Food Intolerance

Unpleasant symptoms occurring after ingestion of a food could be due to a food allergy or food intolerance.

What is the difference between a food allergy and a food intolerance? Is it necessary or important to distinguish between the two terms? How is the food allergy or intolerance diagnosis established? Are these conditions managed differently?

The term “allergy” traditionally refers to a phenomenon where the immune system considers a substance as “foreign” and subsequently mounts a defensive attack against it. The symptoms of these allergic reactions are caused by the release of a variety of chemical mediators of inflammation such as histamine, prostaglandins, and leukotrienes, to name a few.

These allergic reactions can be mediated by either the humoral (i.e. antibodies are involved) or the cellular (i.e., lymphocytes are involved) arms of the immune system. The IgE antibody-mediated (i.e., humoral-mediated) reactions usually produce symptoms within minutes of exposure to the offending agent. The typical symptoms may include itching, sneezing, hives, swelling of soft tissues (e.g., lips, tongue, throat), and/or difficulty in breathing. These reactions are usually more severe and can occasionally be life-threatening. The lymphocyte-mediated (i.e., cell-mediated reactions), on the other hand, are also called delayed hypersensitivity reactions, as the symptoms usually appear a few days after the exposure to the triggering agents. An example of a delayed hypersensitivity reaction is an allergic reaction that occurs due to contact with a chemical or metal. In most cases of this type of contact dermatitis, skin manifestations in the form of itching and/or a rash occur.

Food “intolerance” usually denotes a difficulty in processing the food by the gastrointestinal tract. Sometimes the term “food sensitivity” is used instead of food intolerance. Various enzymes are needed in order to break down the proteins, sugars and fats in the food we eat. When there is a deficiency of an enzyme needed to breakdown food, that food will not be properly digested. As a result, bothersome symptoms such as abdominal pain/discomfort, abdominal bloating, nausea, diarrhea, and/or constipation after eating may occur.

Lactose intolerance is a common example of a food intolerance. Lactose is the sugar found in dairy products and it requires the enzyme called lactase in order to digest it. Many adults do not have enough lactase to process the lactose, and as a result, the undigested sugars become fermented in the intestines which then in turn may cause increased gas production. Thus, the symptoms associated with lactose intolerance may include abdominal bloating, flatulence, abdominal pain, and/or diarrhea after the consumption of dairy products.

Gluten is a protein found in wheat, barley and rye. Gluten helps foods hold their shapes such as breads, pasta, and cereals. Many individuals have an intolerance to gluten because they cannot process it well in their digestive tracts. This intolerance to gluten may result in symptoms such as abdominal discomfort/pain, abdominal bloating, nausea, diarrhea, and/or constipation.

Celiac disease is an immunologically mediated disorder where antibodies cause damage to the lining of the small intestine leading to difficulty in digesting gluten. This condition causes a variety of symptoms and is suspected by elevated antibody levels in the blood and confirmed by a biopsy of intestinal mucosa.

The diagnosis of food allergy is established by the demonstration of specific antibodies to proteins in the food, either by skin prick tests with various food antigens or by laboratory evaluation of an individual’s blood sample. The food skin prick tests and the blood tests are typically negative in cases of food intolerance.

The management of food allergy involves the complete elimination of the offending food from the diet, particularly since there is a possibility of severe adverse reactions in food-allergic individuals. In addition to avoiding the offending food, a self-injectable epinephrine device (e.g., EpiPen, Auvi-Q, Adrenaclick) is usually prescribed depending on the severity of the allergic reaction described by the food allergy sufferer. If the self-injectable epinephrine device is ever used, one should go immediately to the closest emergency room.

It is important to note that there are desensitization protocols for certain foods which may enable the development of tolerance to allergic protein. This process is called oral immunotherapy or oral desensitization. Oral food desensitization helps reduce the risks of severe food reactions occurring after accidental exposures. Even if an individual is undergoing oral immunotherapy, a self-injectable epinephrine device (e.g., EpiPen, Auvi-Q, Adrenaclick) will be prescribed. If it is ever used then one should go immediately to the closest emergency room.
The management of food intolerance also involves avoidance of the suspected foods to the extent possible while substituting with other foods which are better tolerated to ensure adequate nutrition.

Lactose intolerance can be managed by the substitution of lactose-free dairy products in the diet and/or supplementation of the lactase enzyme (available in powder and pill forms such as Lactaid) when lactose-containing foods are consumed.

The board certified allergists at Black & Kletz Allergy have been diagnosing and treating food allergies and food sensitivities for more than 50 years in the Washington, DC, Northern Virginia, and Maryland metropolitan area. We have convenient locations in Washington, DC, McLean, VA (Tysons Corner, VA), and Manassas, VA. Each office has on-site parking. The Washington, DC and McLean, VA offices are Metro accessible and there is a free shuttle that runs between our McLean, VA office and the Spring Hill metro station on the silver line. Please call for an appointment if you would like a consultation with one of our allergists, or alternatively, you can click Request an Appointment and we will respond within 24 hours by the next business day. Black & Kletz Allergy prides itself in providing quality allergy, asthma, and immunology care to the Washington, DC, Northern Virginia, and Maryland metropolitan area community.