Green beans or string beans are the unripe pods of common beans (Phaseolus vulgaris). Green beans are a good dietary source of vitamin C, vitamin K, folate, potassium, phosphorus, manganese, magnesium, calcium, iron, zinc and fiber. Green beans also contain carotenoids such as beta-carotene and lutein, as well as the flavonols quercetin and kaempferol. Lutein has been found to protect against both cataracts and age-related macular degeneration in the eye. The high chlorophyll (which is green) content of green beans masks their high carotenoid content.
Breast cancer-related effects of eating green beans
Green bean components beta-carotene, lutein, quercetin, and kaempferol have all been found to be associated with lower risk of breast cancer. However, no population studies have been performed that specifically identified an association between green bean consumption and risk of breast cancer.
Green beans lose some of their antioxidant capacity when boiled; other cooking methods are preferable. Frozen beans lose less of their antioxidant activity than canned beans. One study found that up to 24% of the flavonol contents of green beans was leached into the cooking water during commercial processing. Non-organic green beans must be washed very thoroughly to remove pesticide residue as much as possible.
Haricots verts is the French name for green beans. True French green beans are longer and more narrow than common U.S. varieties. The Chinese long bean or yardlong bean (Vigna unguiculata subsp. Sesquipedalis) is a type of cowpea.
Note that while we are continually searching for new evidence specifically concerning this food, there is not much interest in it among breast cancer researchers, so few studies are available.