Cruciferous Vegetables

By Joel Fuhrman, M.D.

Enjoy The Benefits Of The Most Healthful Foods In The World!

With the growing popularity of nutritional supplements, more and more Americans are looking for accurate information about the nutrients that can make a real difference in their health and longevity. The reality is, however, that the most powerful thing you can do to improve your health is to eat more green vegetables. Americans eat a piddling amount of greens. If they ate a lot more, disease rates of all types would plummet. Not only are vegetables rich in vitamins and minerals, they also contain thousands of phytochemicals that are critically important for our health.

As researchers have looked more deeply into nutritional science, it has become widely known that eating a whole-food, plant-based diet is a far better way to get your nutrients than fiddling around with supplements of various individual nutrients. And the very best way to get the benefits of this superior nutrition is to harness the power of high-nutrient super foods. Not all vegetables are created equal, and one of the most fascinating areas of research in the last 10 years has been the therapeutic value of cruciferous vegetables. Cruciferous vegetables are those in the broccoli and cabbage family and include such foods as bok choy, radishes, and watercress.

Close to 300 case-controlled studies have shown a protective effect of vegetable consumption against cancer, and cruciferous vegetables have the most powerful anticancer effects of all foods. Studies have shown that eating fresh fruits, beans, vegetables, seeds, and nuts reduces the occurrence of cancer. If consumption of plant food intake goes up 20% in a population, cancer rates typically drop 20%. But cruciferous vegetables have been shown to be twice as effective. As cruciferous vegetable intake goes up 20% in a population, cancer rates drop 40%.1

Most of the phytonutrients we hear about (vitamin C, vitamin E, beta-carotene, lutein, and lycopene) function as antioxidants in your body, meaning that they neutralize free radicals, rendering them harmless. The phytochemicals in cruciferous vegetables do this and more; they also activate your body’s own built-in antioxidant control system.

When you take in otherwise natural antioxidants such as vitamin C and E in the form of isolated supplements, they fight little one-on-one skirmishes against free radicals, but not much more. Their beneficial effects are gone in a few hours. Synthetic or isolated fractions of vitamin E, beta-carotene, or vitamin C are even less effective and also can cause pro-oxidant behavior, creating more of the free radicals that you are trying to fight.

The benefits of the glucosinolates in whole green vegetables are vastly superior. Instead of getting short-lived benefits (or outright harm),the unique compounds in cruciferous vegetables cycle over and over, protecting your body for 3-5 days after consumption. They fuel numerous bodily systems already in place, enabling them to function more effectively. These systems defend not only against free radicals, but many other types of damage, as well.

Cancer Protection

Compounds derived from cruciferous vegetables are our best defense against cancer-causing chemicals in the environment. They inactivate chemical carcinogens before the initiation of cancer can occur, and they enable the removal of these substances from our tissues by a synergistic enhancement of detoxifying enzyme activity. They also can block the formation of tumors initiated by chemicals in lab animals and kill cells that have demonstrated DNA damage, protecting against noncancerous conditions, such as fibroid tumors, as well.

Cruciferous vegetables help detoxify carcinogens and other toxins, rendering them harmless. They also upregulate the liver’s ability to remove toxins, remove free radicals, prevent oxidative and DNA damage in cells, transform hormones into beneficial compounds inhibiting hormone- sensitive cancers, enhance and protect against the age-related loss of cellular glutathione, and enable cell death in cells that have abnormal mutations and DNA damage.2


A perfect example is a study on prostate cancer showing 28 servings of vegetables per week decrease risk of prostate cancer by 33%, but just 3 or more servings of cruciferous vegetables per week decreased risk of prostate cancer by 41%.3

The National Cancer Institute of the National Institute for Health recommends 9 servings of fruit and vegetables per day. I recommend 6 fresh fruits per day and 8 servings of vegetables, with at least 2 servings of cruciferous vegetables per day (one raw and one cooked). Do you eat green cruciferous vegetables daily?

Phytochemicals At Work

Cruciferous vegetables contain phytochemicals that have unique abilities to modify human hormones, detoxify compounds, and prevent toxic compounds from binding to human DNA, preventing toxins from causing DNA damage that could lead to cancer.

Cruciferous vegetables are unique in that they are rich sources of sulfurcontaining compounds known as glucosinolates. It is the presence of glucosinolates that makes a vegetable earn the designation of cruciferous. There have been over 120 glucosinolates identified. These compounds help produce other healthful compounds, which is important since humans do not absorb glucosinolates well.

Myrosinase is an enzyme that is compartmentalized (separated) in the cell walls of cruciferous vegetables. It is released only when the cell walls are damaged (for example, via chewing, chopping, blending, or juicing), at which point it catalyzes the conversion of glucosinolates into isothiocyanates (ITCs) such as indole-3-carbonole. These ITCs are well absorbed and have potent and diverse beneficial effects in humans and other animals.

