The effects of increasing lutein and zeaxanthin dosages in people with age-related macular degeneration (AMD) are discussed.
AMD is a disorder of the macula, the area associated with the sharpest visual acuity. AMD is classified as dry (nonneovascular) or wet (neovascular) and is associated with several risk factors, the biggest being age. The pathogenesis of AMD is unknown. Like many chronic illnesses, prevention is a key factor for managing AMD. Lutein and zeaxanthin, natural xanthophylls not synthesized by the human body, have been investigated for their use in promoting visual health. Lutein and zeaxanthin are dietary carotenoids that are components of a normal diet. The mechanism of protection that they confer is unknown, but two mechanisms have been hypothesized. Several studies have been conducted to assess the relationship between plasma levels of lutein and zeaxanthin and the risk of developing AMD and have yielded conflicting results. Increased dietary intake of or supplementation with lutein and zeaxanthin was found to result in increased plasma levels, which were positively and significantly associated with macular pigment optical density. Limited data have suggested that supplementation may also improve visual function. The optimal dose of lutein and zeaxanthin for the prevention or treatment of AMD has not yet been defined.
A definite association between lutein and zeaxanthin supplementation and clinical benefit has yet to be shown; however, it may still be an appropriate cautionary measure for patients at high risk for developing AMD.