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.
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.)
Current Evidence: AICR/WCRF Expert Report and its Updates (CUP)
After a systematic review of the global scientific literature, AICR/WCRF analyzed how cruciferous vegetables and its nutrients affect the risk of developing cancer. This comprehensive review of decades of research concluded that there is strong – probable - evidence that:
- foods containing dietary fiber DECREASE the risk of colorectal cancer
- a diet high in non-starchy vegetables along with fruits DECREASE the risk of lips, mouth, tongue and other aerodigestive cancers
Evidence categorized as "probable" means there is strong research showing a causal relationship to cancer – either decreasing or increasing the risk. The research must include quality human studies that meet specific criteria and biological explanations for the findings. A probable judgement is strong enough to justify recommendations.
Source: AICR/WCRF. Diet, Nutrition, Physical Activity and Cancer: A Global Perspective, 2018.
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.
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