Food intolerances are often confused with food allergies, but they are actually very different.
When you have a food allergy, your immune system mistakenly identifies a substance in a food as a threat. In response, it produces antibodies that cause an allergic reaction. The reaction can range from mild to life-threatening depending on the kind of allergy you have.
When you have a food intolerance, your digestive system is unable break down a particular kind of food. Eating these foods usually causes gastrointestinal symptoms like abdominal pain, bloating, gas, and diarrhea.
You can develop food allergies and food intolerances at any time in your life or grow less tolerant of certain foods as you age.
Intolerance basics
A food intolerance can be difficult to diagnose. To find out if you have one, your doctor may recommend going on an elimination diet. To begin this type of diet, you stop eating foods known to cause food-intolerance symptoms. Then, you slowly reintroduce each food into your diet to see how your body reacts.
Food intolerances are slightly misnamed. You don’t have an intolerance to an entire food; only to some of its components. For instance, some people have an intolerance to the proteins or carbohydrates found in certain foods, such as gluten, lactose, and fructose.
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Other intolerances are caused by chemicals — including ones added to foods to preserve them or give them flavor. Such chemicals include histamines, salicylates, caffeine, sulfites, and monosodium glutamate.
Lactose intolerance
The most common food intolerance involves a sugar that’s the main carbohydrate in most dairy products.
Lactose intolerance affects at least two-thirds of the world’s adult population. If you have it, your body doesn’t make enough lactase. That’s the enzyme that enables your digestive system to break down lactose.
Lactose intolerance symptoms are the typical gastrointestinal problems caused by many food intolerances. Unlike most food intolerances, lactose can usually be diagnosed by breath and blood tests.
Treatments for lactose intolerance include taking over-the-counter lactase supplements, or eating foods (or supplements) containing lactase, probiotics, and prebiotics. If you give up dairy products entirely, you should try to eat other calcium-rich foods.
Gluten intolerance
Another very common food intolerance involves gluten, a protein found in wheat and some other grains.
Gluten intolerance affects about six percent of the U.S. population. Its exact causes aren’t known.
Gluten intolerance is different from celiac disease. That’s a disorder that causes your immune system to attack gluten in your small intestine, damaging your organ in the process.
Gluten intolerance symptoms resemble those seen in most other food intolerances, plus anemia, anxiety, constipation, joint pain, and having trouble concentrating. To diagnose gluten intolerance, your doctor may have you modify your diet and perform tests to see if you have wheat allergies or celiac disease.
There are plenty of gluten-free versions of products that would otherwise usually contain gluten. Just be sure to consult with your doctor before making a major dietary decision. A gluten-free diet may increase your risk for high blood sugar or Type 2 diabetes. It can also cause nutritional deficiencies, such as too little fiber. For these reasons, it’s extremely important to keep your health care provider in the loop.
Fructose intolerance
Fructose intolerance involves an inability to digest fructose, a sugar found in many fruits and some vegetables. It’s also found in many foods and beverages that use high-fructose corn syrup as a sweetener.
If you have hereditary fructose intolerance, you lack the enzyme that breaks down fructose and can’t digest it all. That means eating any fructose can be harmful to your health. Symptoms include bloating, gas, stomach pain, and diarrhea.
A test can help determine whether you have dietary fructose intolerance, but not conclusively. As a result, elimination diets are often used to diagnose it.
Cutting out fructose entirely can be difficult, as it involves not eating a lot of foods. Some people with dietary fructose intolerance can eat fruits that are relatively low in fructose. Those include avocados, bananas, cranberries, cantaloupe, lemons, limes, oranges, pineapples, and strawberries.
Histamine intolerance
Histamine is a chemical that performs multiple functions in your body, including triggering your immune system to react to an allergy. The chemical is present in many foods. If you eat those foods and don’t have the enzymes needed to break down histamine, it may get into your blood and cause your immune system to react.
In addition to normal food intolerance symptoms, histamine intolerance’s symptoms include a runny or stuffy nose, itchy eyes, dizziness, and heart palpitations.
Doctors often diagnose histamine intolerance by eliminating other conditions that could be causing its symptoms. If your doctor suspects you have it, they may ask you to keep a diary of what you eat. They also may give you a blood test to determine your enzyme activity levels.
So many foods have histamines, trigger their release, or interfere with the enzymes that digest them that avoiding them all isn’t possible. You can go on a diet that is low in histamines, although your doctor will need to monitor your health if you do.
The bottom line
Food intolerances are different from food allergies. They can be hard to diagnose and tough to deal with at times, but, fortunately, you can manage their symptoms through dietary changes made in consultation with your doctor.