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Life Extension Magazine April 2013
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Shield Yourself from Environmental Cancer Risks

By Steve Frankel
man using microscope  

Shampoos, pesticides, drinking water, plastics, and vehicle emissions contain cancer-causing toxins that we are exposed to on a daily basis.

These chemicals can ultimately lead to cancer by damaging our DNA and impeding our detoxification pathways.1-4  In a cruel twist, some of these toxins even activate cancer-causing genes that could otherwise have remained dormant.5,6

Today, it is impossible to avoid the constant onslaught of environmental toxins. But what is possible is to equip your body with the tools it needs to identify toxins and remove them from your system before they can cause any damage.

Cruciferous vegetables do just that. They optimize your body’s detoxification system in order to neutralize many of these chemical threats—and maintain the integrity of your DNA in the process.7-9

Decades of research have shown that ingesting cruciferous vegetables can slash risk of cancer by up to 54%.10-18 These findings show reduced risk of virtually every major type of cancer.19-29

In this article, you’ll learn about the specific components of cruciferous vegetables that fight cancer—and, more importantly, you’ll discover how to harness the powers of cruciferous vegetables to maximize their cancer-fighting benefits.

Reducing the Effect of Environmental Toxins

Cruciferous vegetables (cabbage family, broccoli, cauliflower, mustard greens, and Brussels sprouts) are some of the most powerful cancer-fighters nature has to offer. Numerous studies have shown that consuming cruciferous vegetables can sharply reduce your risk of cancer.10-18

They’ve been found to be effective against a vast array of cancers including breast, prostate, colon, lung, bladder, ovarian, kidney, and more. Compounds in cruciferous vegetables also have been found to provide long-term anticancer protection even after they’ve been cleared from the body!30,31

No other food group can boast such powerful, broad-reaching anti-cancer benefits. We’ve known for years that people with the highest overall intake of cruciferous vegetables experience a substantial reduction in the risk of many kinds of cancer—now we’re starting to understand why.

Research has shown that the compounds in cruciferous vegetables have the ability to control cancer’s on/off switch.32-35  Essentially, they help fight against cancer either by activating genes that prevent cancer, or by suppressing genes that cause cancer.36,37

Environmental toxins affect the growth and spread of cancer. Pollutants found in air, water, soil, and a large number of industrial products (especially plastics) contain toxins with cancer-causing potential.1-4

Our bodies are equipped with enzyme systems to fight off toxic threats.3,38 Unfortunately, if your enzyme systems aren’t functioning properly, they can have the opposite effect: They can activate those toxins, causing them to become even more lethally carcinogenic. Making matters worse, some toxins suppress protective enzymes, impairing their ability to protect us from cancer.2,7,38-41

That’s where cruciferous compounds come in. Cruciferous compounds help support the key enzyme systems that are so vital for detoxifying your body of harmful, cancer-causing environmental toxins.9,42,43 The result is unprecedented protection from many of the unavoidable cancer-causing toxins we face on a daily basis.

The Most Common Cruciferous Vegetables
The Most Common Cruciferous Vegetables
  • Arugula
  • Black and brown mustard
  • Bok choy
  • Broccoli
  • Brussels sprouts
  • Cabbage
  • Cauliflower
  • Collard greens
  • Horseradish
  • Japanese radishes
  • Kale
  • Kohlrabi
  • Parsnips
  • Radishes
  • Rape
  • Rutabaga
  • Turnips
  • Watercress
  • Wasabi

Glucosinolates: Powerful Chemoprevention

Among cruciferous vegetables’ many powerful components, one group stands out. They’re called glucosinolates, which are found in broccoli and broccoli sprouts. They are converted within the body to a number of active constituents that fight cancer through multi-targeted mechanisms.44-47

For example:

  • Glucosinolates reduce the carcinogenicity of many environmental toxins by boosting the genetic expression of important detoxifying enzymes.8,48
  • They protect DNA from oxidative damage caused by toxins (up to 28% reduction in human research), thereby preventing the initial changes that can lead to cancer.49
  • Glucosinolate derivatives encourage cancer cells to commit suicide, and they suppress genes that create the new blood vessels that support rapid growth of tumors.50
  • Finally, there’s evidence that glucosinolate derivatives can turn off genes that promote the spread of cancer.50

Because glucosinolates directly affect the function and expression of genes (the epigenetic effect), experts point out that their protective effects are both wide-ranging and long-lasting.50

