Nottingham University researchers found no evidence that cutting back on salt helps patients with their symptoms.
Nearly 200 subjects completed a randomised trial, which compared the effect of changes in bronchial reactivity on asthma patients who followed a strict low-sodium diet.
Subjects received either sodium supplements equal to 80mmol a day or a placebo for six weeks. Researchers detected no differences between the groups.
Lead author Zara Pogson, clinical research fellow at the University, said: ‘We were disappointed that a simple measure, such as a decrease in sodium intake, does not result in improvements in asthma control.
‘We therefore cannot advise people with asthma to alter their sodium intake to improve control of their asthma, despite the fact that a low-sodium diet improves cardiovascular risk factors,’ she said.
American Journal of Respiratory and Critical Care Medicine (2008) 178: 132-138