![]() ![]() In infants, the macular levels of L are higher than those of Z, probably due to differences in transport mechanisms that are not yet completely developed. Interestingly, the content of carotenoids diminishes significantly, by a factor of 100, moving away from the macula. The presence of L has also been demonstrated in peripheral regions of the fovea, but its content decreases in the central region where Z is prevalent by a 2:1 ratio. Lutein is found mainly in the inner plexiform layer and in Henle’s fiber layer but it can also be found in Müller cells. With zeaxanthin (Z), another xanthophyll, L is the main carotenoid in the human macula, so that the two compounds are mostly referred to as macular pigments (MP). ![]() ![]() However, an important chemical difference with functional implications is the presence of two oxygen atoms inside the structure, thus making L a polar carotenoid which is classified as a xanthophyll, namely an oxygenated carotenoid. The structure of L is similar to that of other carotenoids, with a skeleton made up of 40 carbon atoms, organized into eight isoprene units, as shown in Figure 1. We reviewed the literature on the evidence for the health effects of L, including its usual intake with different diets, adequate doses, and safety of supplementation, with specific reference to eye diseases. Overall, it seems that the amount of L intake, including by supplementation, may partly counter inflammatory processes and favor human health, but inconsistencies still remain. More recently, a number of studies have suggested that L may indeed have favorable effects via anti-inflammatory activity, improving cognitive functions, and decreasing the risk of cancer, cardiovascular diseases and other systemic conditions. Furthermore, no univocal data concerning the appropriate dosage for possible L supplementation had been found. However, conflicting data had been reported concerning L efficacy, and in 2006, it was claimed that no compelling evidence had been provided concerning the supposed beneficial effect of L on human health. Several studies have shown that high L intake, either through diet or as nutritional supplement, has beneficial effects on eye diseases, preventing or even improving both age-related macular degeneration (AMD) and cataract. Lutein is a xanthophyll, i.e., an oxygenated carotenoid that all mammalians, humans included, derive from their diet because they are unable to synthesize carotenoids. Most studies have focused on lutein (L), a carotenoid with a strong antioxidant effect in vitro that has been associated with a reduced risk of age-related diseases. In recent decades, there has been increasing interest in their effects on health a high dietary intake of carotenoids has been associated with beneficial effects in several systemic diseases and in eye disorders, with protection of the retina from phototoxic light damage. Carotenoids are nutrients widely distributed in foods, especially in fruit and vegetables, and appear to have antioxidant properties. Therefore, based on the most recent findings, this review will focus on lutein properties, dietary sources, usual intake, efficacy in human health, and toxicity.Ī large body of evidence suggests that a diet rich in antioxidants, which have an anti-inflammatory role, may contribute to reducing the burden of chronic diseases. However, there are also conflicting data concerning lutein efficacy in inducing favorable effects on human health and there are no univocal data concerning the most appropriate dosage for daily lutein supplementation. In general, sustained lutein consumption, either through diet or supplementation, may contribute to reducing the burden of several chronic diseases. At present, the available data have been obtained from both observational studies investigating lutein intake with food, and a few intervention trials assessing the efficacy of lutein supplementation. ![]() Furthermore, many studies have reported that lutein may also have positive effects in different clinical conditions, thus ameliorating cognitive function, decreasing the risk of cancer, and improving measures of cardiovascular health. In particular, lutein is known to improve or even prevent age-related macular disease which is the leading cause of blindness and vision impairment. A large body of evidence shows that lutein has several beneficial effects, especially on eye health. Lutein is a carotenoid with reported anti-inflammatory properties. ![]()
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