Not a marketing claim — a randomized trial followed people for four and a half years.
Plenty of products claim to fight aging. Sunscreen is one of the few with a randomized controlled trial behind the specific claim that it slows visible photoaging.
In the Nambour Skin Cancer Prevention Trial, adults were randomized to either daily sunscreen use or discretionary ("use as you like") sunscreen and followed for 4.5 years. The daily-use group showed no detectable increase in photoaging over the period and less skin aging than the discretionary group. A parallel arm testing beta-carotene supplements found no effect on skin aging. [1]
What this means in practice: consistent daily use was the variable that mattered — not an exotic ingredient. Broad-spectrum SPF used regularly is the most evidence-backed "anti-aging" step available.
References
- Sunscreen and Prevention of Skin Aging: A Randomized Trial — Annals of Internal Medicine, 2013