Dermal carotenoid level and kinetics after topical and systemic administration of antioxidants: enrichment strategies in a controlled in vivo study.

BACKGROUND: High doses of sun-emitted UV-radiation induce reactive oxygen species (ROS) as major pro-oxidants thus inducing premature skin aging. The best prevention of the destructive action of free radicals in human skin is textile coverings, topical sunscreens and the development of a high antioxidative protective network.
OBJECTIVE: The effects of topical, systemic and combined application of antioxidants (AO) were investigated on human skin in vivo.
METHODS: Topical application of creams and systemic incorporation of tablets both containing AO was investigated in vivo by resonance Raman spectroscopy.
RESULTS: Topical, systemic and combined AO-treatments induced a statistically significant increase of AO levels in human skin while placebo did not show any changes. The highest accumulation was induced by the combination of topical and systemic AO. Carotenoid-tablets combined with placebo-cream induced less carotenoid accumulation than carotenoid-tablets alone. Carotenoid levelling after the end of treatment lasted for around 2 weeks following the topical application of AOs, and up to 5 weeks after systemic administration, depending on the BMI of volunteers.
CONCLUSION: Topically applied AO are stored in the SC for a short time only due to the rapid AO-depletion by desquamation, textile contact, washing and environmental stress. In contrast to topical application, the systemically applied carotenoids are stored in the body fat tissue and slowly released onto the skin surface with sweat and sebum. The combined topical and systemic application of AO represents an optimal form of protection of the AO-network.