When Is A "Food Allergy" Really An Allergy?

Food allergies are often misunderstood. There is a great deal of general confusion about them, and they constitute a controversial area within the allergy field of medicine. Oftentimes, what is at first thought to be a food allergy is found to be something else. For example, many people who think they are allergic to foods are merely sensitive to these foods. Others may have enzyme deficiencies which cause them to react adversely to a food in a non-allergic way. In the following article, I hope conquer these and other common misunderstandings about food allergies one at a time.

The Classic Food Allergy

Let's look first at "true" (or "classic") food allergies and how to prevent and treat them. Classic food allergies include allergies to milk, soy, egg whites, shellfish and peanuts. Peanut allergy is a good example to examine, since it is one of the most widely known food allergies and is becoming more and more common. (It is also the food allergy most likely to be fatal). With classic food allergies, your body forms antibodies against the offending food. Even the smell of the food can cause a reaction in a highly allergic person. That's why peanut allergic persons do not like to fly in planes where nuts are served. I recently treated two different people who had severe reactions to peanuts while on a plane. Neither one of them had eaten peanuts and, in one case, the passengers within three rows of this person had offered to voluntarily abstain from eating any nuts. I suspect that either the smell permeated the cabin or some old peanut "dust" was present on the plane's tray table, which then may have rubbed off onto the allergic individual.

Why is peanut allergy becoming so much more prevalent? The answer is simply that we are eating them more. Peanuts are healthy - if you aren't allergic to them - , and as we adopt healthier lifestyles, we are incorporating them more often in one form or another into our diet.

One question frequently asked of me is whether or not people can outgrow their food allergies. The answer is both yes and no. While I see this frequently with eggs and less commonly with dairy, nut allergies are rarely outgrown.

Food Allergy Reactions

Reactions that may indicate a food allergy are itchy mouth, "fullness" in the throat, shortness of breath, an intense red, itchy rash all over the body, difficulty breathing, and vomiting. In a worst case scenario, as I mentioned above, a food allergy reaction can result in death. Although severe reactions do occur, milder food reactions are more common. Common mild allergic food reactions would be red, itchy skin with hives or eczema (also called atopic dermatitis), and another type of itchy skin rash which can be caused by eggs and many other foods. Some of my patients with mild food allergies have also complained of fatigue or increased nasal irritation.

Diagnosis

When I see someone who has symptoms of a food allergy, I pay close attention to the time which elapsed between the consumption of the suspected food and their reaction. Food allergy reactions usually occur within minutes and sometimes within seconds. So when a person says to me that they ate a certain food yesterday, some skin itching today is probably not due to a food allergy.

Sometimes a diagnosis can be made via trial and error, by eliminating a suspected food. If the skin clears up, the food is reintroduced to see if the skin flares once more. If you are attempting such an elimination diet, stay off the offending foods for at least two weeks and add back each food one at a time every three days.

The best diagnoses, for food allergies, however, are skin testing and RAST (blood) testing. In skin testing, the offending food is lightly scratched into the skin by a disposable plastic "scratcher." If you are allergic, the area gets red and itchy. Its advantages are that the test results are ready within twenty minutes, and that it is cheaper than RAST tests. RAST testing (which measures the presence of certain allergy-inducing antibodies in your bloodstream) is helpful in your family physician's office, where there is no specific allergy specialist who does skin testing. RAST testing is also useful as a confirmation of results from skin testing; in individuals who have a rash on their back which would complicate a skin test; and when only a couple of foods are suspected.

Managing Food Allergies

I always equip my patients with a treatment protocol, in other words a game plan, to follow in case of accidental ingestion, which initially includes an over-the-counter antihistamine, such as diphenhydramine (Benadryl), as well as an epinephrine injection kit, such as an Epi-Pen. I also instruct them to go to a hospital emergency room in case of an attack. In some more severe cases, cases, my treatment protocol includes other medications (like cimetidine or a steroid like prednisone). I also recommend that, if they have a classic food allergy, they should wear a Medical Alert bracelet.

Since some of my patients tell me that allergic foods taste "funny," I sometimes instruct them to leave a suspicious food in their mouth a few seconds before swallowing. The body's natural desire to eliminate the problematic food by vomiting can be lifesaving.

Prevention

Food allergies are most easily developed when we are young. At this stage our intestines are not fully developed and allow large, complex proteins such as peanut protein to cross into the body. Our young bodies recognize such proteins as foreign and form antibodies against them. This may be why there is a great deal of cow's milk allergy in the US, and soy allergy in Japan, where those milks are fed to infants.

To prevent peanut allergy, I feel that babies ideally should not get peanut protein at all during the first two or three years of life. I also advise that pregnant women avoid peanuts, especially if there is a family history of food allergies or strong allergic reactions in general. They should also avoid peanut proteins when breast feeding. It may also be helpful to delay the introduction of some other foods (like other nuts, shellfish, cow's milk, wheat, and soy) into an infant's diet for the first six months of life, but this is a controversial issue.

In the future, it is likely that there will be an oral or injected vaccine for peanuts, which will teach the body to become less allergic.

Is it Food Allergy or Just Sensitivity?

Certain foods are often erroneously blamed for being allergic foods. Rather than being allergic they have naturally occurring histamines within the foods themselves. Examples of foods with natural histamines are

• Wine
• Chocolate
• Strawberries
• Tomatoes

If you are sensitive to one or more of these foods, you might get an itchy rash or a headache after eating them. But if you were tested, your doctor would probably not find any allergic skin or blood results. The exception is wine, some of which is made with preservatives called sulfites and can cause rare but severe allergic reactions. (That's why on wine bottles you see warnings about whether or not the wine contains sulfites.)

Some people say that they are allergic to milk. However, it frequently turns out that their stomach pain, gas, and bloating are caused by an inability to properly digest milk sugar (lactose) due to an enzyme deficiency. The lactose ends up fermenting in the person's intestine, causing discomfort. Eating yogurt or cheeses, drinking lactose-free milk, or taking lactase tablets or acidophilus resolves most of the problem.

Many people believe that milk is mucus producing. I am not convinced that this is true. Others believe that they are allergic to wheat and sugar. Again, this is often undetermined. However, many of these people are indeed sensitive to these foods and do feel better off them. I know parents who believe their children get fewer ear infections and are less irritable off certain foods. I have also encountered a large number of people who believe that they have a yeast allergy and frequently get yeast infections. These people seem to do well on yeast-free diets and off simple sugars (like those found in candies and chocolates).

Always remember that real food allergies can be dangerous, and that potential food allergies should be diagnosed and treated by a physician knowledgeable in this field of medicine.