Foods That Fight Cancer™
Broccoli & Cruciferous Vegetables
Broccoli & Cruciferous Vegetables
The four-petal flowers from these veggies resemble a cross or "crucifer," hence the name. Broccoli is probably the best known cruciferous vegetable. Like Brussels sprouts, rapini, cabbage, cauliflower and turnips (white), it forms a "head." Others - known as the "headless crucifers" - include dark green leafy vegetables like kale and collard greens.
What's in Cruciferous Vegetables?
Nearly all are excellent or good sources of vitamin C and some are good sources of manganese. Dark greens are high in vitamin K.
- Glucosinolates are compounds found in all cruciferous vegetables; Glucosinolates form isothiocyanates and indoles.
Other nutrients and phytochemicals vary:
- Broccoli, Brussels sprouts, cauliflower and rapini are all excellent sources of folate, a B vitamin.
- Broccoli is a good source of potassium.
- Broccoli and Brussels sprouts are good sources of dietary fiber and rich in magnesium.
- Broccoli, Brussels sprouts and rapini contain carotenoids such as beta-carotene.
- Red cabbage and radishes supply anthocyanins Other cruciferous vegetables provide different polyphenols, such as hydroxycinnamic acids, kaempferol and quercetin.
Full Glossary for Foods That Fight Cancer
The Cancer Research
The link between cruciferous vegetables and their components to cancer prevention is relatively well-studied.
AICR/WCRF’s expert report and its updates group cruciferous vegetables – and most green vegetables – as non-starchy. (Corn and potatoes, on the other hand, are examples of starchy vegetables.)
What Current Evidence Shows: AICR/WCRF Expert Report and its Updates (CUP)
Cruciferous vegetables are non-starchy vegetables that contain dietary fiber and carotenoids (including beta-carotene). After a systematic review of the global scientific literature, AICR/WCRF weighed the strength of the evidence linking these factors to lower risk for several cancers.
|Diets high in:||CONVINCINGLY lower risk of the following cancers:|
|Foods containing dietary fiber||Colorectum|
|Diets high in:||PROBABLY lower risk of the following cancers:|
|Non-starchy vegetables||Mouth, pharynx and larynx|
|Foods containing carotenoids||Mouth, pharynx and larynx
Source: Food, Nutrition, Physical Activity, and the Prevention of Cancer: A Global Perspective and the 2011 Continuous Update Project: Colorectal Cancer.
Genetic differences mean that some people retain cruciferous vegetables’ isothiocyanate compounds in the body longer -- and benefit more -- than others.
Open Areas of Investigation: Laboratory Research
Cruciferous vegetables are a large group, and each kind contains numerous vitamins, minerals and phytochemicals studied in the lab for cancer protection. Some of the more well-studied compounds include:
- Glucosinolates, which are broken down into isothiocyanates and indoles. Lab studies have shown these compounds decrease inflammation, a risk factor for cancer. The compounds also inhibit enzymes that activate carcinogens and stimulate enzymes that de-activate carcinogens. Studies suggest the compounds "turn on" genes that suppress tumors, slowing cancer cell growth and stimulating a process called apoptosis in which cancer cells self-destruct. Some studies show that these substances may also shift the active form of estrogen into a weaker form. (High amounts of estrogen are a risk factor for certain hormone-linked cancers.)
- Carotenoids act as antioxidants. Beta-carotene, one of the more well-known carotenoids, also promotes cell communication that helps control abnormal cell growth.
- Vitamin C protects cells as an antioxidant and by supporting the immune system.
- Kaempferol, quercetin and anthocyanins provide antioxidant and anti-inflammatory effects. In cell and animal studies, they slow development of several stages and types of cancer.
- Folate helps maintain healthy DNA and keeps cancer-promoting genes “turned off.” Animal studies, however, suggest that exceptionally high amounts or intervention after cancer cells have formed might promote development of colon and perhaps other cancers.
Open Areas of Investigation: Human Studies
Earlier population studies found a strong link between greater consumption of cruciferous vegetables and lower risk of lung, colorectal, stomach, breast, prostate and other cancers. Among more recent, well-designed studies, the specific link between cruciferous vegetables and reduced cancer risk is not as consistent or strong. One reason may have to do with specific gene-diet interactions that are only now coming to light. For example, scientists recently found that about half of the population does not carry a specific gene involved in determining how long the body retains -- and utilizes -- protective cruciferous compounds from the diet.
More research is underway, including intervention trials investigating the possibility that isothiocyanates might interfere with prostate cancer progression.
