It looks like less collagen means more wrinkle formation

Dr Akimichi Morita, Nagoya City University Medical School

They found that cells exposed to smoke produced far more of the enzyme responsible for breaking down skin.

Skin stays healthy and young-looking because it has the ability to constantly regenerate itself.

This process depends on a subtle balance between the ability to break down old skin, and to create fresh replacement tissue.

The body breaks down old skin with enzymes called matrix metalloproteinases (MMPs).

These enzymes chop up the fibres that form collagen - the tissue that makes up about 80% of normal skin.

New Scientist magazine reports that the researchers tested the impact of cigarette smoke by pumping it through a saline solution and adding the resulting mixture to collagen-producing skin cells.

They found that cells exposed to smoke produced far more MMP than normal skin cells.

Poet WH Auden was a heavy smoker

The researchers also found that smoke caused a drop in the production of fresh collagen by up to 40%.

Lead researcher Dr Akimichi Morita said the combined effect is probably what causes premature skin ageing in smokers.

His team found the effect was more pronounced when cells were exposed to more concentrated cigarette smoke.

Dr Morita said: "This suggests the amount of collagen is important for skin ageing.

"It looks like less collagen means more wrinkle formation."

Dr Morita plans to confirm his findings by testing skin samples from smokers and non-smokers of various ages to see if the smoking has the same effect on collagen.

"So far we have only done this in the lab. We don't know exactly what happens in the body yet - that might take some time."

It might have more of an impact on young people who are often more concerned with their appearance than they are about their internal organs

Amanda Sandford, Action on Smoking and Health (ASH)

Dr Lawrence Parish, director of the Centre for International Dermatology at Thomas Jefferson University Hospital in Philadelphia said the study confirmed what has long expected.

"Tobacco smoke is injurious to skin."

Amanda Sandford, of the anti-smoking charity Action on Smoking and Health (ASH), said the research might help to make young people think twice about taking up the habit.

She said: "This will be useful in health education campaigns, explaining to people the effect smoking has on the skin.

"In particular, it might have more of an impact on young people who are often more concerned with their appearance than they are about their internal organs."