Human research reveals that higher dietary intakes of glucosinolates are associated with a reduction in prostate cancer risk by 32%.45 Derivatives of the glucosinolates abundant in broccoli sprouts help prevent stomach cancer by killing the H. pylori bacterium. They also reduce symptoms and biomarkers of inflammation in infected individuals.51

It’s important to note that cooking cruciferous vegetables reduces the rate of glucosinolate conversion to active molecules by about 300%, which is one good reason why supplementation may offer a better alternative.52-54

What You Need to Know
dirt smoke form the coal plant

Slash Your Cancer Risk with Cruciferous Vegetables

  • Environmental toxins are a growing problem, threatening to raise already high rates of preventable cancers.
  • While our bodies contain systems capable of detoxifying harmful chemicals, some enzyme systems in fact activate potential carcinogens, making them more, not less, likely to produce malignancy.
  • Toxins, radiation, and other forces exert negative epigenetic effects on our chromosomes, potentially revealing cancer-causing genes for activation.
  • Phytochemicals from cruciferous vegetables can attack these natural cancer-promoting processes at their root.
  • Cruciferous components work together to inhibit toxin-activating enzymes, boost detoxifying enzymes, and reverse negative epigenetic changes in our chromosomes.
  • Because many such compounds are inactivated by cooking, consider using a concentrated supplement containing extracts from multiple types of beneficial cruciferous plants.

Indole-3 Carbinol (I3C)

Indole-3-carbinol (I3C) is one of the most widely-studied components of cruciferous vegetables. Studies have shown that it helps fight cancers of the breast, prostate, and reproductive tract, as well as colon and blood cancers.55

In cancers of the reproductive tract, I3C helps prevent the development of tumors by benefitting important ratios of estrogen metabolites such as the 2-hydroxyestrone:16a-hydroxyestrone ratio and 2-hydroxyestrone:estriol ratios.56-58 Note that 2-hydroxyestrone is an estrogen metabolite that seems to protect against cancer, whereas 16-hydroxyestrone may promote cancer.

Treatment with I3C has also been shown to have a positive effect on recurrent respiratory papillomatosis, a precancerous condition that produces growths in the throat and voice-box. Studies show that treatment with I3C completely stops the growth of papilloma in about 33% of patients and reduces the growth rate and need for surgery in another 33% of patients.59,60

I3C is also beneficial in early cervical cancers known as carcinoma in situ. In one study, 50% of the patients receiving 200 mg/day of  I3C had complete regression of carcinoma in situ, while none of the patients in the placebo group were found to be free of carcinoma in situ after 12 weeks.61 And in women with a potentially pre-cancerous condition known as vulvar intraepithelial neoplasia, treatment with 200 or 400 mg/day of I3C reduced the size and severity of lesions on the vaginal labia.62

Animal studies of I3C show a reduction in tumor number and size in experimental models of cancers of the breast, lung, and prostate.63-65

Beneficial Anticancer Hormone Effects of Cruciferous Vegetables

Many cancers, especially those of the reproductive tissues, depend on the presence of sex hormones (primarily estrogen and testosterone) to sustain their growth. Therefore, many treatment approaches rely on blocking or reducing levels of sex hormones in cancer victims. The problem is, conventional drugs can cause side effects and may harm reproductive potential. That’s where cruciferous vegetables come in.

Some components of cruciferous vegetables act more gently and by multiple mechanisms to impede the growth of such hormone-dependent cancers, making them an important part of chemoprevention strategies.

Phenethyl isothiocyanate (PEITC), a natural metabolite of glucosinolates from watercress, has been found, for example, to down-regulate androgen receptors, minimizing stimulation of prostate cancer by testosterone.94 3,3’-Diindolylmethane (DIM), another glucosinolate metabolic product, prevents stimulation of prostate cancer cells by both androgens and estrogen.69,95,96

Breast cancers are commonly estrogen-dependent; sulforaphane and indole-3-carbinol (I3C), still other glucosinolate products, decrease the amounts of cancer-stimulating estrogen receptor-alpha molecules present on cells, inhibiting their proliferation.97,98 This effect has been shown to be active in thyroid cancers as well, which are much more common in women than in men.66,99 DIM has a complementary effect, stimulating cancer-suppressing estrogen receptor-beta molecules.100

Finally, a late 2012 study revealed that I3C also induces degradation of the pro-cancer estrogen receptor alpha, and at the same time reduces expression of tumor-promoting insulin-like growth factor receptor-1 in breast cancer cells.101

Thus, a single serving of a complete cruciferous vegetable supplement can protect reproductive tissues from a whole array of harmful hormonal influences, potentially making you much less likely to develop these devastating malignancies.

