When Peanuts Are Poison

Is shellfish suddenly banned from your diet because you’ve become allergic? Does peanut butter pose a threat to your grandchild’s life?

You’re hardly alone. For unknown reasons, food allergies climbed 18 percent among U.S. children between 1997 and 2007; 3 million kids are now affected, according to the National Center for Health Statistics. About 9 million adults have food allergies, and sudden food allergies in adults have become more common, says Fred Hsieh, MD, a Staff Physician in allergy and immunology at Cleveland Clinic’s Respiratory Institute.

“Whether it’s due to food processing or some additives in the food,” says Dr. Hsieh, “no one has the answer.”

Food allergies can be life-threatening, causing about 30,000 severe allergic reactions and 150 deaths every year in the United States, according to the National Institute of Allergy and Infectious Diseases.

The good news? Allergies to cow’s milk and eggs are likely to disappear with age, Dr. Hsieh says. Close to 80 percent of kids outgrow milk allergies by age 16, according to a 2007 study in the Journal of Allergy and Clinical Immunology.

Because there’s no cure for allergies that aren’t outgrown, treatment involves managing the condition by identifying problem foods and avoiding them. Patients at risk of anaphylaxis can also carry an injectable prescription dose of the hormone epinephrine to stop a reaction and open the airways.

A promising experimental treatment known as desensitization suggests that some patients may become tolerant enough of allergy-provoking foods to avoid a serious reaction if they’re exposed. They may even be able to eat the food for pleasure.

Two studies in the August 2009 Journal of Allergy and Clinical Immunology showed the potential of this approach: Children in the studies who gradually built up tolerance to peanut powder over six months were able to eat up to 15 peanuts in one sitting without a reaction, according to co-author Wesley Burks, MD, Chief of Pediatric Allergy and Immunology at Duke University School of Medicine. Three years after beginning the treatment, one-third of the children were eating peanuts without any symptoms. After five years, three-quarters of the children were able to do so, according to updated findings presented at the 2010 annual meeting of the American Academy of Allergy, Asthma & Immunology. The technique was tried in a separate study using egg-white powder for kids with egg allergies. One year into daily treatment the children were able to tolerate up to two eggs at a time, says Dr. Burks. Ninety percent of kids in a smaller, earlier version of that study that began five years ago are now able to eat as many eggs as they want.

Desensitization isn’t available outside a research setting, however, and shouldn’t be tried at home, Dr. Hsieh cautions.

For women who are pregnant or planning to have children, the best weapon for reducing a child’s risk of developing a food allergy is breastfeeding, according to the American Academy of Pediatrics. “The only thing you can reliably say is to breastfeed for the first six months of life, regardless of whether the mother has a food allergy or if the child has early signs of eczema or other food allergy,” Dr. Hsieh says.

But don’t believe rumors that avoiding allergenic foods, such as peanuts or shellfish, during pregnancy or breastfeeding can keep a child allergy-free, he adds. Feeding children probiotics or keeping common food allergens out of a child’s diet also haven’t been proved to prevent food allergies from developing.

Dr. Hsieh says there’s reason to be hopeful. “Increasing public awareness — and growing funding for food-allergy research — make it possible that new treatments will be available in the future,” he says.

Better food labeling that indicates when foods are allergenic can help, too. See a nutritionist for extra guidance and tips. “Patients can enjoy eating,” Dr. Hsieh says. “They just need to be cautious.”