A food allergy is an immediate or delayed adverse reaction to the ingestion of specific foods. Common signs and symptoms which point to such allergies include dark circles and puffiness under the eyes, chronic diarrhea, inflammation of various types, headaches (including migraine), chronic runny nose, itchy eyes, asthma, hives, poor digestion, mental and physical fatigue, skin conditions, inflammatory diseases, and chronic infections.

Holistic physicians and traditional physicians differ on their definitions of allergy, with holistic doctors including not only standard allergy, but also abnormal responses to foods, food intolerance, abnormal metabolic reactions to foods and pharmacological food reactions. These may not show on standard IgE tests.

Food allergy sensitivity usually forms slowly by repetitive eating of a food. Food allergies have been linked to a wide variety of diseases, including those affecting the following systems: gastrointestinal, genitourinary, immune, mental, emotional, musculoskeletal, skin, respiratory, membrane and heart.

To test for a hidden food allergy, completely remove the item from your diet for two full weeks, making sure to real all labels of foods to ensure compliance. Then, eat a medium to large amount of the food in question. If the re-introduction of the food causes a noticeable adverse reaction over the next 24-48 hours, you are allergic to it, and must remove it from your diet. Common reactions are headache, nausea, feeling "hyper", hives or skin itching, fatigue, irritability, bags under the eyes and insomnia.

The two week period allows the body to mount a stronger response, making it easier to identify. If there is no response, you are not allergic to this food, and may consume it freely. If your are unsure of your response, you may re-test.

Once the food is eliminated, after 3-6 months, many people find they can eat the food occasionally--not more than once every four or five days--without event. Eating the food for several days in a row will probably re-activate the allergy and cause a return of symptoms.

Although any food substance can cause problems, the following foods are the most common causes of food allergy:

Cow’s milk, wheat, corn, chocolate, egg, orange, benzoic acid, cheese, tomato, rye, rice, fish, grapes, onion, soy products, pork, peanut, alcohol, MSG, walnut, beef, tea, coffee, nuts, oats, sugar, yeast, apple, peach, potato, chicken, banana, strawberry, melon, carrot.

It is also possible to react to an entire class of foods, such as milk products, citrus fruits, nuts and chemical preservatives. Finally, remember to check all labels of foods you eat, to make sure none of the foods you are allergic to are hidden in the ingredients.