Cystic fibrosis sufferers prone to damaging infections may be able to fight them more effectively with a simple sugar inhaler.

Approximately 7,500 people in the UK have the inherited condition, in which the lungs produce far too much mucus, clogging the airways and making it hard to breathe.

In addition, the mucus is a perfect breeding ground for bacteria, and patients are vulnerable to illnesses which can cause permanent damage.

The average life expectancy for a cystic fibrosis patient is only 30 years, and most constantly take antibiotics to control bacteria, in addition to regular physiotherapy to loosen and disperse mucus from the lungs.

The research team from the University of Iowa noticed that the sugar, called xylitol, when found in some brands of chewing gum could help children with middle ear infections.

The lungs have their own anti-bacterial action, produced by a liquid which overlays the cells lining the lung.

In cystic fibrosis, this mechanism is far less effective, because the level of salt concentration in the airway surface liquid is far too high.

Xylitol lowers the salt concentration - enhancing the body's own bacteria-killing activity.

Nasal bacteria

In addition, bacteria cannot feed on xylitol, making it ideal for the purpose.

The anti-bacterial qualities of xylitol were tested by the University of Iowa team, who sprayed it into the noses of a dozen volunteers, and then assessed the level of bacteria.

The sugar spray significantly reduced the number of nasal bacteria detected.

Dr Michael Welsh, from the Howard Hughes Medical Institute, said: "The hope is that this could help prevent, or at least delay, the onset of infection in lungs of people with cystic fibrosis, and people who don't have cystic fibrosis but are prone to lung infections."

A spokesman for the Cystic Fibrosis Trust, a UK charity said that anything that reduced the need for constant antibiotics and physiotherapy would be welcome.

He said: "If you don't get rid of infections quickly, it can cause permanent damage, which can be cumulative.

"One of our big hopes for the future is gene therapy, but this, if it works, might help in the meantime."

The research was published in the Proceedings of the National Academy of Sciences.