March 5, 2008

Dr. Collins: Watch Out for Exercise-Induced Food Allergies

We have all heard that statement, "You are what you eat." For some athletes, it should be "You are as fast as you eat."

Food allergies are often difficult to investigate and identify. In athletes, there can be an even more complex syndrome where they tolerate a particular food in their daily life, but have an allergic reaction if they consume that food in conjunction with intense exercise.

In many cases, since the problem only comes on when the offending food is taken close to the activity, it can be very difficult for the athlete to recognize the connection. Still, they can certainly feel the effects with rashes, itchiness, wheezing and shortness of breath.

In some cases, the effect can be so profound that the athlete passes out.

For most of those that suffer from exercise-induced food allergies, the effect is subtle but still can affect their performance significantly. The intent of this article is for you to think about this when your athletic performance is perhaps not what you expected, say on a run like Robie, and you are looking for reasons. It is a relatively rare problem, but it can be a factor if your stamina was not what you expected.

For most people an exercise-related allergic reaction to food is usually uncomfortable but not life threatening. In exercise-related food allergy, the physical trauma of food in the intestinal tract being repetitively jostled around is suspected to be part of the problem. As we age, we seem to overcome many food allergies by developing some sort of intestinal resistance to the intake of the offending allergens.

When you are carrying a food you would be otherwise allergic to and do exercise, it seems those defenses may be broken down on a microscopic level. This is certainly not proven, but there is a theory out there that supports the idea.

The result can be a variety of symptoms that one sees with food allergies. These include:

_ Tingling in the mouth

_ Hives, itching, or eczema

_ Swelling of the lips, face, tongue, throat, or other parts of the body

_ Wheezing, nasal congestion or a feeling of "tightness" in the chest.

_ Dizziness, lightheadedness or fainting

If the reaction is more severe, you could develop signs of anaphylaxis, which could be life threatening. The symptoms of this include:

_ Constriction of airways with a feeling of a lump in the throat making it difficulty to breathe

_ Severe wheezing

_ Rapid pulse

_ A severe drop in blood pressure with fainting or shock

The reaction is often associated with the release of histamine, which can cause the runny nose, itchy eyes, rashes, hives, nausea, diarrhea, difficulty breathing and even anaphylactic shock.

Food intolerance can often appear to be food allergy since it can cause nausea, vomiting, cramping or diarrhea. However, it does not cause the lung constriction and risk that food allergies do. It can be difficult to tell the difference without testing since food intolerance allows you to eat a small amount of the offending food without significant problems.

With a true food allergy, even a small amount can cause an allergic reaction. With exercise induced food allergy, it seems that this small exposure comes when the defenses your body has built up in the intestines are overcome. It is this trauma that breaks the barrier to the blood system and that allows the otherwise tolerated foods to cause problems.

If you are an athlete whose performance varies from time to time without any specific cause, you might consider exercise-induced allergy as a possibility.

The place to start if you suspect an allergic reaction to a food is to look at specifically what you eat and how long before you exercise or race. In other words, keep a food diary with times of eating and workouts. Keep a specific description of your symptoms for your doctor and document right down to the brand which foods you eat and when relative to your workouts. Ask your parents and other family members if they have any food allergy problems. Once you get a list of what you are putting in your stomach, consider doing an "elimination diet." This means you keep a specific food out of your diet and then record how you react. This can give your doctor some useful data.

As you move ahead on this, make sure you start with a visit to your doctor to make sure it is not a physical problem other than allergy that is causing your troubles.

Reactions to different foods can be assessed, although the results are often not 100 percent certain. Still, given enough information and testing, your doctor can often arrive at the cause. This will result in a list of foods that you should not eat around the time you will be exercising or racing. With exercise-induced allergies, the good news is that as long as you are not going to be running within four to six hours, you can enjoy just about any food.


The most common food allergies for adults include:

_ Eggs

_ Peanuts

_ Fish

_ Shellfish such as shrimp or crab

_ Tree nuts such as walnuts or pecans

Children also can have allergic problems triggered by cow's milk, wheat or soybeans.


There is some evidence that there can be cross-reactivity with certain pollens and fruits and vegetables.

If you are allergic to Birch pollen, you may react to:

_ Apples

_ Peaches

_ Plums

_ Nectarines

_ Cherries

_ Carrots

_ Celery

_ Raw potatoes

_ Almonds

If you are allergic to Ragweed Pollen, you may react to:

_ Melons

_ Bananas

_ Tomatoes

If you are allergic to grasses, you may react to:

_ Melons

_ Kiwis

_ Tomatoes

If you are allergic to Mugwort pollen, you may react to:

_ Carrots

_ Celery

_ Spices


(Paul Collins, M.D. is an orthopedic surgeon specializing in sports medicine at Orthopedic Health Care in Boise, Idaho. Collins is an avid participant in many outdoor activities. Please send your sports medicine questions to [email protected] or at The Idaho Statesman, P.O. Box 40, Boise, ID 83707.)



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