Myrosinase is deactivated by cooking. The more the food is heated, the more is lost. As a result, fewer isothiocyanates are produced when we cook and overcook these vegetables. Maximum levels of these highly potent anticancer compounds are available from raw vegetables that are somewhat bitter, such as broccoli sprouts, watercress, and arugula. The very high levels of isothiocyanates (ITCs) produced by these foods give that “bitter” taste. However, myrosinase also is produced by the gut flora, so absorption of compounds derived from cruciferous vegetables is still possible from cooked greens.

Sulforaphane, broccoli’s much studied compound, is an isothiocyanate that has a unique mechanism of action. This compound blocks chemical-initiated tumor formation and induces cell cycle arrest in abnormal cells, meaning that it inhibits growth and induces cell death in cells with early cancerous changes in a dose-dependent manner (i.e., the more you eat, the better). Recent studies show that the amount of sulforaphane derived from eating a reasonable amount of broccoli can have dramatic effects to protect against colon cancer.4

The Hormonal Connection

Your body produces hormones that function as chemical messengers to help control its function. These messengers can take many forms—beneficial or harmful, depending on how well or how badly we eat. The consumption of cruciferous vegetables has been shown to shift hormonal balance to more favorable hormonal compounds. Isothiocyanates form compounds such as diindolylmethane (DIM), which help the body transform estrogen and other hormones into forms that are more easily excreted from the body. Estrogen and testosterone have a functional role in the body, but too much of them and too much of the wrong type can be disease-promoting (such as increasing the risk of breast and prostate cancer). Postmenopausal hormonal replacement therapy has been shown to increase the risk of breast cancer and heart disease.

Cruciferous Vegetables and Cancer

Cruciferous vegetables have been shown to have a direct effect on human cancer cells, and these effects have been confirmed by numerous animal studies and with human cell lines. Juicing cruciferous vegetables is strongly recommended and has been shown to markedly inhibit the growth of breast cancer with significant death of cancer cells occurring at higher concentrations of cruciferous juice.5 Isothiocyanates (ITCs) also have been shown to promote cell death in most common cancers, such as colon cancer, cervical cancer, and prostate cancer.

There are various ITCs such as phenylethylisothiocyanate (PEITC), diindolylmethane (DIM), and indole- 3-carbinol (I3C) that all work synergistically at different cellular loci to promote excretion of carcinogens and induce killing of cells that are dysplastic or that have cancerous changes. Isothiocyanates also have been shown to have other important immunologic benefits. They ameliorate systemic lupus in mice, inhibit herpes virus replication, and inhibit human papilloma virus. <>

Some ITCs With Known Biologic Anticancer Activity

ITCs with known biologic anticancer activity include: sulforaphane, PEITC, allyl isothiocyanate, indole-3- carbinol, and 3,3-diindolylmethante.

One should be cautious of trying to use supplements of these compounds instead of the whole food source. For example, indole-3- carbinol, which is converted to other beneficial metabolites such as DIM, can produce other metabolites that may be tumor promoters if taken in isolation. Taking a supplement of this compound outside of the food containing it could have untoward effects, especially if one has cancer.

The Thyroid Connection

Isothiocyanates were in the past considered goitergens (anti-nutrients) that inhibit the uptake of iodine by the thyroid gland. However, this no longer thought to be significant in humans.

Nutritional Excellence

Lastly, while everyone eventually jumps on the “cruciferous vegetables are good for you” bandwagon, let’s not forget H = N/C (Health = Nutrient intake divided by Calorie intake). In other words, besides all of their unique features, green cruciferous vegetables still contain more vitamins and minerals per calorie than any other foods.


 1. Michaud DS; Spiegelman D; Clinton SK. “Fruit and vegetable intake and incidence of bladder cancer in a male prospective cohort.” J Natl Cancer Inst 1999; 91(7):605-13.

2. Gamet-Payrastre L; Lumeau S; Cassar G. “Sulforaphane, a naturally occurring isothiocyanate, induces cell cycle arrest and apoptosis in HT29 human colon cancer cells.” Cancer Res 2000;60(5):1426-1433.

3. Cohen JH; Kristal AR; Stanford JL. “Fruit and vegetable intake and prostate cancer risk.” J Nat Can Inst 2000;92(1):61-68.

4. Gamet-Payrastre L; Li P, Lumeau S; et al. “Sulforaphane, a naturally occurring isothiocyanate, induces cell cycle arrest and apoptosis in HT29 human colon cancer cells.” Cancer Res 2000;60:1426-1433.

5. Brandi G; Schiavano GF; Zaffaroni N; et al. “Mechanisms of action and antiproliferative properties of Brassica oleracea juice in human breast cancer cell lines.” J Nutr 2005;135(6):1503-9.

6. Skibola CF; Smith MT. “Potential health impacts of excessive flavonoid intake.” Free Radic Biol Med 2000;29:375-383. Galati G; O'Brien PJ. “Potential toxicity of flavonoids and other dietary phenolics: significance for their chemopreventive and anticancer properties.” Free Radic Biol Med 2004;37(3):287- 303.

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