Determining what foods are the cause of an allergic reaction is key to treatment. Before you identify the culinary culprit you must consider what type of food allergy your child has. There are two types of food allergies. They are classified as:

• Fixed food allergies: A fixed food allergy may be very apparent, such as the child whose lips swell and throat itches immediately in response to eating peanuts. The cause for this type of food allergy is similar to that of inhalant allergies, so the diagnosis is more easily reached. Blood testing (i.e., RAST test) is typically used to verify fixed food allergies. Approximately five to 15 percent of food allergies are of the fixed variety.
  
• Cyclic food allergies: These allergies are far more common but less understood. Delayed food allergy symptoms can take up to three days to appear. This type of reaction is associated with the body’s immunoglobin G (IgG) or antibodies. Unlike fixed food allergies, this allergic response is cyclical in nature. As an example, a child may be IgG sensitive to milk. Consequently, symptoms might appear if the child increases the intake and/or frequency of milk consumption.

Both children and adults are susceptible to food allergies. The bad news for children is that they often have more skin reactions to foods, such as eczema, than do adults. But the good news for the young patient is that a child often outgrows his or her food sensitivities, even those that are positive on a RAST test, over time. Food allergies may fade, and then inhalant (e.g, dust, ragweed) allergies may begin to manifest.

Diagnosing and treating the cyclic food allergy

If your child is experiencing allergic reactions to food of unknown origin, you should ask yourself, “Are there any foods that my child craves or any food that I avoid offering?” These foods may be the ones that are causing difficulties for the young patient.

Your physician may also suggest the Elimination and Challenge Diet.

This dietary test consists of the following steps:

1. Keep a detailed food diary tracking what was eaten (including ingredients), when it was eaten, medications taken, and any symptoms which developed.   Be honest! Some well-meaning parents or caregivers often create a food diary to look healthier than it typically is. Your child can receive the best diagnosis if the diet records are accurate, timed precisely, and truthful. The diet diary can be evaluated by an ear, nose, and throat specialist to identify one or several food items that may be the culprits.

2. Conduct an unblinded elimination and challenge diet at home based upon your physician’s assessment of your child’s diet diary. It is best if you carefully maintain a new diet diary for your child during the period of elimination and challenge. During this elimination and challenge diet, your child must abstain from one, and only one, of the possible food culprits at a time for a period of four days. This can be difficult to carry out if the food is very common, such eggs or cereal, so you need to pay strict attention to your child’s diet during the elimination phase. Any “cheating” will invalidate the results.

3. On the fifth day, you will be asked to feed your child the suspected culprit food item. This is the challenge! Provide your child an average-sized portion of the food in question to be eaten in five minutes. In one hour the child should eat another 1/2 portion if no symptoms have developed. Any symptoms that develop are then timed and recorded. With a true cyclic food allergy, you would expect a significant worsening of the symptoms described in the original diet diary, although the challenge symptoms may vary as well. Fixed food allergies should never be deliberately challenged unless under the direct supervision of a physician. For minor, moderate discomfort from the testing, the patient may take: 1) a child’s laxative to decrease the transit time through the digestive system, 2) Alka Seltzer Gold, 3) Buffered Vitamin C (one gram).

If the Elimination and Challenge Diet confirms a cyclic food allergy, then you will be asked to abstain from feeding your child this food for a period of three to six months. After this time you can slowly reintroduce the food on a rotary basis; it is not to be eaten more frequently than every four days (once or twice a week).