Lutein - the antioxidant found in dark green leafy vegetables such as spinach and kale - has been proven to reduce our risk of developing the eye disease age-related macular degeneration (AMD).
AMD is the most common cause of deteriorating eyesight in the over 50s, and it's a problem that can accelerate quickly among cigarette smokers.
Researchers have been split over the effectiveness of the antioxidants - including vitamins A, C, E, zinc and beta-carotene - in preventing, or slowing, AMD.
But a new study has confirmed that lutein is the most effective antioxidant after studying the progress of a group of 4,519 participants aged between 60 and 80. Most of the group's lutein intake was from food rather than from supplements.
The single greatest source of lutein is from raw kale, followed by cooked kale, cooked spinach, cooked collards or cabbage.
(Source: Archives of Ophthalmology, 2007; 125: 1225-1232).