Dark Green Leafy Vegetables
Spinach, kale, romaine lettuce, leaf lettuce, mustard greens, collard greens, chicory and Swiss chard are excellent sources of fiber, folate and a wide range of carotenoids such as lutein and zeaxanthin, along with saponins and flavonoids.
According to AICR’s (American Institute of Cancer Research) second expert report, foods containing carotenoids probably protect against cancers of the mouth, pharynx and larynx. Foods containing folate decrease risk of pancreatic cancer and that foods containing dietary fiber probably reduce one’s chances of developing colorectal cancer.
Researchers believe that carotenoids seem to prevent cancer by acting as antioxidants removing potentially dangerous “free radicals” from the body before they can do harm. 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.
Garlic belongs to the family of vegetables called Allium, which also includes onions, scallions, leeks and chives. According to AICR’s report, foods belonging to the allium family of vegetables probably protect against stomach cancer. Moreover, the evidence in the report shows that garlic, in particular, probably decreases one’s chances of developing colorectal cancer. The protective effect of garlic was shown to have a dose response relationship. In other words, highest exposure to the food showed the greatest decrease in risk.
These allium vegetables contain many substances now being studied for their anti-cancer effects, such as quercetin, allixin and a large group of organosulfur compounds that includes allicin, alliin and allyl sulfides.
In laboratory studies, components of garlic have shown the ability to slow or stop the growth of tumors in prostate, bladder, colon and stomach tissue. one garlic component, called diallyl disulfide, exerts potent preventive effects against cancers of the skin, colon and lung. Recently, this compound proved able to kill leukemia cells in the laboratory. A compound derived from garlic called ajoene has displayed similar activity. Components in Allium vegetables have slowed the development of cancer in several stages and at various body sites: stomach, breast, esophagus, colon and lung.
The tomato’s red hue comes chiefly from a phytochemical called lycopene. Tomatoes have attracted particular attention from prostate cancer researchers because lycopene and its related compounds tend to concentrate in tissues of the prostate.
AICR’s second expert report, found substantial and convincing evidence that foods containing lycopene probably protect against prostate cancer.
In animal models, consumption of tomato compounds has been linked to large decreases in prostate cancer risk. Moreover, there is evidence that this cancer-fighting potential is increased if tomatoes are consumed in a processed form that allows these natural compounds to be released and more easily absorbed, such as tomato sauce, tomato paste or tomato juice.
Lycopene, a powerful antioxidant, together with a group of related compounds collectively called the “red family,” has displayed anti-cancer potential. In the laboratory, tomato components have stopped the proliferation of several other cancer cells types, including breast, lung, and endometrial.
Although the evidence suggests it is likely that foods containing lycopene, including tomatoes, offer cancer protection, AICR stresses the importance of eating a variety of plant foods to ensure the most protection against cancer development. No food in isolation can effectively lower cancer risk.