Salt Intake,Asthma, and Exercise-Induced Bronchoconstriction: A Review

Abstract

Despite the heterogeneous treatment options for patients with asthma, there remains a substantial burden of unaddressed disease, even with optimal treatment. Epidemiological studies indicate that patients frequently resort to complimentary and alternative therapies when being treated for asthma and other chronic health conditions. Changes in diet associated with the development of a more affluent lifestyle is one of the environmental factors considered to contribute to the increased prevalence of asthma in the past few decades. Dietary sodium in particular has been considered to be a dietary constituent implicated in this phenomenon. This article reviews the studies conducted that have questioned whether reducing dietary salt intake potentially improves pulmonary function and airway hyper-responsiveness in asthmatics, as well as studies evaluating dietary salt intake on the severity of exercise-induced bronchoconstriction (EIB). The data presented supporting dietary salt restriction for reducing airway hyper-responsiveness in asthmatics is encouraging, though not clinically convincing. Studies conducted previously have been limited for a variety of reasons, including limitations related to the experiment and populations studied. However, in studies that evaluated the severity of EIB in asthmatic individuals and involved altered dietary salt intake, data have been more convincing. A low-sodium diet maintained for 1 to 2 weeks decreases bronchoconstriction in response to exercise in individuals with asthma. There are no data regarding the longer-term effects of a low-sodium diet on either the prevalence or severity of asthma or on EIB. As a low-sodium diet has other beneficial health effects, it can be considered a therapeutic option for adults with asthma, although it should be considered as an adjunctive intervention to supplement optimal pharmacotherapy, and not as an alternative.