Most asthmatics have several triggers than aggravate their symptoms. Some asthma triggers are difficult if not impossible to control such as the air temperature, pollen levels, dust, and exposure to viral upper respiratory infections. One potential asthma trigger that can more easily be controlled is sodium chloride, or ordinary table salt. It has been noted that asthma incidence is rising rapidly, particularly in more westernized countries. As the Western diet has changed during the last few decades, its influence upon the rise of asthma symptoms has been particularly scrutinized. Although the minimum daily requirement for sodium is about 500 mg and the maximum daily recommended salt intake is 2400 mg, the average individual in western countries is between 7000 and 10,000 mg. Sodium has long been implicated in cardiovascular disease and hypertension, but more recently has been found to have a possible relationship with asthma.

Researchers first proposed a link to dietary salt and asthma over eighty years ago. Although it was noted that there was a connection between high salt intake and an increase in asthma symptoms and vice versa, the exact nature of the relationship was not understood. It is hypothesized that high salt diets may have an inflammatory effect and increase bronchial hyperreactivity. Many other studies have been done since that time with varying results, but most seem to indicate that following a low sodium diet (about 2000 mg per day) for about 2-5 weeks appears to improve lung function in asthmatic adults. Some studies have also shown that low salt diets decrease bronchoconstriction during exercise, which may be particularly important for those with exercise-induced asthma. Long-term followup studies still need to be done, as well as research into whether low sodium diets can reduce the incidence and overall severity of asthma.

Although a high salt intake does not cause asthma and a low-salt diet cannot cure asthma, it still may be a worthwhile effort for asthmatics to try and see if it will improve their lungs as well as their heart!