Quite a few studies link consuming too little dietary folate with increased risk of colorectal cancer or pre-cancerous polyps. Recent studies also show a link between relatively high amounts of folic acid -- the form of folate found in supplements and fortified foods -- and increased risk of colorectal cancer. There is no evidence that consuming high amounts of foods naturally high in folate increases cancer risk.
In the Kitchen
- Choose compact, firm heads heavy for their size with no soft spots and no off-odors.
- Green leaves should be fresh with no yellowing.
- Turnips are sweetest when small.
- Wait to wash until just before use.
- Refrigerate in an unsealed plastic bag: broccoli, cauliflower and turnips for up to 5 days; others up to a week.
- Steam, microwave, stir-fry or sauté to retain glucosinolates, folate and vitamin C. Boiling greens in a pot of water can cut content of these substances in half.
- Cook just until tender-crisp, with greens still bright. Overcooking makes them smelly and unattractive.
- Many are also delicious roasted or baked, especially turnips, Brussels sprouts, broccoli and cauliflower.
- Add to soup, or make them the star on their own.
- Many are delicious raw, perhaps dipped in hummus or spread with peanut butter. If the flavor, for example of Brussels sprouts, is too strong to enjoy raw, steam or blanch briefly, cool quickly in ice water and serve cold.
- Enjoy the depth of flavor they add to green salads.
- Try broccoli sprouts on salads or in sandwiches.
Cauliflower, Cabbage and Carrot Salad
- 1 small cauliflower, cut into florets
- 1 cup finely shredded red cabbage
- 2 medium carrots, grated
- 1 small red onion, finely chopped
- 1/4 cup chopped walnuts
- 2 Tbsp. chopped fresh parsley
- 1 Tbsp. white vinegar
- 1 tsp. Dijon mustard
- 1 Tbsp. extra virgin olive oil
- 1 Tbsp. low-fat mayonnaise
Toss together cauliflower with cabbage, carrots, onion, walnuts and parsley.
Whisk together vinegar, mustard. Add oil and mayo and whisk.
Drizzle over salad and mix well.
Makes 6 servings.
Per Serving: 90 calories, 6 g total fat (1 g saturated fat), 7 g carbohydrates, 2 g protein, 2 g dietary fiber, 70 mg sodium.
Below are answers to some of the most frequently asked questions we get asked.
Which fruits and vegetables should I be eating?
Eat as many different vegetables and fruits as you can. Variety is the key to obtaining the many protective phytochemicals. Each vegetable and fruit has its own profile of health-promoting substances.
The phytochemicals found in cantaloupe are different from those in broccoli or leeks or cherries. Try to include a lot of colors on your plate. Aim to eat some bright red, green, orange, blue, purple and yellow vegetables and fruits each day.
Should I buy organic foods whenever possible?
There are many reasons to eat organic foods, but currently, there is no convincing evidence that shows a difference between organic and conventionally grown foods related to cancer risk. Studies show pesticide residues on conventionally grown foods are almost always within safety tolerance limits.
If you are concerned about pesticide residues and can afford to spend more, organic produce may be a choice for you. Eating generous servings of a large variety of veggies and fruits - whether organic or not will benefit your health. The advantages of including more vegetables and fruits in your diet outweigh the potential risks from pesticides.
Can grilled meats really cause cancer?
Lab studies show that exposing meats to direct flame, smoke and intense heat (like when you grill or broil) can cause the formation of carcinogens (cancer-causing substances). Cooking methods that involve less heat, such as microwaving, baking, steaming and poaching, do not promote the formation of these substances.
Several strategies you can use to cut carcinogen formation on meat include marinating, flipping frequently, removing excess fat from meat before cooking, and microwaving for part of the cooking time. So for delicious and healthful options, try grilling vegetables, veggie burgers and fruit slices and cut down on meat, fish and poultry.
- Cavell, B.E., et al., Anti-angiogenic effects of dietary isothiocyanates: mechanisms of action and implications for human health. Biochemical pharmacology, 2011. 81(3): p. 327-36.
- Ambrosone, C.B. and L. Tang, Cruciferous vegetable intake and cancer prevention: role of nutrigenetics. Cancer prevention research, 2009. 2(4): p. 298-300.
- Zhang, Y., Cancer-preventive isothiocyanates: measurement of human exposure and mechanism of action. Mutation research, 2004. 555(1-2): p. 173-90.
- World Cancer Research Fund / American Institute for Cancer Research, Food, Nutrition, Physical Activity and the Prevention of Cancer: a Global Perspective, 2007: Washington, DC. p. 82-113.
- Keum, Y.S., W.S. Jeong, and A.N. Kong, Chemoprevention by isothiocyanates and their underlying molecular signaling mechanisms. Mutation research, 2004. 555(1-2): p. 191-202.
