Chronic Disease

Adults with food allergies tend to have more severe asthma

Food allergies tend to worsen the severity of asthma among children. A new study suggests that allergy to food, especially fish, might also be linked to worse outcomes in adults with asthma. Mount Sinai School of Medicine researchers interviewed 203 adults with persistent asthma being cared for at an inner-city clinic.

The food-allergic group had more asthma-related hospitalizations, emergency department (ED) visits, and use of oral steroids than those without food allergies. Overall, 15 percent of patients reported convincing symptoms of allergy to one food and 7 percent had allergies to more than one food.

Symptoms typically ranged from development of hives, welts, difficulty breathing, and throat itching or closing within an hour of ingesting the offending food. The most prevalent food allergy was shellfish (13 percent of patients), followed by fish (3 percent), peanuts (3 percent), tree nuts (3 percent) seeds (1 percent), milk (1 percent), and eggs (1 percent). Food allergies were not correlated with sensitization to aeroallergens, such as tree pollen or dust.

Several theories link food allergies with asthma. People with asthma who suffer from food allergy may have increased airway hyperreactivity and thus may be more likely to suffer worse asthma. Food allergy may serve as a marker for a skewed host immune response, with a tendency to react with a pro-inflammatory allergic reaction.

Finally, repeated accidental ingestion of the offending foods or chronic inhalation of aerosolized food particles may result in continued immune system activation and resulting inflammation that worsens asthma. Given the low 4 percent prevalence of food allergy among U.S. adults and among those in this study, these findings should be confirmed in larger studies, suggest the researchers. Their work was supported in part by the Agency for Healthcare Research and Quality (HS13312).

More details are in "Food allergy as a risk factor for asthma morbidity in adults," by Stephen H. Berns, M.D., Ethan A. Halm, M.D., M.P.H., Hugh A. Sampson, M.D., and others, in the June 2007 Journal of Asthma 44, pp. 377-381.

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