Food allergy vs. food intolerance: What's the difference?

Food allergy vs. food intolerance: What's the difference? Question Food allergy vs. food intolerance: What's the difference? What's the difference between a food intolerance and food allergy? Answer from James T. Li, M.D. Although many people have adverse reactions to certain foods, most are caused by a food intolerance and not a food allergy. Less than 8 percent of children under age 3 and about 4 percent of adults have a true food allergy. Food intolerance is much more common. Because a food intolerance can cause some of the same signs and symptoms as a food allergy, people often confuse the two. A true food allergy can cause a tingling mouth, hives, swelling of the lips, face, tongue and throat, trouble breathing, and dizziness or fainting. It can also cause nausea, vomiting, cramping and diarrhea — signs and symptoms that often occur with a food intolerance as well. With a true food allergy, a cascade of steps occur that condition your body to respond to certain foods: Your immune system mistakenly identifies a specific food as a harmful substance. Your body produces antibodies to fight the culprit food. The next time you eat even the smallest amount of that food, the antibodies sense it and alert your immune system. Your immune system then releases histamine and other chemicals into your bloodstream, leading to food allergy symptoms. Unlike a food allergy, a food intolerance generally doesn't involve the immune system. If you have a food intolerance, you can probably eat small amounts of the food without a reaction. By contrast, if you have a food allergy, eating even the tiniest amount of the food may trigger a serious allergic reaction. Common food intolerance conditions that are often mistaken for food allergies include: Absence of an enzyme needed to fully digest a food. A common example is lactose intolerance — which can cause bloating, cramping, diarrhea and excess gas. Irritable bowel syndrome. This chronic condition can cause cramping, constipation and diarrhea. Food poisoning. Commonly caused by consuming bacteria in spoiled food or other toxins, food poisoning can cause severe digestive symptoms. Sensitivity to food additives. Some people have digestive reactions and other symptoms after eating certain food additives. For example, sulfites used to preserve dried fruit, canned goods and wine can trigger asthma attacks in sensitive people. Recurring stress or psychological factors. Sometimes the mere thought of a food may make you sick. The reason is not fully understood. Celiac disease. This chronic digestive condition is triggered by eating gluten, a protein found in bread, pasta, cookies, and many other foods containing wheat, barley or rye. Signs and symptoms of celiac disease include diarrhea, abdominal pain and bloating. While celiac disease involves an immune system response, it's a more complex food reaction than a food allergy. If you have a reaction to a particular food or foods, talk to your doctor about it. It's important to determine whether you have a food intolerance, or whether your symptoms are caused by a true food allergy. While a food intolerance can make you miserable, food allergies are generally more dangerous. They're the most common cause of life-threatening allergic reactions. If you do have a food allergy, you'll need to take steps to avoid the allergy-causing food and be prepared to respond to an allergic reaction.