An intolerance to certain foods can cause some of the same signs and symptoms as food allergy, so people often confuse the two. Physical reactions to certain foods are common and some are caused by food intolerance rather than food allergy.
A true food allergy causes an immune system reaction that affects numerous organs in the body. It can cause a range of symptoms. In some cases, an allergic reaction to a food can be severe or life-threatening. In contrast, food intolerance symptoms are generally less serious and often limited to digestive problems.
If you have food intolerance, you may be able to eat small amounts of the offending food without trouble. You may also be able to prevent a reaction with certain medications.
Causes of Food Intolerance
Lactose is a sugar found in milk and most milk products. Lactase is an enzyme in the lining of the gut that breaks down or digests lactose. Lactose intolerance occurs when lactase is missing. Instead of the enzyme breaking down the sugar, bacteria in the gut breaks it down, which forms gas, which in turn causes symptoms of bloating, abdominal pain and, sometimes diarrhea.
Lactose intolerance is uncommon in babies and young children under the age of 5 years. Because lactase levels decline as people get older, lactose intolerance becomes more common with age. Lactose intolerance also varies widely based on racial and ethnic background. Your doctor or allergist can use laboratory tests to find out whether your body can digest lactose.
Gluten is a part of wheat, barley, and rye. Gluten intolerance is associated with Celiac disease, also called gluten-sensitive enteropathy. This disease develops when the immune system responds abnormally to gluten. This abnormal response does not involve IgE antibody and is not considered a food allergy. Celiac disease has some features of a true food allergy because it involves the immune system. However, symptoms are mostly gastrointestinal, and people with celiac disease are not at risk of anaphylaxis.
Food Additive Intolerance
Another type of food intolerance is a reaction to certain products that are added to food to enhance taste, add color, or protect against the growth of microbes. Sulfites are added to food to increase crispness or prevent mold growth. They occur naturally in the food during the winemaking process. Sulfites can cause breathing problems in people with asthma. The FDA has banned sulfites as spray-on preservatives for fresh fruits and vegetables. When sulfites are present in foods, they must be listed on ingredient labels.
Some of the symptoms of food allergy, such as abdominal cramping, are common to food poisoning. However, food poisoning is caused by microbes, such as bacteria, and bacterial products, such as toxins, that can contaminate meats and dairy products.
Scromboid Fish Poisoning
Fish, such as tuna and mackerel that are not refrigerated properly and become contaminated by bacteria, may contain very high levels of histamine. A person who eats such fish may show symptoms that are similar to food allergy. However, this reaction is not a true allergic reaction. Instead, the reaction is called histamine toxicity or scombroid food poisoning.
Several other conditions, such as ulcers and cancers of the gastrointestinal (GI) tract, cause some of the same symptoms as food allergy. These symptoms, which include vomiting, diarrhea, and cramping abdominal pain, become worse when you eat.
Other examples of food intolerance symptoms include: insomnia from caffeine, gas from beans, runny nose from peppers. There are also symptoms that are never allergy related, such as constipation, joint pain and fever. Headache is never an allergy unless there are also respiratory or nasal symptoms or hives.
Always rely on the professional guidance of your doctor or allergist to determine if you have food allergy or a food intolerance. There are available treatments and medications for both.