms. FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols, which are types of sugar found in specific foods. 

IBS is complex, but a low-FODMAP diet has been shown to improve symptoms. If you have symptoms of food intolerance, your doctor may recommend reducing specific foods or removing them from your diet. 

Food intolerances don’t always have a single, easily identifiable cause, however. If you’re worried about a food reaction you’re experiencing, it’s important to talk to a trusted healthcare professional before you restrict what you eat. 

Gut health

There’s some evidence that food allergies and food sensitivities may be linked to imbalances in the makeup of your gut microbiome, which is the name for the trillions of bacteria and other microbes that live in your gut. 

There's even evidence that microbiome imbalances may precede food allergies. Some studies have found differences in the composition of the gut microbiome between people with food allergies and those without them. 

At ZOE, we don’t test for food allergies, sensitivities, or intolerances, but we are experts in metabolic health and the gut microbiome. We run the largest study of gut bacteria in the world, with over 10,000 contributors to date. 

The ZOE at-home test analyzes your unique gut microbiome and tells you what your individual “gut booster” foods are, which support the good bacteria in your gut. 

Find out more about what the ZOE program can do for you here.

Summary

Food allergies, sensitivities, and intolerances can share some symptoms, but there are important differences between them. 

Food allergies are an unwanted response by your immune system. Symptoms can range from skin rashes to anaphylaxis, which can be life-threatening. 

Food sensitivity symptoms are also caused by your immune system. They can include vomiting, diarrhea, headaches, skin rashes, and joint pain, but not anaphylaxis. 

The symptoms of food intolerances are generally only digestive. They can happen when you don’t have enough of the enzymes that help break down certain substances in food.

If you have a food allergy, your doctor may give you an EpiPen in case of a severe reaction. If a healthcare professional suspects that you have a food sensitivity or food intolerance, they may ask you to eliminate certain foods from your diet to find out what’s causing your symptoms.

At ZOE, we don’t test for food allergies, sensitivities, or intolerances. If you think you might have any of these, you should talk to your doctor.

The ZOE at-home test analyzes your gut microbiome, as well as your blood sugar and blood fat responses to the foods that you eat. With the ZOE program, you can find out the best foods for your metabolic and gut health.  

Take a free quiz to find out what ZOE can do for you.

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