Overview of Food Intolerances:
The term food intolerance is fairly broad and is sometimes used interchangeably with food sensitivity. In general, a food intolerance refers to unpleasant food-triggered symptoms -- often, though not always, gastrointestinal in nature -- that are not IgE-mediated reactions of the immune system. Some people do refer to food intolerances as allergies, but this is incorrect; intolerances, even severe ones, are not true allergies.
Common Food Intolerances:
The two most well-known -- and, perhaps, most common -- food intolerances are lactose intolerance and celiac disease. Lactose intolerance is caused by the lack of a digestive enzyme necessary to process a sugar found in milk, while celiac disease is an autoimmune disorder triggered by a protein found in wheat, rye, and barley. Both commonly cause gastrointestinal symptoms, although celiac disease can cause many other symptoms, too.
Symptoms of Food Intolerances:
Because food intolerance is such a broad term, symptoms of food intolerances can vary greatly. Diarrhea, constipation, bloating, flatulence, and nausea are all possible food intolerance symptoms. Less often, people with food intolerances report headaches, malaise, or other symptoms that improve when they remove the offending food from their diet.
Diagnosing Food Intolerances:
The two most common food intolerances have specific diagnostic tests. A breath test or stool test can diagnose lactose intolerance (although, in some cases, a history and informal dietary challenge will suffice), and a blood test confirmed by an endoscopy is the test for celiac disease. Many other intolerances do not have specific tests, so your doctor may track your diet or temporarily restrict certain foods to gauge your body's response.
Treatment for Food Intolerances:
In most cases, if your doctor determines that food is causing your unpleasant symptoms, you will need to avoid the offending food. Sometimes, people with food intolerances can eat small amounts of problem foods, but this is not universally the case; those with celiac disease, for instance, need to abstain from gluten-containing foods for life. Lactose intolerance can be treated with supplements of the lactase enzyme missing from the body.
Related Conditions:
Some conditions that are affected by food intake are not, strictly speaking, food intolerances or allergies. Depending on your medical history and physical exam, your doctor may want to rule out ulcers, GERD, irritable bowel syndrome, inflammatory bowel disease, eosinophilic enteropathy, or other less common conditions.
Living with Food Intolerances:
In general, living with food intolerances is similar to living with other food allergies. The major differences are that there is normally no rescue medication available for treatment if you inadvertently eat some of the food you are sensitive to and that, in some cases, you may be able to eat small amounts of a food you have an intolerance to with little or no ill effect. (This is not always the case; those with celiac disease, for instance, need to maintain very strict gluten-free diets to avoid serious long-term complications of untreated celiac disease.)
If you are able to eat small quantities of a problem food, issues like cross-contamination may not be a major concern for you. However, you will still need to adapt your diet, whether you're eating at home or at a restaurant. Learning to recognize the names your trigger foods are listed under on food labels is one major step you can take to ensure good health.
Source:
Feldman, Mark, et al. Gastrointestinal and Liver Disease. 8th Ed. Philadelphia: Saunders Elsevier, 2006.
