Lutein is a xanthophyll that is produced in plants and algae as part of the carotenoid synthesis pathway. Evidence suggests that lutein accumulates in the eyes of mammals including humans, and here it may have protective effects against cataracts and macular degeneration. For example, in one study1, researchers administered 15 mg of lutein three time per week to subjects with age-related cataracts, while other groups received 100 mg α-tocopherol three times per week or a placebo. Serum concentrations of lutein and α-tocopherol increased in both the supplemented groups over a 2 year period but increases were only significant in the lutein group. Visual acuity and glare sensitivity improved only in those subjects receiving the lutein supplement. These results suggest that not all antioxidants are beneficial at protecting the eye from diseases of oxidative stress such as cataracts. Because lutein accumulates in the eye, it and other xanthophylls that also accumulate in the eye are beneficial at protecting the eye from disease.
It is interesting that lutein plasma concentrations increased following consumption of α-tocopherol. This supports the contention that antioxidants work in synergy and increasing one antioxidant spares other antioxidants and can therefore increase their concentrations in tissues. It has been shown for example that vitamin C supplements can increase glutathione peroxidase levels in cells. Lutein is present in spinach and this is one of the best sources of lutein. A 100 gram serving of spinach will provide anywhere between 5 and 15 mg of lutein, in addition to other xanthophylls including zeaxanthin, the latter also being shown to have beneficial effects at preventing disease in the eye. Other sources of lutein include eggs and broccoli, as well as other chlorophyll containing green leafy vegetables such kale. Increasing intakes of these foods may protect the eyes from age-related degeneration caused by ultraviolet light induced oxidative stress. Supplements of lutein are also available and have been shown to be safe.
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