Zeaxanthin is a natural substance found in yellow or green vegetables, but especially in leafy green vegetables like spinach and kale. It is also found in egg yolks. Scientists are studying zeaxanthin and the prevention of lung cancer.
One article (1) discussed zeaxanthin and the prevention of lung cancer. In a six-year study of more than 58,000 men in the Netherlands, zeaxanthin was able to prevent lung cancer in men who took the substance along with lutein.
Zeaxanthin is also used in age-related macular degeneration, the prevention of cataracts, and the prevention of atherosclerosis. Because the study was done using a large number of patients, it can safely be said that eating a diet high in zeaxanthin could prevent lung cancer, at least among men.
Source: 1.Lutein and Zeaxanthin. http://www.nutri-facts.org/en_US/nutrients/carotenoids/lutein-and-zeaxanthin/disease-risk-reduction.html. Accessed 9/7/16.