How to Pinpoint Food Allergies

Keep a Food Diary

Track everything you eat for at least 2 weeks. If you're unsure which particular foods seem to cause problems for you, keep a food diary for two or more weeks. Having a record of foods and symptoms can help you associate particular foods or ingredients with particular reactions. Once you have an idea of a few foods that may be causing discomfort, you can try elimination diets or formal allergy testing at an allergist's office.

Write down everything you eat and drink. It is essential to have a complete record of everything you consume during the weeks of your food diary. Continue to eat your regular diet, but carry a small notepad or use the notes function on your smartphone to record snacks, vending machine purchases, and other drinks or bites to eat you may have throughout the day. Include all ingredients. For example, if you eat an oatmeal cookie, write down all ingredients or save the ingredient list if the cookie is store-bought. This will help you pinpoint which food causes issues. You should be able to distinguish between an oat and an egg intolerance by knowing exactly what everything you eat contains and performing an elimination and reintroduction later, as long as it is safe to do so.

Carefully record the timing, type, and severity of reactions. In some cases, food intolerance can be confused with actual allergic reactions, and temporal reactions may point to the wrong offender foods. Write down the details of symptoms such as itchiness, swelling, hives, stomach discomfort, diarrhea, nausea, cramps, fever, and any other reactions of the skin or gastrointestinal tract. This will help identify the type of sensitivity you have and the management techniques that will be most appropriate for your food intolerance or allergy.

Discuss your findings with a dietitian or health care provider. Once you have a detailed food diary, you can discuss potential offending foods with a nutrition specialist or allergist to identify particular foods to avoid or strategies to reduce reactions.

Perform an Elimination Diet or Challenge Test

Talk to your doctor about an elimination diet. Once you have collected thorough information about your diet and symptoms and have discussed it with a medical or nutritional professional, consider performing an elimination diet or challenge test to pinpoint particular food issues. If you experience anaphylaxis from any foods at all, do not attempt to perform an elimination diet or oral challenge without the supervision of a physician. If your reactions are typically mild or nondescript, however, an elimination diet or oral challenge can help narrow the list of possibilities.

Select a list of foods to eliminate. After carefully reviewing your food journal for foods that appear to be related to symptoms, make a list of foods to eliminate entirely from your diet, albeit temporarily. Unless you suspect an allergy or an intolerance to a very pervasive ingredient, such as wheat or dairy, avoid dramatically restricting your daily diet by selecting no more than 5 individual foods to eliminate at a time.

Begin the elimination diet by strictly avoiding the selected foods for 3 to 4 weeks. Continue recording your diet and symptoms during this time. If symptoms have subsided or disappeared, add one food each week back into your diet and continue to track reactions. If the re-introduced food causes no reaction for the entire week, cross it off your list of potential intolerances and introduce the next food the following week. Continue this way until you have identified the particular food or foods that cause reactions, avoiding them and discontinuing the challenge for the week if your symptoms return. Be thorough when eliminating foods. For instance, if you suspect that honey is the ingredient that causes symptoms, check labels for cookies, sauces, cereals, flavored nuts, bottled teas. If you eat a lot of pre-packaged or prepared items, always check ingredient labels to see whether foods you might not suspect could possibly contain the potential ingredient.

Keep track of all foods that cause reactions upon reintroduction. Make a list of the food that caused symptoms and keep the food out of your daily diet until you can discuss the reactions with a health professional or get tested for the specific food. If you experienced a reaction from a food with more than one ingredient, write down all ingredients in the food item, including additives, preservatives, dyes, and nutritional supplements. Although applesauce, mustard, or soda may seem to be the trigger, the offender could really be a spice, food additive, or sugar substitute.

Repeat the process if necessary until reactions disappear. If you continue to experience symptoms, albeit reduced in severity or frequency, it is possible you identified the majority of offenders in your diet or that you missed hidden triggers that are present in processed foods. If you need help tweaking your elimination diet, consult a dietician or a physician like an allergist for advice. In some cases, they may be able to examine your list of suspect foods and your food diary to identify potential areas for experimentation. For example, a nutritionist may be able to look at your notes and identify offending food groups or types (such as seeded fruits or emulsifiers in sauces), cross-contamination (often with nuts or grains), or incomplete elimination (due to hidden sources of the offending ingredient or multiple published names of ingredients on food labels).

Perform an oral challenge test if you believe you have an intolerance to a food. An oral challenge test involves consuming small but increasing portions of a single food, allowing time in between increasing doses to detect reactions. If no reaction is experienced, an increased amount is consumed. If you experience swelling, hives, or any symptoms of anaphylaxis upon eating certain foods, do not perform an oral challenge test without the direct supervision of a physician or allergy specialist. Only one specific food is tested at a time in oral challenge tests to avoid confusion with other potential food sensitivities. Do not perform more than one oral challenge test per week unless under the supervision of a health professional.

Get Tested for Food Allergies

Seek a test if you're still unsure and for the sake of certainty. In many cases, it can be difficult to pinpoint food intolerances. If you have already performed a food diary exercise and an elimination diet or oral challenge, set up an appointment with an allergist, who may be able to specify potential allergens through skin prick tests or blood tests. They can also educate you on the differences between food allergies and intolerances. In cases of mild or variable reactions to foods, using your history is the most important part of the diagnosis.

Speak with an allergist to find out if you require skin prick testing. In most cases, skin prick tests can be performed quickly and safely in the office of an allergy specialist. Skin prick tests involve inserting tiny amounts of potential offenders under the surface of the skin. If a bump appears, it indicates that you're sensitized to that food, which may lead to a food allergy diagnosis.

Ask your allergist whether you require a blood allergy test. A blood allergy test involves a small blood draw that will be sent to a laboratory for testing. It can take several weeks to get results. Blood tests and skin prick tests may be helpful for determining if you're allergic to certain foods. Talk to your allergist to see if either is right for you.