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Systemic contact dermatitis tracked to allergens in foods.

PORTLAND, ORE. -- A broad and diverse group of foods contains nickel, and consumption of these foods has the potential to exacerbate allergic contact dermatitis, particularly in patients receiving more than one exposure per day, Dr. David E. Cohen said at the annual meeting of the Pacific Northwest Dermatological Society.

It's no surprise that items such as jewelry or jeans snaps might be a problem in patients with allergic contact dermatitis, since these are well-known sources of nickel that come into contact with the skin.

But edamame? It's true. The green soybean snacks contain enough naturally occurring nickel--nearly 0.9 mg per serving--to have the potential of leading to systemic contact dermitis in up to 10% of nickel-sensitive patients, said Dr. Cohen, director of allergic, occupational, and contact dermatitis at New York University.

The normal dietary intake of nickel ranges from 0.02 mg to 0.48 mg/day, and the Food and Drug Administration has set 50 mcg as the tolerable upper intake level recommended in nickel allergic adults. Still, certain foods, including soybeans, cashews, lentils, figs, and raspberries, have high nickel content and could cause a flare in allergic patients. (See chart.)

Sometimes the allergen source in foods is even more subtle, noted Dr. Cohen, who conducted a study of three types of tomatoes to identify natural fragrances that might explain their proclivity to produce systemic contact allergy reactions in certain patients (Dermatitis 2005;16:91-100).

Several potent constituents of the well-known allergen balsam of Peru, including cinnamic acid, and coniferyl alcohol were detected in various quantities in beefsteak, cherry, and plum tomatoes, he said.

"These reactions can look quite banal and don't have any particular distribution to clue in the evaluating [physician]," Dr. Cohen said during an interview following the meeting.

When the cause of the flares is uncertain and seems to point to foods, Dr. Cohen recommends eliminating all foods containing the suspected allergen for 3 weeks. "Then [tell them to] eat a ton of whatever they miss most," he said. If a flare ensues, the culprit food may be unmasked.


Los Angeles Bureau
Nickel Content of Foods

Over 0.05 mg Cashews (18 nuts)
 Cocoa (1 tbsp)
 Figs (5)
 Lentils (1/2 cup, cooked)
 Raspberries (30)
 Soybeans (boiled, 1 cup)
0.02-0.05 mg Asparagus (6 spears)
 Lobster (3 oz)
 Oat flakes (2/3 cup)
 Peas (frozen, 1/2 cup)
 Pistachios (47)
 Vegetables (canned, 1/2 cup)
Under 0.02 mg Apple (1 medium)
 Bread (wheat, 1 slice)
 Carrots (8 sticks)
 Cheese (1.5 oz)
 Cornflakes (1 cup)
 Mineral water (8 oz)
 Mushrooms (raw, 1/2 cup)
 Poultry (3.5 oz)
 Strawberries (7 medium)
 Yogurt (1 cup)

Source: Dr. Cohen
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Title Annotation:Dermatology
Author:Bates, Betsy
Publication:Internal Medicine News
Geographic Code:1USA
Date:Sep 1, 2006
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