Scientists say cold noses reduce ability to fight virus attacks

November 14, 2005

LONDON, England (CNN) -- British researchers into the common cold say "catching a chill" really does help colds develop -- and are advising to "wrap up warm" to keep viruses at bay.

Mothers and grandmothers have long warned that chilling the surface of the body, through wet clothes, feet and hair, causes common cold symptoms to develop.

But much previous research has dismissed any link between chilling and viral infection as having no scientific basis.

Now researchers in Cardiff, Wales, say they can prove drops in temperature to the body really can cause a cold to develop. (Watch what they did to 'chill' people in the study -- 3:24)

Claire Johnson and Professor Ron Eccles, from Cardiff University's Common Cold Center, recruited 180 volunteers, half of whom they got to immerse their feet in ice and cold water for 20 minutes.

The other 90 in tests during the common cold "season" sat with their feet in an empty bowl.

During the next four or five days, almost a third (29 percent) of the chilled volunteers developed cold symptoms -- compared to just 9 percent in the control group, the scientists said.

Professor Eccles said there was a simple explanation as to why chilly feet could lead to the development of cold virus symptoms.

"When colds are circulating in the community many people are mildly infected but show no symptoms," he said, according to the UK's Press Association.

"If they become chilled this causes a pronounced constriction of the blood vessels in the nose and shuts off the warm blood that supplies the white cells that fight infection.

"The reduced defences in the nose allow the virus to get stronger and common cold symptoms develop.

"Although the chilled subject believes they have `caught a cold' what has in fact happened is that the dormant infection has taken hold."

The researchers, writing in the UK medical journal Family Practice, said that common colds were more prevalent in the winter than the summer, and this could be related to an increased incidence of chilling causing more clinical colds.

But they also suggested that another explanation could be that our noses are colder in the winter.

Professor Eccles added: "A cold nose may be one of the major factors that causes common colds to be seasonal.

"When the cold weather comes we wrap ourselves up in winter coats to keep warm but our nose is directly exposed to the cold air.

"Cooling of the nose slows down clearance of viruses from the nose and slows down the white cells that fight infection.

"Mothers can now be confident in their advice to children to wrap up well in winter."