The daily use of sunscreen significantly shows the ageing of skin, and also helps prevent skin cancer, a new study has suggested.

The world-first study of 900 young and middle-aged men and women showed that after four and a half years, those who applied sunscreen most days had no detectable ageing of the skin.

They also had 24 percent less skin ageing than people who used sunscreen only some of the time, if at all.

The study was led by Queensland Australian of the Year, Queensland Institute of Medical Research`s Professor Adele Green, in collaboration with investigators at the University of Queensland`s School of Population Health.

"This has been one of those beauty tips you often hear quoted, but for the first time we can back it with science: protecting yourself from skin cancer by using sunscreen regularly has the added bonus of keeping you looking younger," Professor Green said.

"And the study has shown that up to middle age, it`s not too late to make a difference."

The research - part of QIMR`s long-running Nambour Skin Cancer Prevention Trial - involved half of the participants regularly using SPF15+ sunscreen on their face, arms and hands and the other half using sunscreen in their usual way, if at all.

Silicone impressions, or moulds, were taken from the backs of all participants` hands at the start and end of the trial to grade the damage over the four and a half years of the study.

The participants were all aged under 55, to ensure that photo-ageing, rather than chronological ageing, was the major factor in skin changes.

"And of course, along with seeking shade and wearing clothing cover, sunscreen is a mainstay of sun protection. It prevents sunburn in the short-term and skin cancer in the long-term,` Professor Green said.

The study also tested the theory that beta-carotene supplements can prevent skin ageing.

"Our findings suggest that beta-carotene supplements do not influence skin ageing, although we can`t rule out the possibility of a small difference for better or worse. There would need to be further study into beta-carotene to rule out benefit or harm," Professor Green said.

The study was recently published in the Annals of Internal Medicine.