The ultraviolet A component of sunlight causes both acute and chronic damage to human skin. In this study the potential of epicatechin, an abundant dietary flavanol, and 3'-O-methyl epicatechin, one of its major in vivo metabolites, to protect against UVA-induced damage was examined using cultured human skin fibroblasts as an in vitro model. The results obtained clearly show that both epicatechin and its metabolite protect these fibroblasts against UVA damage and cell death. The hydrogen-donating antioxidant properties of these compounds are probably not the mediators of this protective response. The protection is a consequence of induction of resistance to UVA mediated by the compounds and involves newly synthesized proteins. The study provides clear evidence that this dietary flavanol has the potential to protect human skin against the deleterious effects of sunlight. (C) 2003 Elsevier Inc.