The research, which was funded by the National Health and Medical Research Council of Australia, focused on a group of 903 randomly chosen adults that were all aged under 55.
The purpose of the study was to determine to what extent regular use of sunscreen slowed skin aging measured by degree of photoaging, compared with discretionary use of sunscreen in combination with β-carotene antioxidant supplements and a placebo.
Four groups divided into discretionary and daily sunscreen use
The study was assigned to 4 groups: daily use of broad-spectrum sunscreen and 30 mg of β-carotene, daily use of sunscreen and placebo, discretionary use of sunscreen and 30 mg of β-carotene, and discretionary use of sunscreen and placebo.
The groups that used sunscreen daily were asked to apply SPF 15+ to their head, neck, arms and hands each morning and after bathing, as well as during sun exposure and after heavy sweating.
The assessments were made over a four and a half year period using microscopic impressions of the subjects hands to determine how much damage was visible.
No detectable signs of aging for daily sunscreen users
The images showed that the group using sunscreen on a daily basis showed no detectable signs of skin aging, while skin aging from the baseline to the end of the trial was 24 percent less in the daily sunscreen group, compared to the discretionary group.
Meanwhile, individuals who took the β-carotene supplement showed no overall effect on skin aging, although there were some contrasting results in sub groups that had contrasting ranges of severity in aging at the baseline.
The results underline the continued blurring between the anti-aging category and the sunscreen category, lending further impetus to daily use moisturizers that combine with sunscreens, as well as sun care products that make anti-aging claims on the labels.
*The full report is titled “Sunscreen and Prevention of Skin Aging. A Randomized Trial,” and was published in the 4 June 2013 issue of Annals of Internal Medicine. The authors are M.C.B. Hughes, G.M. Williams, P. Baker, and A.C. Green.