Evidence of the cancer-fighting benefits of cruciferous vegetables is growing, but the results of studies of their effects on breast cancer risk have been inconsistent, states Jane Higdon, Ph.D., of the Linus Pauling Institute. A 2010 study found that a compound in cruciferous vegetables inhibited breast tumor growth in mice. Further research on human subjects may verify that eating broccoli, cauliflower, cabbage and other cruciferous vegetables can lower your risk of breast cancer.
Significance
In botany, cruciferous vegetables are distinguished by the cross-shaped petals of their flowers. In cancer research, these vegetables have distinguished themselves by providing glucosinolates, the sulfur-containing compounds that give cabbage, broccoli and cauliflower their pungent taste and aroma. With the help of enzymes, glucosinolates are broken down to create isothiocyanates when you eat these vegetables. Isothiocyanates suppress the actions of carcinogenic toxins like cigarette smoke, radon or asbestos by interfering with their actions at the cellular level. Cruciferous vegetables also contain indoles, compounds that modify the actions of estrogen in women. Indoles may have an impact on breast cancer risk by altering the effects of estrogen, proposes Higdon.
Research Complications
Epidemiologic studies, based on women's reports of the amounts of cruciferous vegetables they ate and their subsequent incidence of breast cancer, haven't been conclusive. Cooking methods and genetic variations may have reduced the amounts of isothiocyanates that the women were able to absorb, suggests Higdon. Your genetic makeup affects your body's ability to metabolize the chemicals in foods, including the isothiocyanates in broccoli or cauliflower. Heat can inactivate an enzyme in cruciferous vegetables that facilitates the breakdown of glucosinolates into isothiocyanates, reducing the amount of these cancer-fighting compounds that your body can use.
Recent Evidence
In their study of human breast cancer cells implanted in female mice, Renaud Warin, Ph.D., and colleagues found that an isothiocyanate in garden cress and other cruciferous vegetables inhibited cancer cell proliferation and vascularization of cancer tissues. This study, published in "Molecular Carcinogenesis" in 2010, may offer biochemical evidence that compounds in cruciferous vegetables can help prevent breast cancer in humans.
Potential
Warin's study indicates a need for more investigation into the chemopreventive benefits of cruciferous vegetables and their affects on breast tumor growth. Recent research developments on the chemical compounds in cruciferous vegetables and the ways they are influenced by cooking or metabolism may change the way researchers interpret epidemiologic data about diet and breast cancer.
Recommendations
The National Cancer Institute recommends that you eat five to nine servings of vegetables per day as a positive step to prevent cancer, but these guidelines don't include suggestions about cruciferous vegetables. With the growing evidence of the chemopreventive benefits of cabbage, broccoli and other cruciferous vegetables, you might consider making them part of your daily diet. If broccoli, cauliflower and Brussels sprouts don't whet your appetite, explore recipes using kale, collards, watercress, kohlrabi or other less common varieties. Consult your health care provider to learn how you can modify your diet to lower your risk of breast cancer.
