New evidence suggests that soy allergies may be linked to allergic asthma symptoms in people who work at soy processing plants.

Asthma is classified as either allergic or non-allergic. Both conditions cause airway obstruction and inflammation that is partly reversible by medication. They also produce the same symptoms. The main difference, however, is their cause. Inhaled allergens like dust mites, mold spores, pollen and pet dander may trigger allergic asthma. It is the most common form of asthma, affecting more than 50% of patients with asthma.

The study included 281 workers at a Tennessee-based soy processing plant. Nine percent of the workers were diagnosed with asthma, which is significantly higher than average for American adults. Twenty-nine percent reported symptoms of wheezing in the past year.

According to blood tests, 21 percent of workers had soy-specific immunoglobulin E (IgE) antibodies, compared to four percent in a control group of 50 healthcare workers. IgE triggers allergic reactions against foreign substances like pollen. The researchers found that people with soy-specific IgE were three times more likely to have asthma-like symptoms than those who did not have the antibodies.

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1. Cummings KJ, Gaughan DM, Kullman GJ, et al. Adverse respiratory outcomes associated with occupational exposures at a soy processing plant. Eur Respir J. 2010 Apr 22. View Abstract
2. Natural Standard: The Authority on Integrative Medicine. www.naturalstandard.com