Is It A Food Allergy, Food Sensitivity, Food Intolerance Or Celiac Disease?

You might know that a food allergy makes your lips swell and throat close up, but there are several ways that food can adversely affect you—and they’re becoming increasingly common. “They can be grouped into a few distinct categories: an allergy, a sensitivity, an intolerance and, in a unique category, celiac disease,” says Ryan Barish, M.D., a functional lifestyle medicine physician with Henry Ford Health.

Here, Dr. Barish explains the differences among these food issues and how to deal with them.   

Food Allergy

What it is: A food allergy occurs when your immune system elicits a response to certain foods (like nuts or shellfish, for example) and causes rashes, nasal congestion, nausea, swelling of the lips or tongue, and the most serious reaction, anaphylaxis, where the airways narrow and inhibit breathing.  

How long it takes for symptoms to appear: “It’s usually a short duration from the time someone ingests the food—it may be just minutes to hours—so it can be easier to connect the dots to determine what you’re allergic to,” says Dr. Barish.  

How to diagnose it: An allergist can give you a patch test, where they expose the food to your skin. They may also give you an oral challenge, where you ingest small, controlled doses of food. (They’ll give you medicine if you have a reaction.) A blood test is another option, which can usually be ordered through a primary care physician.   

How to treat it: Avoid the foods you’re allergic to, and in the case of accidental exposure, have an EpiPen on hand at all times. Some allergy specialists also offer treatment options that can desensitize you from certain food allergies, says Dr. Barish.

Food Sensitivity

What it is: When a certain food prompts the immune system to create internal inflammation, it can cause joint aches, chronic allergies and congestion, chronic skin rashes, bloating, constipation, diarrhea and migraine headaches. This is a food sensitivity.

How long it takes for symptoms to appear: You can have a food sensitivity for many years and not know, because symptoms don’t appear immediately. “It can take several days to weeks--it’s not always obvious to someone that they get sick from a certain food,” says Dr. Barish.

How to diagnose it: The gold standard to diagnose food sensitivities is an elimination diet, where you eliminate commonly inflammatory foods (such as gluten, dairy, soy, nuts and eggs) for three to four weeks, and then reintroduce them one a time to see if symptoms come back. "But an elimination diet isn’t always feasible for some people, so in these circumstances, a blood test can offer guidance to see what foods may be causing issues," says Dr. Barish. "It’s not a perfect test, but it can be helpful." 

How to treat it: While you should eliminate these foods from your diet in the short term, you may not have to eliminate them forever. “A food sensitivity is usually the result of an underlying digestive condition like increased intestinal permeability, or as it’s colloquially called, ‘leaky gut,’” says Dr. Barish. Leaky gut could be caused by bacterial gut imbalances, gastrointestinal diseases, stress, inflammation, poor digestion, certain medications, toxins or infections. While treating the sensitivities, you may also need an endoscopy, colonoscopy or stool test to diagnose these underlying issues.

Food Intolerance

What it is: Unlike allergies and sensitivities, a food intolerance does not involve the immune system. It’s mostly related to the gastrointestinal tract. “Lactose intolerance, or lacking the enzyme to digest lactose, is an example of a food intolerance, along with histamine intolerance and MSG intolerance,” says Dr. Barish. Gas, bloating, constipation and diarrhea are common symptoms.

How long it takes for symptoms to appear: "Symptoms appear soon after eating or drinking whatever food it is you’re intolerant to,” says Dr. Barish. “It’s a bit easier to pinpoint than food sensitivities.”

How to diagnose it: You can get a breath test to diagnose lactose intolerance, says Dr. Barish. Other food intolerances are usually diagnosed by eliminating the food, monitoring your symptoms and reintroducing it to see if symptoms reappear.

How to treat it: Eliminate the food from your diet. Luckily, if you’re lactose intolerant, there are many dairy-free alternatives to choose from, like almond milk, coconut milk and oat milk. Certain dietary supplements and digestive enzymes can also be helpful, Dr. Barish adds.

Celiac Disease

What it is: Celiac disease is an autoimmune disease that’s triggered by eating gluten in those who are genetically susceptible. “A non-celiac gluten sensitivity doesn’t cause significant structural damage, but celiac disease damages the lining of gastrointestinal tract in the small bowel,” says Dr. Barish. Diarrhea, vomiting, constipation, bloating, anemia, malabsorption, chronic fatigue, weight gain and headaches are symptoms of celiac disease.

How long it takes for symptoms to appear: “There’s a lot of variability in the length of time it takes symptoms to appear,” says Dr. Barish. About 1% of the population has celiac disease, he says, and it’s underdiagnosed, so there are people with symptoms who haven’t been diagnosed.

How to diagnose it: “A small bowel biopsy is the best test to diagnose celiac disease, and certain blood tests can be useful screening tools as well,” says Dr. Barish. “Because it’s an autoimmune disease, celiac can be more common in people with other autoimmune conditions, such as certain thyroid conditions. Sometimes it’s just worth checking for celiac based on that alone.” 

How to treat it: Following a gluten-free diet is an essential component to ease symptoms and reverse damage. Fortunately, there are many gluten-free alternatives in the bread and pastry departments—and even pizza for when you need your Friday-night fix.