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Consumption of Cruciferous Vegetables Reduces the Risk for Several Cancer Types

Summary: Studies suggest that regular consumption of vegetables from the cruciferous family, which include cauliflower, broccoli, and cabbage, may reduce the risk of several types of cancer. A major prospective dietary study conducted in Europe found a reduced incidence of a type of lung cancer common in male smokers and reduced cancer of the upper digestive tract among people who regularly (every day) ate cauliflower and cabbage. A second U.S. study showed a lower incidence of a type of lymph node cancer with higher vegetable consumption. Cruciferous vegetables contain beneficial compounds called glucosinolates that are broken down into cancer-fighting byproducts when digested.

Cauliflower belongs to the cruciferous vegetables family (Cruciferae), which includes broccoli, cabbage, collard greens, mustard greens, radishes, Brussels sprouts, and kale. Cruciferous vegetables are rich in glucosinolates, compounds that produce the characteristic spicy, some would say bitter, flavor of these vegetables when they are crushed, chewed or cooked. Digestion breaks down glucosinolates into a number of bioactive substances shown to produce beneficial health effects, notably cancer prevention. Epidemiological studies suggest that regular dietary intake of cruciferous vegetables, including cauliflower and cabbage, may lower the risk for developing several cancers, including those of the breast, digestive tract, prostate, and lung.

A major prospective dietary study, the European Prospective Investigation into Cancer and Nutrition (EPIC), followed the dietary habits and health of 521,468 subjects in 10 European countries between 1991-2000. (1) After an average follow-up of almost 9 years, 1,830 people were diagnosed with lung cancer. Regular consumption of cauliflower and cabbage by current smokers was associated with a 23% reduction in the risk for squamous cells carcinoma, one of the most common forms of lung cancer, particularly in men who smoke. Another analysis from the EPIC study found an almost 50% reduced risk of cancer of the upper digestive tract (oral cavity, pharynx, larynx, and esophagus) among people who ate the most cauliflower and cabbage (34 grams per day) compared with those who ate the least (3 grams per day). (2)

A second large prospective study of more 35,150 women living in Iowa between the ages of 55 and 69 found a 12% reduced risk for non-Hodgkin’s lymphoma (NHL), a cancer of the lymph nodes, among women who had the highest consumption of cruciferous vegetables, including cauliflower and broccoli. The women were followed for 20 years, during which time 415 cases of NHL were diagnosed. (3) Of interest, of a number of antioxidant compounds called flavanoids tested, high intake of one type, proanthocyanidins, were associated with a significant risk reduction for NHL. Proanthocyanidins, found in high concentrations in apples, apple cider and cranberry juice, are known to inhibit a number of processes related to cancer development, including angiogenesis, inflammation, and cellular proliferation.

The anti-cancer effects of cruciferous vegetables have been attributed to several byproducts of glucosinolates, and in particular to isothyiocyanates and indole-3-carbinol (I3C). (4) One form of isothyiocyanate, benzyl isothiocyanate (BITC), has attracted a great deal of research interest because of its ability to inhibit chemically induced cancer in animal models. BITC inhibits the growth of cultured breast cancer cells by promoting apoptosis (programmed cell death), as well as suppressing lung and liver carcinogenesis. Recently, BITC was found to inhibit angiogenesis, the growth of new tumor blood vessels, in a mouse model of breast cancer. I3C has numerous anti-cancer properties, such as inhibiting cancer cell proliferation, inducing cell death, modulating hormone receptors, suppressing angiogenesis, and possibly re-sensitizing some types of cancer to chemotherapy.

By Roderick Smith, M.S.


References

1. Büchner FL, Bueno-de-Mesquita HB, Linseisen J, et al. Fruits and vegetables consumption and the risk of histological subtypes of lung cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC). Cancer Causes Control 2010 Mar;21(3):357-71.

2. Boeing H, Dietrich T, Hoffmann K, et al. Intake of fruits and vegetables and risk of cancer of the upper aero-digestive tract: the prospective EPIC-study. Cancer Causes Control 2006 Sep;17(7):957-69.

3. Thompson CA, Habermann TM, Wang AH, et al. Antioxidant intake from fruits, vegetables and other sources and risk of non-Hodgkin's lymphoma: the Iowa Women's Health Study. Int J Cancer 2010 Feb 15;126(4):992-1003.

4. Aggarwal BB, Ichikawa H. Molecular targets and anticancer potential of indole-3-carbinol and its derivatives. Cell Cycle 2005 Sep;4(9):1201-15. Epub 2005 Sep 6.



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