Daily sunscreen appears better than beta-carotene for preventing skin aging

Daily sunscreen use prevents skin aging better than discretionary use or beta-carotene supplementation, according to a new study.

Researchers in Australia performed a randomized, controlled, community-based trial to determine whether regular sunscreen use compared with discretionary use or beta-carotene supplements compared with placebo helped slow skin aging. Patients were randomly assigned to use broad-spectrum sunscreen and take 30 mg of beta-carotene daily, use sunscreen and take placebo, use discretionary sunscreen and take 30 mg of beta-carotene, or use discretionary sunscreen and take placebo. The main outcome measure was change in microtopography between 1992 and 1996 in the sunscreen and beta-carotene groups compared with controls. Skin surface replicas from the back of the left hand were taken by using silicone-based impression materials and graded replicas by using the Beagley and Gibson scale. Grades increase from 1 (undamaged skin with fine lines evenly spaced in a two-directional network) to 6 (increasing severity of changes characterized by surface flattening, deepening of horizontal lines and loss of vertical lines).

Results appear in the June 4 Annals of Internal Medicine.

The study included 903 adults younger than 55 years of age who were randomly chosen from a community register. Patients randomly assigned to daily sunscreen use were directed to apply it to their heads, necks, arms and hands every morning and to reapply after heavily sweating, bathing or spending extended time outdoors. After four and a half years, patients who used sunscreen daily had no detectable increase in skin aging. From baseline to the end of the trial, those who used sunscreen daily exhibited 24% less skin aging than those who used it on a discretionary basis (relative odds, 0.76; 95% CI, 0.59 to 0.98). Beta-carotene supplementation appeared to have no overall effect on skin aging.

The authors acknowledged that the study was missing some outcomes data and that it had only modest power to detect moderate treatment effects, among other limitations. However, they concluded that regular sunscreen use appears to slow skin aging in healthy, middle-aged men and women. Although beta-carotene did not have a measurable effect on skin aging, the authors noted that further study is needed to completely exclude the potential for benefit or harm.