You are what you eat—Or are you? Exploring dietary versus topical antioxidants in skin aging

Antioxidants are considered to be powerful agents in delaying skin aging by impeding the action of free radicals that play an integral role in the pathogenesis of this process, especially in photoaging. Antioxidants also signal through the native oxidant defense pathway NRF2, which causes the activation of antioxidant response element target gene expression. A range of naturally occurring antioxidants including isothiocyanates, polyphenols, vitamins, and carotenoids seem to delay skin aging, some of which activate the NRF2 pathway. The structures of certain antioxidants, such as resveratrol, prevent adequate penetration of the skin barrier, suggesting that oral delivery could be more effective. Additionally, certain antioxidants, including vitamin C, are essential nutrients and thus must be included in the diet. There is a need to determine the ideal delivery method for each antioxidant and, in some cases, to develop novel delivery methods. In this review, the current understanding of antioxidant mechanisms and their role in skin aging will be explored as well as oral/dietary and topical routes for use as anti-aging treatments in the future.