The objective of this systematic review was to assess whether dietary intake of lutein and zeaxanthin (L/Z) helps maintain vision in adults. Lutein and zeaxanthin, are xanthophyll carotenoids naturally present in food, especially in dark green leafy vegetables, such as spinach and kale, as well as eggs - in the egg yolk. Eggs have been found to be a particularly bioavailable source of these carotenoids.