Asthma is a syndrome that may have many causes resulting in airway inflammation and hyperresponsiveness. The search for the causes of asthma has led to the investigation of genetic, atopic, viral, and nutritional factors. For the last 2 decades, a number of studies have linked particular nutrients to asthma. The studies have examined both the suboptimal status of particular nutrients as causes of asthma and supplements of specific nutrients as therapy for asthma. We reviewed and analyzed data from these studies to determine the role of nutritional therapy in the management of asthma. The studies on food allergies reveal that IgE-mediated reactions to food are a minor cause of respiratory symptoms, affecting more children than adults. Currently, there are no available data to support the use of nutritional supplements in the treatment of chronic asthma.