In recent years, there has been a lot of interest in the cruciferous family of vegetables due to their cancer fighting compounds. Broadly, cruciferous vegetables belong to the Cruciferae family.
In general, these are cold-weather vegetables and have flowers that have four petals so that they resemble a cross. Cruciferous family of vegetables includes the following: Arugula, Bok Choy, Broccoli, Brussels Sprouts, Cabbage, Cauliflower, Collard Greens, Horseradish, Kale, Radishes, Rutabaga, Turnips, Watercress, Wasabi.1
Anti-Cancer Effects Of Cruciferous Vegetables
Cruciferous family of vegetables is full of super-foods with powerful anti-cancer effects:2
- Cruciferous vegetables are rich in nutrients, including several carotenoids (beta-carotene, lutein, zeaxanthin) which are the colorful plant pigments, some of which body can turn into Vitamin A. Carotenoids are powerful antioxidants that can help prevent some forms of cancer and heart disease.
- Cruciferous vegetables are also a rich source of fiber, vitamins C, E, and K; folate; and minerals.
- In addition, cruciferous vegetables contain a group of substances known as glucosinolates, which are sulfur-containing chemicals. According to the National Cancer Institute, the cancer-killing ability of cruciferous veggies has been attributed to the presence of glucosinolates.
- Glucosinolates are known to break down during the chewing and digestion process into biologically active compounds that prevent cancer cells growth. These compounds are referred to as indoles, thiocyanates and isothiocyanates.3
- Glucosinolate hydrolysis products help prevent cancer by enhancing the elimination of carcinogens (cancer-causing agents) before they can damage DNA, or by altering cell-signaling pathways in ways that help prevent normal cells from being transformed into cancerous cells.
Studies and experiments on animals have identified several potential ways in which glucosinolates may help prevent cancer. Glucosinolates:
- Are anti-inflammatory.
- Contain antibacterial and antiviral properties.
- Inactivate carcinogens.
- Reprogram cancer cells to die-off.
- Prevent tumor formation and metastasis.
- Help protect cells from DNA damage.
Cancer Prevention With Cruciferous Vegetables
Researchers have investigated possible associations between intake of cruciferous vegetables and the prevention of various types of cancers as listed below:
1. Lung Cancer
Epidemiological evidence suggests that intake of cruciferous vegetables may be inversely associated with lung cancer risk. Cruciferous vegetables, which are rich in isothiocyanates, may protect against lung cancer.
The Isothiocyanates may inhibit the activation of carcinogens found in tobacco smoke and may also enhance excretion of carcinogenic metabolites before they can damage DNA.
In particular, cruciferous vegetables (broccoli, cabbage, cauliflower, Brussels sprouts, kale) have been suggested to have anti-cancerous properties that may contribute to reduced risk for lung cancer.4
2. Prostate Cancer
According to studies, cruciferous vegetables – especially broccoli, cabbage and their cruciferous cousins may substantially reduce the risk of prostate cancer.5
Additionally, the most recent prospective study found that intake of cruciferous vegetables was inversely associated with metastatic prostate cancer — cancer that has spread beyond the prostate (i.e. late-stage prostate cancer).6
This means that people who ate greater amounts of cruciferous vegetables had a lower risk of developing prostate cancer.7
3. Breast Cancer
Cruciferous vegetables are unique because they are rich in sulfur containing compounds called glucosinolates – which supports detoxification and indole-3-carbinol – which greatly reduces the risk of breast cancer.
Among postmenopausal women, cruciferous vegetables consumption significantly increases the urinary ratio of certain compounds which is inversely associated with breast cancer risk.
One case-control study found that women who ate greater amounts of cruciferous vegetables had a lower risk of breast cancer.8
4. Colorectal Cancer
Colorectal adenomas (non-cancerous tumors that may affect various organs) are the precursors of most colorectal cancers. The effect of diet in relation to colorectal adenomas and adenoma recurrence was explored in several studies.
Cruciferous vegetables were modestly associated with reduced risk of colorectal adenoma. Diets high in cruciferous vegetables were found to confer protection against colorectal adenomas and subsequently, colorectal carcinoma.9
Intake Recommendations Of Cruciferous Vegetables
Although many organizations, including the National Cancer Institute, recommend eating a variety of fruits and vegetables daily; separate recommendations for cruciferous vegetables have not been established.
The results of some epidemiological studies suggest that adults should aim for at least five weekly servings of cruciferous vegetables. However, still much remains to be learned regarding cruciferous vegetables consumption and cancer prevention.10