Daily use of sunscreen can slow skin aging associated with middle age, according to an Annals of Internal Medicine study.

Researchers in Australia randomized some 900 adults younger than 55 (mean age, 39) to four treatments: daily broad-spectrum sunscreen (SPF 15+) plus beta carotene supplementation, daily sunscreen plus placebo, discretionary sunscreen plus beta carotene, or discretionary sunscreen plus placebo.

After 4.5 years’ follow-up, only daily sunscreen users showed no increase in photoaging. Compared with discretionary sunscreen users, daily users were 24% less likely to have increased photoaging. Beta carotene use did not appear to have a protective effect.

The authors point out that small changes in photoaging correlate with increased risk for skin cancer. They write: “A reduction in the highly prevalent aging changes among middle-aged adults by regular application of sunscreen will therefore be associated with cosmetic benefit … and reduced risk for skin cancer.”