Spinach, kale, romaine lettuce, leaf lettuce, mustard greens, collard greens, chicory, dandelion and Swiss chard are excellent sources of fiber, folate and a wide range of and flavonoids.
Carotenoids are a group of phytonutrients that lend the red, orange and yellow hues to fruits and vegetables...beta-carotene, lycopene, lutein, etc.. Carotenoids are present in all living organisms, but humans are not able to make them and must get them from food.
Carotenoids seem to prevent cancer by acting as antioxidants. Some laboratory research has found that the carotenoids in dark green leafy vegetables can inhibit the growth of certain types of breast cancer cells, skin cancer cells, lung cancer and stomach cancer.
The Second Expert Report noted probable evidence that foods containing folate decrease risk of pancreatic cancer and that foods containing dietary fiber probably reduce one’s chances of developing colorectal cancer.