Do you regularly experiencing stomach or digestive issues after eating certain foods? Depending on the foods leading to your discomfort and symptoms, you may have a food allergy or intolerance. UnityPoint Health Dietitian, Allison Rossow, RDLD, breaks down the differences between food allergies and intolerances, plus steps to get tested.
Most Common Food Allergies
“A true food allergy causes an immune system reaction that affects numerous organs in the body,” Rossow says. “Food allergies cause a range of symptoms, and in some cases, an allergic food reaction can be severe or life-threatening. In contrast, food intolerance symptoms are generally less serious and often limited to digestive problems.”
Rossow says these eight foods account for 90 percent of food allergies:
- Dairy milk
- Wheat (gluten)
- Tree nuts (cashews, walnuts, pistachios and others)
The most common food intolerance is lactose intolerance. Lactose intolerance results from a deficiency of an enzyme that helps breakdown the lactose (sugar) found in milk.
Food Allergy Symptoms
Most food allergies develop in children 6 years old or younger, but they can occur for the first time at any age, including adulthood. Rossow says it isn't clear why, but some adults develop an allergy to a food they used to eat with no problem. Similarly, sometimes a child outgrows a food allergy only to have it reappear in adulthood.
Common food allergy symptoms include:
- Itchy mouth
- Swelling of the lips, tongue and throat
- Vomiting, diarrhea, abdominal cramps and pain
- Hives, itchy rashes
- Persistent eczema
- Tightening of the throat, trouble breathing, wheezing, coughing
- Sneezing, hoarseness, nasal congestion
- Drop in blood pressure, fainting, weak pulse
- A severe allergic reaction, known as anaphylaxis
Food intolerance symptoms are often limited to digestive problems, like stomach cramps, diarrhea, etc.
Am I Lactose Intolerant?
Dairy foods are a common trigger of food sensitivity, and Rossow says your doctor may suspect lactose intolerance based on your symptoms and response to reducing dairy foods in your diet. Doctors confirm a lactose intolerant diagnosis by one or more of the following tests:
- Lactose tolerance test. Gauges the body's reaction to liquid containing high levels of lactose. Two hours after drinking the liquid, blood tests are done to measure the amount of glucose in the bloodstream. If the glucose level doesn't rise, it means the body isn't properly digesting and absorbing the lactose-filled drink.
- Hydrogen breath test. Measures the amount of hydrogen in breath. This test also requires you to drink a liquid that contains high levels of lactose. Normally, very little hydrogen is detectable. However, if the body doesn't digest the lactose, it will ferment in the colon, releasing hydrogen and other gases, which are absorbed by the intestines and eventually exhaled. Larger than normal amounts of exhaled hydrogen measured during a breath test indicate not fully digested and absorbed lactose.
- Stool acidity test. For infants and children who can't undergo other tests, a stool acidity test may be used. The fermenting of undigested lactose creates lactic acid and other acids that can be detected in a stool sample.
Types of Testing for Food Allergy and Intolerance
Rossow says the first step an allergist will take to diagnose a food allergy is a thorough medical history. The allergist will ask questions to determine if a food allergy may be causing symptoms and to identify the culprit food(s) before performing a physical exam. Next, the allergist may conduct allergy tests to help identify a specific food allergy. While these tests alone do not always provide clear-cut answers, the allergist will combine test results with the information given in your medical history to provide a diagnosis. These tests may include:
- Skin prick test
- Blood test
- Oral food challenge
- Trial elimination diet
Depending on your medical history and initial test results, you may have to have more than one test before receiving your diagnosis.
Food Allergy and Intolerance Treatment
Unfortunately, Rossow says the only way to avoid an allergic reaction is to avoid the food(s) causing signs and symptoms.
“For a minor allergic reaction, over-the-counter or prescribed antihistamines may help reduce symptoms. But, for a severe allergic reaction, an emergency injection of epinephrine may be needed. If you have a food intolerance, your doctor may recommend steps to aid digestion of certain foods or to treat the underlying condition causing your reaction,” Rossow says.
Managing food allergies and intolerances can mean making dietary changes. Those with food allergies must strictly avoid the offending food(s), which requires careful reading of food labels and ingredients lists. A person with a food intolerance may or may not be able to eat small amounts of the offending food without trouble. But, before making any large-scale lifestyle changes, Rossow encourages seeing a provider.
“Do not diagnose a food allergy on your own. Self-diagnosis can lead to unnecessary dietary restrictions and inadequate nutrition, especially in children. If you have a reaction after eating a particular food, see your doctor to determine whether you have a food allergy or intolerance,” Rossow says.
Other Topics from Our Experts: