Effect of a Supplement Containing Olive Leaf Extract against Ultraviolet Light-Induced Tanning: A Double-Blind Placebo-Controlled Study

Abstract

Numerous studies have been conducted to research substances useful for preventing or reducing pigmentation in the skin. Pigment spot is a serious cosmetic concern, particularly for the Asian elderly. Oral ingestion of antioxidant supplements is known to prevent skin pigmentation. Glutathione is an intracellular antioxidant that plays an important role in cell protection against oxidative stress and shows antimelanogenic activity. In our previous study, it was shown that olive leaf extract stimulated intracellular glutathione synthesis in human fibroblasts, melanocytes and keratinocytes. Here, a double-blind placebo-controlled study was performed to investigate whether the ingestion of a supplement containing olive leaf extract, L-cystine and ascorbic acid affects tanning of skin induced by ultraviolet (UV) irradiation. We determined the minimal erythema dose (MED) in 24 healthy volunteers before and after supplementation. Small sites on the subjects'arms were exposed to UV light for three successive days, and subjects were then administered tablets containing 47.7 mg olive leaf extract, 40.0 mg L-cystine and 50.0 mg ascorbic acid every day for 8 weeks. The present study showed that the subjects'MED increased significantly after an 8-week course of supplementation. The increment of skin lightness at the sites of UV irradiation from Day 10 to Day 17 was significantly higher in the test sample group than in subjects who received a placebo. These results suggest that the supplement containing olive leaf extract, L-cystine and ascorbic acid reduces UV-induced erythema and tanning by its antioxidative activity.