Studying the anticancer benefits of dry beans, scientists have discovered that different market classes of beans help in reducing the risk of mammary cancer.
For the study, researchers at Colorado State University studied the anticancer activity of six market classes of bean including; small red, great northern, navy, black, dark red and white kidney bean in the diet of laboratory animals.
They also evaluated whether the level of antioxidants or seed coat pigments in the bean were related to mammary cancer.
The researchers fed cooked dry bean powder from the six market classes and a control group without beans in the diet to laboratory rats in a standard preclinical model for breast cancer.
The dry bean powders were also evaluated for antioxidant capacity, phenolic and flavonoid content; all factors thought to be associated with anticancer activity.
After chemical analysis of the beans, it was found that total phenolic and flavonoid content varied widely among market classes and the differences were strongly associated with seed coat colour; where coloured beans had ten times or greater phenolic and flavonoid content compared to white beans.
Antioxidant capacity of the beans also varied widely among dry bean market classes and were highly related to seed coat colour, where coloured beans had approximately two to three times greater antioxidant capacity than white beans.
Dry bean consumption from every market class reduced cancer incidence (number of animals with one tumour) and tumour number per animal compared to the control group.
Cancer incidence was reduced from 95 percent in the control group to 67 percent in animals fed beans. The average number of malignant tumours was also reduced from 3.2 in the control group to 1.4 tumours per animal in the group fed bean.
No associations were observed between phenolic content, flavonoid content and antioxidant capacity with cancer among the bean market classes.
The findings clearly suggest that the anticancer activity in dry bean is not associated with seed color or antioxidant capacity.
Researchers are now investigating the mechanisms and molecules that contribute to the anticancer properties of dry bean.
Clinical trials are also underway to determine if bean in the diet of humans are associated with biomarkers for cancer incidence.
Results from the study were published in the recent issue of the journal Crop Science.