Objective. The role of salt intake as a risk factor for asthma, bronchial hyperresponsiveness, and other bronchial symptoms has been addressed in a number of studies. Collectively, these studies indicate an increased risk of bronchial symptoms with high consumption of salt, but the issue remains controversial. We tested prospectively the hypothesis that salt intake would be an independent risk factor for chronic bronchitis (CB). Design. A 10-year prospective study of 2,183 men aged 46 to 65 years without any relevant lung symptoms at baseline. Main Outcome. Chronic bronchitis. Results. During the 10-year followup, the overall incidence of CB was 7.1% among men without any relevant lung symptoms at baseline. In a multiple logistic regression analysis, controlling for age, smoking habits, occupational dust exposure, alcohol use, and social class, the odds ratio associated with self-assessed high salt preference (reported by 24%) was 1.6 (1.1–2.4). Interpretation. The results suggest that salt restriction may prevent chronic bronchitis. 1. Background The role of salt intake as a risk factor for asthma, bronchial hyperresponsiveness, and other bronchial symptoms has been addressed in a number of studies as reviewed by Mickleborough and Fogarty [1]. Collectively, these studies indicate an increased risk of bronchial symptoms with high consumption of salt. To our knowledge, no prospective epidemiological studies have specifically focused on dietary salt intake as a risk factor for chronic bronchitis (CB). Recently, in a 16-year followup from the Copenhagen Male Study (CMS) using a baseline established in 1985-86 we showed that CB was a significant risk factor for lung cancer mortality. At baseline, self-assessed high salt intake was associated with a twofold higher prevalence of chronic bronchitis (CB) [2]. Accordingly, since in the CMS we have access to data making a prospective analysis possible, we decided to study if salt intake would be an independent predictor of chronic bronchitis. Furthermore, the available data would provide the opportunity to carry out an analysis, which may be considered a “natural experiment”. In short, the CMS is a closed cohort study of 5,249 gainfully employed men, which was established in 1970-71, at the time the men were 40 to 59 years old with a median age of 48. One year later, all men were invited to participate in a reexamination using a similar method. In 1976, a postal questionnaire was carried out which was returned by more than 4,000 of the men, and in 1985-86 all survivors were invited to participate in a more
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