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Touched by an Allergy

New study shows contact dermatitis may be linked to food allergy

WEDNESDAY, Oct. 17, 2001 (HealthDayNews) -- Polishing off a bowl of chili, having a dollop of vanilla ice cream and chasing them down with a bottle of cola may not only give you a stomach ache, they may give you contact dermatitis, says a controversial new study.

Contrary to traditional medical thinking, new research shows that the common, itchy and irritating skin allergy normally triggered by something you touch could just as easily be caused by something you eat.

While a number of European studies have suggested this could be the case, the latest finding, published in the journal Dermatology, is among the first U.S. studies to reach this conclusion.

"We found that not only can certain foods trigger contact dermatitis, we also learned that eliminating the offending foods helped the dermatitis to clear," says Dr. Joseph Fowler, lead study author and professor of dermatology University of Louisville, in Kentucky.

The finding is important because contact dermatitis can be a puzzling condition that is hard to treat, particularly when the cause can't be pinned down, says Fowler. The idea that it may not be the result of something patients touch but rather something they eat gives doctors a new treatment avenue to pursue.

Not everyone, however, agrees with that logic.

"I don't buy it, unless we are saying these foods come in direct contact with the skin," says Dr. Sheryl Miller, assistant professor of dermatology at Weill Cornell Medical College, in New York City.

Contact dermatitis is by definition contact, so it means touch, says Miller. "I can see where putting the peel of an orange on your lip or mouth may cause an irritation, because you are getting the contact, but I don't see eating that orange peel as having the same result."

Miller says enzymes in the mouth and stomach usually will change foods so that irritants that cause the skin reaction are no longer present. She says this seems particularly true of the foods included in this study. All were related to a single substance called balsam of Peru (BOP).

Derived from the tree Myroxylon Pereira, the extract contains dozens of individual compounds that show up in a wide variety of foods and other products.

"Items as diverse as tomatoes, chocolate, citrus fruits, cola and a variety of spices, including vanilla, all contain components of balsam of Peru " says Fowler. Research shows other foods that contain BOP components include cinnamon, cloves, curry, chutney, spiced herring, pickled vegetables -- even certain cough medicines, toothpastes and mouth washes.

Fowler says because elements of BOP can be found in so many foods, it becomes an ideal compound for allergy testing. With a positive patch test to a BOP compound (indicating an allergic reaction) doctors can generate a long list of foods that could cause contact dermatitis, including candy, cookies, condiments, chili, ice cream, soups, even marmalade.

"Once you know possible causes, it's easy to eliminate those foods and then introduce them back into the diet one at a time until you find out which one is causing the allergic reaction," says Fowler.

And that's precisely how the study was conducted.

It began with 71 patients all diagnosed with contact dermatitis, all of whom were tested and found to be allergic to BOP.

Based on the severity of symptoms, the people were divided into three groups. The first two groups, identified as A and B, totaled 45 patients and had the strongest skin reaction to BOP.

They were placed on an elimination diet, restricting all foods related to BOP for three to six weeks. The third group of 36 patients, identified as group C, followed their normal diet.

The result: Of the 45 patients in groups A and B, 21 (about 47 percent) reported either complete or marked improvement of their dermatitis during the elimination phase of the diet. The third group had no change in symptoms.

Miller finds the study interesting, but doesn't see its significance to contact dermatitis.

"Contact is contact. The name implies that you have to actually touch something to get this reaction; if touching is not involved, then I question the initial diagnosis," says Miller.

While rashes can occur in conjunction with a systemic food allergy, she says they are not considered contact dermatitis and do not have the same symptoms.

Fowler says many doctors don't know that contact dermatitis can be caused or at least aggravated by an allergen you eat as well as those you touch.

"Judging by the fact that the dermatitis got better when certain foods were eliminated from the diet indicates there is a strong likelihood of a systemic connection," says Fowler.

What To Do

For more information on contact dermatitis, visit The American College of Dermatology or this Centers for Disease Control and Prevention site.

For more information on balsam of Peru allergies, click here.

SOURCES: Interviews with Joseph Fowler, M.D., associate professor of dermatology, University of Louisville, Kentucky, and Sheryl Miller, M.D., assistant professor of dermatology, Weill Cornell Medical College; September 2001 Dermatology
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