Katiyar, S. K., Afaq, F., Perez, A., & Mukhtar, H. (2001). Green tea polyphenol (-)-epigallocatechin-3-gallate treatment of human skin inhibits ultraviolet radiation-induced oxidative stress. Carcinogenesis, 22(2), 287-294. https://doi.org/10.1093/carcin/22.2.287
Tier 2Controlled human skin study
Direct evidence that topical EGCG reduces UV-induced oxidative stress in human skin. Used a purified EGCG preparation, not a sugar scrub; cited for the antioxidant mechanism.
Elmets, C. A., Singh, D., Tubesing, K., Matsui, M., Katiyar, S., & Mukhtar, H. (2001). Cutaneous photoprotection from ultraviolet injury by green tea polyphenols. Journal of the American Academy of Dermatology, 44(3), 425-432. https://doi.org/10.1067/mjd.2001.112919
Tier 2Controlled human study
Dose-dependent reduction of UV-induced redness with topical green tea polyphenols. Supports antioxidant photo-defence as a mechanism; this is not sun protection and is no substitute for sunscreen.
Chiu, A. E., Chan, J. L., Kern, D. G., Kohler, S., Rehmus, W. E., & Kimball, A. B. (2005). Double-blinded, placebo-controlled trial of green tea extracts in the clinical and histologic appearance of photoaging skin. Dermatologic Surgery, 31(7 Pt 2), 855-860. https://doi.org/10.1111/j.1524-4725.2005.31731
Tier 2Randomised controlled trial
Topical green tea cream improved elastic tissue in photoaged skin on histology, though visible clinical change was modest. Used a 10% green tea cream, a different format and dose to a scrub.
Scapagnini, G., Davinelli, S., Di Renzo, L., De Lorenzo, A., Olarte, H. H., Micali, G., Cicero, A. F., & Gonzalez, S. (2014). Cocoa bioactive compounds: Significance and potential for the maintenance of skin health. Nutrients, 6(8), 3202-3213. https://doi.org/10.3390/nu6083202
Tier 2Peer-reviewed review
Reviews cocoa flavanols (epicatechin, catechin) as skin antioxidants. Much of the human data is oral cocoa intake; cited for the flavanol antioxidant mechanism, not as proof a scrub matches those results.
Draelos, Z. D., Draelos, M. M., Feng, S., Madera, Z., & Chen, M. (2024). Topical antioxidant cocoa polyphenol skin penetration. Journal of Cosmetic Dermatology, 23(12), 4072-4076. https://doi.org/10.1111/jocd.16637
Tier 2Small clinical study (n=5)
Shows topically applied cocoa-derived catechin and epicatechin penetrate the outer skin. Very small sample; supports that cacao polyphenols can reach the skin surface, not a specific outcome.
Tang, S.-C., & Yang, J.-H. (2018). Dual effects of alpha-hydroxy acids on the skin. Molecules, 23(4), 863. https://doi.org/10.3390/molecules23040863
Tier 2Peer-reviewed review
Supports the AHA exfoliation mechanism. Discusses AHAs at formulation strengths above what raw rapadura sugar delivers, so the page applies the mechanism, not the magnitude.