Food allergy is a controversial and misunderstood area of medicine. There is significant disagreement among physicians about diseases caused by food "allergy." Many physicians outside the specialty of allergy have not been taught to think about adverse reactions to foods as a cause of their patients' problems. Recently, more scientific work has proven the relationship of food allergy to diseases other than the usual allergic diseases such as asthma, nasal disease, and hives. There is ongoing research that will help us understand the possible role of things we eat in migraines, rheumatoid arthritis, colitis, and other human ailments.

Many ideas on food allergy have been presented to the public in newspapers, on TV talk shows, and in books. These sources have alerted patients to a vast number of possible adverse reactions to things they eat. Many of these ideas have not been subjected to adequate scientific investigation and leave sincere physicians as confused as their patients in some instances.

In the specialty of allergy and immunology, however, physicians are highly attuned to the problem of adverse food reactions and have developed a scientific framework to evaluate the role of foods in medical problems.

Understanding the Categories of Food Reactions

What is commonly called "food allergy" can be broken down into more specific categories:

Adverse Food Reactions

Any illness or reaction caused by eating a food or foodstuff.
Food Intolerance

In this case, a normal body enzyme or function may be deficient or abnormal. For example, a large number of people have trouble digesting milk sugar. When they drink milk, they experience stomach pains and diarrhea as the milk sugar is digested by intestinal bacteria rather than by the person.
Food Hypersensitivity

This is of two types. In one type, people react in an unusual way to chemicals — for example, having an asthma attack or hives when eating foods treated with metabisulfite. The second type most resembles usual allergy, though it may be more complicated. This type is caused by an immune response, and in some cases involves the same class of allergic antibodies found in pollen, mold, or dust allergy.

Diseases Associated With Food Allergy

The following diseases have considerable evidence supporting a causative role of foods:

Asthma
Nasal problems
Hives
Eczema
Migraines
Diarrhea
Vomiting
Abdominal pain
Anaphylaxis
Swelling (angioedema)

The following conditions have been speculated to have food-related causes, though scientific evidence is much less established:

Bedwetting
Sluggishness/tiredness
Inability to concentrate
Hyperactivity
Constipation
Mouth ulcers
Foul breath
Dizziness (Meniere's syndrome)
Pruritus ani
Fever
Nervousness
Heartburn/belching
Joint pain
Muscle pains
Joint swelling
Irregular heartbeats
Numbness/tingling
Colitis

The Blind Challenge

A powerful diagnostic tool called the "blind challenge" has made it possible to objectively evaluate the role of foods in a patient's problems — including those in the second list above.

Guided by your medical history, allergy testing, and response to an avoidance diet, this tool clearly identifies the effect of a food or foodstuff on your health. In this technique, you will receive either foods or a placebo (nonactive substances) encased in opaque capsules or other masking vehicles. The exact form of the challenge may vary based on your individual clinical history, but a typical challenge proceeds as follows:

Day One
You will come to the office and receive an increasing number of opaque capsules containing either powdered (freeze-dried) food or placebo. You will stay in the office for a period of observation and then be dismissed with a diary sheet to continue your own observation at home.

Day Two
You will return and again be observed while receiving a number of capsules. The entire procedure is repeated. If at any time you develop symptoms requiring treatment, you will be treated appropriately.

The nurse administering the packets will not know their contents, so that her expectations cannot influence the challenge. Similarly, any expectations or beliefs you have are checked by inclusion of the placebo. The physician will know the contents of the challenge packets for your protection. The goal of the challenge is to reproduce, in a modified and smaller way, some of your symptoms.

By discovering the exact role of foods in your problems, we can plan a program to help you get well and stay well.