London, March 4
High-salt diet is bad for health, say numerous studies, but a significant research now reveals that dietary salt could have a biological advantage -- defending the body against invading bacteria.

They found that a high-salt diet increased sodium accumulation in the skin of mice, thereby boosting their immune response to a skin-infecting parasite.

The findings suggest that dietary salt could have therapeutic potential to promote host defence against microbial infections.

Till now, high-salt is clearly known to be detrimental for cardiovascular diseases and stroke.

"Our study challenges this one-sided view and suggests that increasing salt accumulation at the site of infections might be an ancient strategy to ward off infections, long before antibiotics were invented," explained first study author Jonathan Jantsch, microbiologist at Universitatsklinikum Regensburg and Universitat Regensburg in Germany.

A clue to this mystery came when the team noticed an unusually high amount of sodium in the infected skin of mice that had been bitten by cage mates.

Intrigued by this observation, they examined the link between infection and salt accumulation in the skin.

The team found that infected areas in patients with bacterial skin infections also showed remarkably high salt accumulation.

Moreover, experiments in mice showed that a high-salt diet boosted the activity of immune cells called macrophages, thereby promoting the healing of feet that were infected with a protozoan parasite.

The researchers, however, urge caution over the potential health benefits of a high-salt diet.

"Due to the overwhelming clinical studies demonstrating that high dietary salt is detrimental to hypertension and cardiovascular diseases, we feel that at present our data does not justify recommendations on high dietary salt in the general population," Jantsch commented.

"Nevertheless, in situations where endogenous accumulation of salt to sites of infection is insufficient, supplementation of salt might be a therapeutic option," he emphasised.

Moving forward, the researchers will examine how salt accumulates in the skin and triggers immune responses and why salt accumulates in the skin of ageing adults.

"We also think that local application of high-salt-containing wound dressings and the development of other salt-boosting antimicrobial therapies might bear therapeutic potential," the authors concluded.

The paper appeared in the journal Cell Press.