By Savannah Miller, USOC Nutrition Intern
Researchers have estimated more than 15 million Americans and 300 million individuals worldwide are currently suffering from food allergies. Statistics have also shown there to be a large gap between the number of people who think they have a food allergy and the number of people who are actually diagnosed as allergic. It is extremely important that allergy testing be done through evidence based practices. This helps prevent unnecessary over-restrictions of an athlete’s diet, which makes it difficult to diversify foods for adequate fueling and recovery at mealtimes, training and competition. Over-restrictions of the diet can lead to challenges with sufficient intake to support performance, including nutritional deficiencies, inadequate fueling, limited food options, higher food costs and increased anxiety when dining out and traveling.
Adverse reactions to foods are generally attributed to an allergy, but more often are due to a food intolerance or sensitivity. A food allergy is an adverse immune response to exposure of a food. Our immune system will make antibodies to protect itself from germs and disease, but it may also make antibodies in response to certain food proteins. Some of these antibodies (called IgE) are known to be associated with allergic reactions. When that happens, the immune system will treat a food as if it were a harmful substance, resulting in an allergic reaction. IgE-mediated food allergies are the most common and dangerous type of adverse food reaction. The most common food allergens in the United States include eggs, milk, peanuts, tree nuts, wheat, crustacean shellfish and soy. Food allergies may produce negative respiratory, gastrointestinal, cutaneous and cardiovascular symptoms. If present, life-threatening symptoms manifest at a rapid rate resulting in anaphylactic shock. Symptoms tend to occur just after eating, inhaling or coming into contact with the offending food. Other symptoms can include reddening of the skin, hives, itchy skin, swollen lips or eyelids, tightness of the throat, wheezing, difficulty breathing, coughing, vomiting or diarrhea.
A food intolerance is a non-immune mediated adverse reaction to foods. Food intolerances are principally caused by enzymatic deficits in the digestive system or an inappropriate response to a certain food chemical. The symptoms of food intolerances and sensitivities are generally less serious than food allergy symptoms and are often limited to digestive, nasal or skin symptoms. Symptoms are often dose-related, meaning that you may be able to eat small amounts of the offending food without symptoms. You may also be able to prevent a reaction. For example, if you have a lactose intolerance, you may be able to drink lactose-free milk or take a lactase enzyme pill (e.g. Lactaid) to help digest the lactose.
Celiac disease is an example of a food allergy whereas gluten or wheat sensitivity is an example of a food intolerance. Celiac disease requires a medical diagnosis as it requires a strict gluten-free diet for life and has long term health consequences if not compliant. In contrast, gluten sensitivity can be managed according to symptoms, whereby ingesting small amounts of gluten may not result in any symptoms or lead to any long-term health concerns.
There are several tests an athlete may undergo in order to determine if they have a food allergy or intolerance; however not all are accurate. Below are common tests:
| Description | Is this Recommended? | |
| Skin Prick Testing | Frequently used as an early confirmation of a food allergy. This involves introducing the allergenic protein into the upper layer of skin. Skin is then monitored for a reaction. | Recommended. May test up to 40 different substances at once. This test is usually done to identify allergies to pollen, mold, pet dander, dust mites and foods. |
| ALCAT | Antigen leukocyte antibody test claims to measure adverse reactions to dietary substances | Not recommended. Non-evidence based and non-valid. |
| Blood Test (IgE) | Used for measuring the number of antibodies found in the blood
IgE blood tests measure the presence of IgE antibodies to specific foods. IgE, short for “immunoglobulin E,” is the antibody that triggers food allergy symptoms. |
Recommended and accurate. Precautions prior to test must be met to be accurate. For example, someone with celiac disease would have to be consuming gluten daily for at least two weeks before being tested. |
| Blood Test (IgG) | Used for measuring the number of antibodies found in the blood
IgG blood tests measure the IgG antibodies of specific food intolerances and sensitivities, not allergies. |
Not recommended. Non-evidence based and non-valid. The diagnostic results for determining food sensitivities/intolerances based on these results is poor. Positive IgG results can easily indicate a food that has been eaten regularly as much as it might indicate a food intolerance. By eating more of a food, our immune system creates a greater tolerance to it, and thus produces higher IgG levels. |
| Double Blind, Placebo Controlled Food Challenge | Gold standard for diagnosing a true food allergy. The test attempts to reproduce the history of food-induced symptoms described by the patient. Precautions that must be taken are delineated before challenge, as is treatment that may be required if a reaction occurs. | Recommended and accurate. However, must be taken under medical supervision because they have a high potential to produce severe reactions. |
| LEAP-MRT | Includes a patented blood test called MRT (Mediator Release Test) LEAP stands for Lifestyle, Eating and Performance. It’s a diet plan specifically tailored to each person to calm down the immune system and eliminate symptoms associated with food sensitivities. | Not recommended for diagnosing a food allergy. Non-evidence based. |
| Fecal test | Stool analysis is a series of tests done on a stool (feces) sample to help diagnose certain conditions affecting the digestive tract. | Expensive but productive in ruling out bacterial issues.
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| Gasto-intestinal biopsy | A procedure that allows your doctor to look at the inside lining of your esophagus, your stomach, and the first part of your small intestine to look for ulcers, inflammation, tumors, infection, or bleeding. Can collect tissue samples (biopsy), remove polyps, and treat bleeding through the scope. They can look for signs of certain allergies. | Highly recommended for celiac disease (the gold standard test for celiac disease), but time consuming and expensive. |
If you suspect that you may have a food allergy or intolerance, it is highly recommended that you contact a doctor and speak with a sport dietitian before restricting any foods. Accurate diagnosis of a food allergy should include detailed and consistent medical history, physical examination and valid clinical diagnostic testing. The most highly recommended tests include the IgE blood test and the skin prick test. However, certain precautions for blood tests must be met prior to testing to experience accurate results. Tests also need to be partnered with a change of symptoms. If a food allergy or intolerance is found to be present, your sport dietitian can help ensure you maintain a nutritionally balanced diet and achieve all your training needs.