A diet rich in sodium may potentiate asthma. Epidemiologic evidence for a new hypothesis.

The geographic variation in asthma prevalence and mortality has not been explained adequately. The marked increase in prevalence in communities adopting a more Western lifestyle suggested that some of this variation could be due to changes in sodium intake. The theory was tested using regional data from England and Wales and a strong correlation was found between table salt purchases and asthma mortality in both men and children. Asthma mortality in women was more closely related to prevalence of cigarette smoking. The association was not explained by differences in age, sex or prosperity.