How to Tell if You Really Have a Food Intolerance

Chances are you know someone who’s on a special diet these days, and for good reason. According to one German study, more than 20 percent of people around the globe have a food intolerance or allergy. The thing is, it’s not always so easy to figure out if you have a food intolerance because the symptoms can all be signs of other conditions.

If you regularly experience bloating, gassiness, or indigestion and are wondering whether you have a food intolerance, here’s what you can do to figure out what’s going on. 

food intolerance

What is a food intolerance?

According to the American Academy of Allergy, Asthma, and Immunology, a food intolerance happens when you have trouble digesting a particular type of food.

“Lactose intolerance is the most common food intolerance I’ve come across,” says Aja Gyimah, RD, nutrition expert with kuudose. “Other common intolerances include monosodium glutamate (MSG), alcohol. and caffeine.”

Gluten intolerance is also a common food intolerance, says Carrie Gabriel, RD, founder of Steps 2 Nutrition. With a food intolerance, “you may experience bloating, stomach pain, gas and diarrhea,” says Gyimah. 

Per the Mayo Clinic, the most common causes of a food intolerance include:

  • Lack of an enzyme needed to properly digest a food. People with lactose intolerance lack enough of the enzyme lactase to digest the sugar in milk. 
  • Irritable bowel syndrome (IBS). Those with IBS, a chronic condition, are often sensitive to foods. Per the IBS Network, wheat, milk, chocolate, spicy food, onions, and coffee are all triggers for people with IBS.
  • Celiac disease. This is an autoimmune disease caused by eating gluten, a protein found in wheat and other grains. For those with celiac disease, gluten not only causes symptoms associated with food intolerance, but it also causes intestinal damage. 
  • Stress. A study in the American Journal of Pathology shows that psychological stress can trigger a reaction in your gut and worsen intestinal disorders. 
  • Sensitivity to food additives. Per research in BMC Medicine, the most common food additives you can become intolerant to are sulfite, sodium benzoate, and food colorings. The Mayo Clinic notes that these additives can trigger asthma in people who are sensitive to it. 

Food intolerance vs. food allergy

A lot of people use the terms intolerance and allergy interchangeably, but they are actually two different things. Unlike a food intolerance, a food allergy involves your immune system rather than your digestive system. It causes your immune system to overreact to a protein found in a specific food. 

The most common food allergies are to milk, eggs, fish, shellfish, peanuts, soy, tree nuts and wheat. Symptoms can be similar to a food intolerance (think: abdominal pain and diarrhea), but you may also experience the typical signs of allergic reaction, like hives or itchy eyes. And unlike a food intolerance, a food allergy can be life-threatening, so it’s important to be super-careful to avoid that food going forward. 

How to tell if you have a food intolerance (and how to deal with one if you do) 

If you suspect you have a food allergy, get tested by your doctor ASAP since it can be life-threatening. You can get a skin test or blood test to confirm a food allergy. 

If you don’t have a food allergy but still think you might have a food intolerance, start by tracking everything you eat.

“I definitely recommend monitoring your symptoms and then tracing those back to what you’re eating,” says Gyimah. “You can keep a food journal if you’d like, or you can also use your phone to take pictures of your meals if you have trouble remembering what you’ve eaten that day.” 

It’s also important to be mindful while you eat, and keep stress to a minimum (since that can trigger a reaction).

“Even if you do have a list, there might be something you’re intolerant to, or have a sensitivity to, that you’re just not thinking of,” says Lauren O’Connor, RD, author of Healthy Alkaline Diet Guide, who specializes in treating patients with acid reflux. “Instead of stressing about it, have that awareness, eat slowly and mindfully, and choose your meals wisely.” 

Once you’ve IDed the foods you think are causing your tummy troubles, it’s time to try an elimination diet.

“If you’re regularly experiencing symptoms like bloating, stomach pain, gas, and diarrhea and suspect that you have a food intolerance, remove the food from your diet for a while and then reintroduce it,” suggests Gyimah. “See if the symptoms disappear while the food is removed and see if the symptoms return when you reintroduce it.” (Some experts recommend cutting alcohol and coffee out too while you’re on an elimination diet.)

You’ll want to stay on the elimination diet for at least two weeks, says Gabriel, then reintroduce foods in small amounts to see if you can tolerate a little bit of that food. 

Be careful about cutting entire food groups out of your diet to ensure you’re not missing out on key nutrients. Say you find out you’re lactose intolerant: That doesn’t mean you have to give up all dairy products, which are rich in calcium.

“Many people who have an intolerance to lactose can tolerate certain yogurts and cheeses because of the low lactose content,” says Gyimah. “You can also try lactose-free milk.” 

Living with a food intolerance

To make living with a food intolerance easier, it’s good to have a repertoire of go-to easy recipes and grocery items, says Gabriel. She points out that there are plenty of food sensitivity bloggers and Instagram accounts you can follow for ideas. If you’re gluten intolerant, for example, build your grocery list around a few favorite proteins (like chicken, salmon, and ground turkey), vegetables (like broccoli, Brussels sprouts, and spinach), and a starch (like sweet potatoes) that you can mix and match. 

Elimination diets and food intolerances can be tricky to navigate on your own, so don’t hesitate to visit a dietitian to help guide you during this process.

“If you’re worried that you’re not getting the right nutrients, an RD can create a personalized plan that will ensure you’re meeting all of your needs,” says Gyimah. “An RD can also help you with your elimination diet and help you adjust to your new diet that does not include the suspected food or foods.” 

Want more from aSweatLife? Get us in your inbox!

Eat Hacks & Tips

About Christina Heiser

Christina Heiser is a freelance writer who covers beauty, health, nutrition, and fitness. As a lifelong New Yorker, she loves exploring her city by foot, cheering on her favorite local sports teams (Let's go, Mets!), and checking out all of the trendy boutique fitness studios. Christina graduated from St. John's University in 2010 with a degree in English and a passion for reporting. After graduating, Christina went on to work for and, covering everything from beauty to fitness to celebrity news. Now, she contributes to a variety of beauty- and wellness-focused websites including aSweatLife, NBC News Better, Total Beauty, and What's Good by Vitamin Shoppe.