Written by Dr. Jessica Moore
Beans, beans the magical fruit, the more you eat the more…. you might prevent colon cancer?
With ~26,800 new diagnosis of colorectal cancer (CRC) in 2017, CRC is regarded as the 2nd most commonly diagnosed cancer in Canada. Interestingly, the consumption of legumes has been shown to inhibit colon carcinogenesis (the initiation and development of a cancer). Legumes include beans (navy, black, adzuki, kidney, pinto, lima, fava etc), chickpeas, soybean, lentils and green peas.
Most CRCs develop from adenomas. Advanced adenomas are considered the most relevant precursor in the development of CRC. A study of 2079 men and women, from the polyp prevention trail, showed that a higher intake of beans was associated with a reduction in recurrence of advanced adenoma by 65%. Another study in 186 men and women suggested that diets high in dried beans, split peas, or lentils were associated with a reduced risk of colon cancer by 81% compared to those seldom eating legumes.
Legumes may inhibit carcinogenesis via a multitude of different but synergistic mechanisms. Flavinoids and lignans, found in legumes, have been observed to inhibit tumor growth, promote normal cell activity and support the body’s natural process for cell death in cancer cells, “apoptosis”. In addition to flavonoids and lignans, legumes are also a good source of protein and provide micronutrients such as selenium, vitamin E, vitamin B6 and other B vitamins. Although studies are conflicting, some studies suggest that intake of B6 in particular, is inversely associated with colon cancer risk.
Legumes are a good source of dietary fiber, which aids in bulking the stool, maintaining bowel regularity and supporting normal detoxification. This means toxins are eliminated rather than left sitting against the colon wall for long periods of time. Fiber aids in the health of your normal gut bacteria. With the help of your gut bacteria, some of the fiber in legumes is converted to short chain fatty acids, such as butyrate. Butyrate is nutritionally important for healthy colon cells but may also have beneficial effects on tumor growth inhibition and apoptosis (normal cell death in a cancer cell).
As part of colon cancer prevention, you can talk with your doctor or other healthcare providers about the addition of legumes to your diet. Safe and appropriate exercise habits and standard colon cancer screening are important risk reduction activities as well.