Premature aging of the skin is mainly caused by exposure to UV light. The antioxidant capacity of the skin can be compromised by moderate exposure to UV light. Therefore, bolstering the antioxidant defense system of the skin is a potentially important strategy for reducing environmentally induced skin damage. A clinical trial conducted at Saint Eugenio Hospital, Rome, investigated the effect of the carotenoids on skin physiology parameters, such as surface lipids, hydration, photoprotective activity, skin elasticity and skin lipid peroxidation . The team of researchers led by P Palombo demonstrated that the combined oral and topical treatment of lutein and zeaxanthin provided significant antioxidant protection activity in the skin. But also oral or topical administration individually provided this protection.
Astner S and co-workers of the Massachusetts General Hospital, Boston, tested the protective effect of oral administration of lutein and zeaxanthin in mice . They measured the photo-damage and photocarcinogenesis after exposing the mice to UVB radiation. Treatment with lutein and zeaxanthin significantly reduced skin fold thickness and number of infiltrating mast cells following UVB irradiation. The phytochemicals also increased tumor-free survival time, reduced tumor multiplicity and total tumor volume. The study concluded that oral intake of lutein and zeaxanthin protects the skin against UVB-induced photoaging and photocarcinogenesis.
 Beneficial long-term effects of combined oral/topical antioxidant treatment with the carotenoids lutein and zeaxanthin on human skin: a double-blind, placebo-controlled study. Skin Pharmacol Physiol. 2007;20(4):199-210. Epub 2007 Apr 19.
 Dietary lutein/zeaxanthin partially reduces photoaging and photocarcinogenesis in chronically UVB-irradiated Skh-1 hairless mice. Skin Pharmacol Physiol. 2007;20(6):283-91.