Di-indolyl-methane (DIM)

Chemist at work  

The compound DIM is produced in the body following ingestion of glucosinolates derived from cruciferous vegetables. Animal models, basic lab studies, and limited phase 1 clinical trials show that DIM prevents tumors of the prostate, ovary, cervix, and thyroid, as well as several types of leukemia.66-73 DIM also appears to suppress cancer stem cells, the lingering, super-potent cells that can cause a cancer to recur even years after apparently successful treatment.74,75

Like the other components of cruciferous vegetables, DIM induces cancer cell death by apoptosis, inhibits cancer cell growth, slows or stops new blood vessel development in tumors, and can inhibit factors allowing cancer cells to invade healthy tissue.69

Like I3C, DIM helps prevent the growth of estrogen-dependent tumors, such as those of the female breast and reproductive tract, by boosting the ratio of 2-hydroxyestrone:16a-hydroxyestrone.66,76

Studies in mice demonstrate that DIM can completely prevent the progression of pre-cancerous lesions of the cervix, caused by human papilloma virus (HPV), to full-blown cancer.77 In fact, researchers now theorize that DIM could possibly make the human papilloma virus vaccine more effective, so that it could be given to women already infected with the virus. (Currently it is only effective prior to infection.)77 DIM also increases levels of protective interferon gamma in mouse models of cervical cancer.68

Watercress Extract

One particular cruciferous vegetable, watercress, brings together the very best actions of the other cruciferous vegetables and their components we’ve discussed so far. Studies have shown that watercress has a positive effect on lung, colorectal, and prostate cancers.

Watercress is especially rich in another glucosinolate derivative, called phenethyl-isothiocyanate (PEITC).78 PEITC inhibits carcinogen-activating enzymes, induces cancer detoxification enzymes, and protects against DNA damage.78,79 PEITC is also a remarkably specific epigenetic modulator that turns on genes that suppress cancer.80,81

These effects make watercress extracts particularly appealing in the case of some of our most potent environmental carcinogens, such as those found in tobacco smoke.82-84 Watercress and PEITC are also showing promise in other malignancies caused by activated carcinogens, such as colorectal and prostate cancers.85-87

Look for supplements that contain watercress extract, rather than purified PEITC, because the watercress extracts also contain small amounts of other detoxifying enzyme inducers with even greater potency.78 These substances help prevent cancer growth by reducing inflammatory stimuli such as nitric oxide.88

Cancer Risk Reduction by Cruciferous Vegetables
Cancer Cells

Cancer Type

Risk Reduction

Colorectal

49%13

Melanoma Skin Cancer

46%17

Prostate

42%20

Pancreas

34%19

Kidney

32%15

Bladder

31%11

Esophagus

28%12

Ovary

24%18

Lung

22%16

Breast

17%12

Mouth and Throat

17%12

This table shows the reduction in risk for various cancer types, for those consuming the highest versus the lowest amounts of cruciferous vegetables.

How to Get the Most Benefit from Cruciferous Vegetables

In order to get the maximum health benefits from cruciferous vegetables, make sure you’re consuming a variety of them. Every member of the cruciferous family contains a different set of the glucosinolates that help fight cancer.

For example, broccoli, Brussels sprouts, and cabbage are good sources of a glucosinolate called glucoraphanin, the precursor of sulforaphane. Watercress is an excellent source of the glucosinolate gluconasturtiin, the precursor of PEITC. And garden cress, cabbage, and Indian cress are top sources of a glucosinolate known as glucotropaeolin, the precursor of benzyl isothiocyanate (BITC).

Next, make sure they’re not overcooked. Boiling, steaming, and microwaving at high power substantially decreases the bioavailability of cruciferous vegetables’ cancer-fighting compounds.89-92As beneficial for you as cruciferous vegetables are, there are some things you need to be aware of: The glucosinolate content varies greatly even among individual plants of the same type—and even among parts of the same plant. Even these relative concentrations change during the course of a single plant’s growth cycle.93

That’s why, in addition to eating a variety of cruciferous vegetables, it’s important to take a standardized cruciferous compound supplement. A good cruciferous vegetable supplement should contain I3C, DIM, and PEITC—and for even greater impact, should also include extracts of raw broccoli, cabbage, watercress, and other plant compounds such as apigenin.