Food intolerances are on the rise. Today more than nine million adults suffer from food allergies. The Internet is rife with ads for “food sensitivity” testing kits, and some health care providers offer quick testing to find the foods that ail you. However, many tests can give false results, which may do more harm than good.
Common Food Sensitivities
Food Sensitivities Defined. There is no commonly accepted definition for food sensitivity. It’s often used interchangeably with food intolerance, which occurs when a food or ingredient is poorly absorbed in the digestive tract, and results in an adverse reaction, such as bloating, diarrhea, skin rashes, or hives. Occasionally, food intolerances can be caused by an enzyme deficiency, which can become more common with age. Food intolerances usually depend on the portion, meaning the risky food can typically be tolerated in small quantities. Although symptoms can be like those of a food allergy, the two are not the same. A food allergy is the result of an immune response: the body recognizes the food as a threat, which results in a range of symptoms, from mild like hives or itchy mouth, to serious like difficulty breathing or even death.
Pinpointing a Food Intolerance. A food intolerance can be difficult to diagnose because small amounts of the food may not cause adverse symptoms, and there are very few clinical tests that diagnose food intolerances. A popular test on the Internet and among naturopaths is serum immunoglobulin E (igE), which measures the amount of antibodies in the blood as a reaction to a specific food substance. However, the National Institute of Allergy and Infectious Diseases (NIAID) recommends against this test, as it has a high false-positive rate and dietary modification is not necessary if there are no signs or symptoms. The NIAID also recommends against basophil histamine release/activation, lymphocyte stimulation, hair analysis, allergen-specific IgG, cytotoxicity assays, electro-dermal test (Vega), and mediator release assay (LEAP diet) food sensitivity testing, because they lack scientific evidence.
The best way to determine a food intolerance is to keep a food diary, tracking all foods eaten, portion sizes, and a list of symptoms that occur afterwards. After two to four weeks, determine any patterns or connections between foods, portion sizes, and symptoms. Then, eliminate all distrusted foods for a week and re-introduce one at a time to examine your reaction. Consult a registered dietitian to guide the elimination process, ensure all nutrient needs are met, and assist in finding alternatives to replace banished foods.
—Esther L. Ellis, MS, RD, LDN