[Bronchial asthma and kitchen salt]

Abstract

Epidemiological studies show considerable geographic differences in asthma prevalence and mortality. The regions with high prevalence and mortality are countries with Western-type culture and a high degree of technological progress. They differ from less technically developed countries in a number of ways, including their higher salt intake. Air pollution is often given as the cause of the high prevalence of asthma in the industrialized countries. Against this, it must be pointed out that in the urban agglomerations of the developing countries and in rural areas where heating is by means of open fireplaces (indoor pollution), there is also considerable air pollution. Migration studies from New Zealand and South Africa, where asthma prevalence increases parallel to salt intake, provide evidence that other factors arising from westernization and urbanization play a role. In the industrialized countries England and USA there is also a clear connection between salt intake and asthma: the greater the salt consumption, the higher the asthma prevalence and mortality. On the basis of these observations, the following questions were investigated: (1.) Does salt loading worsen the clinical and functional findings in asthmatics? (2.) Is the sodium or the chloride in salt the more important? To answer these questions, the effect of salt loading (+6.1 +/- 2.8 g NaCl/d = 105 +/- 48 mmol Na), salt restriction, and loading with sodium citrate in equimolar concentrations (+140 +/- 40 ml Shohl's solution = 120 +/- 34 mmol Na) was investigated in 14 asthmatics in a controlled crossover study. Statistical analysis showed that salt intake worsened symptoms (p = 0.06) and increased the use of inhaled steroids (p less than or equal to 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)