Influence of supplementation with a curly kale extract on cutaneous carotenoids, radical scavenging activity and skin lipids

Antioxidants are well known to prevent cell damage, premature skin aging and skin cancer because they neutralize free radicals which are formed by stress, UV irradiation and other oxidative noxes. Carotenoids can be enriched in the skin by nutrition and recently it could be shown that skin with high level of cutaneous carotenoids correlate with a younger skin. The question arises whether orally administered extract from curly kale (Brassica oleracea L. ssp. oleracea var. sabellica L.) rich in carotenoids increase cutaneous carotenoids, and if this increase is correlated with an increase in radical scavenging activity and radical protection of the skin. The cutaneous carotenoid concentration was measured with in vivo Raman spectroscopy, the radical scavenging and protection with in vivo electron paramagnetic resonance spectroscopy. Furthermore, the skin lipid profile was investigated applying HPTLC on skin lipid extracts. A double blind placebo controlled clinical study was performed with 24 healthy volunteers. The verum group has shown a slow but significant increase of cutaneous carotenoids and a significant increase in radical scavenging activity of the skin combined with a significant protection against stress induced radical formation after 8 weeks supplementation. Furthermore, the skin lipids in the verum group increased compared to the placebo group but only significantly for ceramide [NS]. These results indicate that a supplementation with dietary products containing carotenoids in physiological concentrations can protect the skin against reactive oxygen species and could avoid premature skin aging and other radical associated skin diseases.