- Keck, A.S. and J.W. Finley, Cruciferous vegetables: cancer protective mechanisms of glucosinolate hydrolysis products and selenium. Integrative cancer therapies, 2004. 3(1): p. 5-12.
- Dashwood, R.H. and E. Ho, Dietary histone deacetylase inhibitors: from cells to mice to man. Seminars in cancer biology, 2007. 17(5): p. 363-9.
- Clarke, J.D., et al., Differential effects of sulforaphane on histone deacetylases, cell cycle arrest and apoptosis in normal prostate cells versus hyperplastic and cancerous prostate cells. Molecular nutrition & food research, 2011. 55(7): p. 999-1009.
- Gibellini, L., et al., Quercetin and cancer chemoprevention. Evidence-based complementary and alternative medicine : eCAM, 2011. 2011: p. 591356.
- Calderon-Montano, J.M., et al., A review on the dietary flavonoid kaempferol. Mini reviews in medicinal chemistry, 2011. 11(4): p. 298-344.
- Duthie, S.J., Folate and cancer: how DNA damage, repair and methylation impact on colon carcinogenesis. Journal of inherited metabolic disease, 2011. 34(1): p. 101-9.
- Du, W., et al., Folate and fiber in the prevention of colorectal cancer: between shadows and the light. World journal of gastroenterology : WJG, 2010. 16(8): p. 921-6.
- Kim, M.K. and J.H. Park, Conference on "Multidisciplinary approaches to nutritional problems". Symposium on "Nutrition and health". Cruciferous vegetable intake and the risk of human cancer: epidemiological evidence. The Proceedings of the Nutrition Society, 2009. 68(1): p. 103-10.
- Giovannucci, E., et al., A prospective study of cruciferous vegetables and prostate cancer. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology, 2003. 12(12): p. 1403-9.
- Seow, A., H. Vainio, and M.C. Yu, Effect of glutathione-S-transferase polymorphisms on the cancer preventive potential of isothiocyanates: an epidemiological perspective. Mutation research, 2005. 592(1-2): p. 58-67.
- Lee, S.A., et al., Cruciferous vegetables, the GSTP1 Ile105Val genetic polymorphism, and breast cancer risk. The American journal of clinical nutrition, 2008. 87(3): p. 753-60.
- Yang, G., et al., Isothiocyanate exposure, glutathione S-transferase polymorphisms, and colorectal cancer risk. The American journal of clinical nutrition, 2010. 91(3): p. 704-11.
- Traka, M., et al., Broccoli consumption interacts with GSTM1 to perturb oncogenic signalling pathways in the prostate. PloS one, 2008. 3(7): p. e2568.
- Richman, E.L., P.R. Carroll, and J.M. Chan, Vegetable and fruit intake after diagnosis and risk of prostate cancer progression. International journal of cancer. Journal international du cancer, 2011.
- Kubo, A., et al., Dietary factors and the risks of oesophageal adenocarcinoma and Barrett's oesophagus. Nutrition research reviews, 2010. 23(2): p. 230-46.
- Musa-Veloso, K., et al., Influence of observational study design on the interpretation of cancer risk reduction by carotenoids. Nutrition reviews, 2009. 67(9): p. 527-45.
- Gallicchio, L., et al., Carotenoids and the risk of developing lung cancer: a systematic review. The American journal of clinical nutrition, 2008. 88(2): p. 372-83.
- Kim, D.H., et al., Pooled analyses of 13 prospective cohort studies on folate intake and colon cancer. Cancer causes & control : CCC, 2010. 21(11): p. 1919-30.
- McKillop, D.J., et al., The effect of different cooking methods on folate retention in various foods that are amongst the major contributors to folate intake in the UK diet. The British journal of nutrition, 2002. 88(6): p. 681-8.
- Song, L. and P.J. Thornalley, Effect of storage, processing and cooking on glucosinolate content of Brassica vegetables. Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 2007. 45(2): p. 216-24.
- McNaughton, S.A. and G.C. Marks, Development of a food composition database for the estimation of dietary intakes of glucosinolates, the biologically active constituents of cruciferous vegetables. The British journal of nutrition, 2003. 90(3): p. 687-97.
- Cartea, M.E., et al., Phenolic compounds in Brassica vegetables. Molecules, 2011. 16(1): p. 251-80.
- Shaughnessy, D.T., et al., Inhibition of fried meat-induced colorectal DNA damage and altered systemic genotoxicity in humans by crucifera, chlorophyllin, and yogurt. PloS one, 2011. 6(4): p. e18707.
- Zhang, Y., Allyl isothiocyanate as a cancer chemopreventive phytochemical. Molecular nutrition & food research, 2010. 54(1): p. 127-35.