Leafy greens such as green leafy lettuce, broccoli, and turnip tops contain 10 to 100 times the level of Vitamin A, a potent antioxidant, than other vegetables and fruit.  Researchers from the Galician Public Foundation for Health Emergencies (Spain) studied the dietary intakes of 295 Spanish residents with lung cancer and 322 healthy counterparts.  The team found that the subjects who consumed at least one portion daily of green leafy vegetables were at a 50% reduced risk for lung cancer. Consumption of other vegetables, such as tomatoes and green beans, showed a protective but non-significant effect; as well, fruit was only nominally protective. 

Incorporate tasty green leafy vegetables such as bok choy, broccoli, collard greens, dark green leafy lettuce, kale, mesclun, mustard greens, romaine lettuce, spinach, turnip greens, and watercress in to your daily diet, choosing the greens that are locally available as the season permits.