How anti-aging cosmetic ingredients compare on evidence quality

This review gathered 32 studies covering 1,236 patients and graded the evidence behind common anti-aging skincare ingredients using a standard scale. Retinol and vitamin C received the top grade. Bakuchiol received a C. A grade of C does not mean an ingredient does not work — it means the studies supporting it are smaller, less rigorous, or fewer than the studies supporting the top-graded ingredients. It is a useful reference point when marketing presents two ingredients as equivalent choices.