MedWire News: A low-salt diet can help reduce blood pressure and improve cardiovascular health, but it does not appear to reduce respiratory symptoms in people with asthma, researchers have found.

Some studies have suggested that asthma patients with a low-salt diet have fewer respiratory symptoms and better lung function than those with a high-salt diet, but others have found no such association, explain Dr Zara Pogson, from the University of Nottingham, and colleagues.

To investigate further, the team studied 220 people with asthma who were aged between 18 and 65 years.

Eighty-nine of the participants were assigned to a diet containing low levels of sodium - the component of salt linked to health problems - for 6 weeks, while the remaining patients were assigned to a diet containing medium levels of sodium.

All the participants continued to take their usual asthma medications over the course of the study.

At the end of the 6-week study period, the researchers found no significant differences between the two groups regarding lung function, asthma symptoms and the use of asthma medications.

The team also found no significant differences in quality of life between the two groups at the end of the study period.

Writing in the American Journal of Respiratory and Critical Care Medicine, Dr Pogson and team conclude: "Our data suggest that despite the clear benefit of a low sodium diet on cardiovascular risk factors, there is no therapeutic benefit in the use of a low sodium diet... on asthma control."