Cabbages and Cancer: the Most Powerful Cancer Prevention Tools We Now Have

We Already Know That Cabbage-Family Foods Reduce Cancer Risk … Now, Scientists Have Discovered the Active Ingredient – and it Works By Balancing Your Estrogen Metabolism

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We all know Grandma was right when she told us to eat our vegetables. With varying degrees of enthusiasm, some of us have been doing so, especially those of us approaching Grandma’s age. Over the last decade or so, researchers have added their findings to Grandma’s advice, concluding in one after another study that more vegetables in our diets help reduce our risk of heart disease, strokes, cancer and other ailments. So what’s new about eating our vegetables?

Researchers into sex-hormone-related cancers (breast, prostate, uterus, ovaries) have discovered that natural substances found in specific vegetables may help lower our sex- hormone-related cancer risk by predictably altering estrogen metabolism in at least one specific way strongly associated with lower cancer risk. Other researchers suggest that specific hormone supplementation may decrease the risk of breast cancer in pre-menopausal women with a family history of this disease.

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There’s enough research in medical and scientific journals to make a review worthwhile, and though absolute conclusions can’t be drawn, there’s enough data to allow us and our physicians to improve our chances of preventing sex-hormone-related cancer.

I promise to keep what follows in plain English. However, for those who get bored with research findings and the inevitable background discussion – and just want a bottom line, here it is:

  • To significantly cut our risk of prostate, breast, uterine, ovarian and other sex-hormone-related cancers, eat more flaxseed (the seed itself, not the oil) as well as cabbage, cauliflower, Brussels sprouts, broccoli, and soy.
  • In addition to eating the right vegetables and seeds, there are some safe, natural supplements to use, specifically: di-indolylmethane, chrysin (for men), and Vitex Agnes (for women). Iodine, as we will see later, is another possibility. These supplements may cut the risk of sex-hormone-related cancers by balancing estrogen metabolism in a very specific way described below.
  • In some cases, progesterone or DHEA supplementation might be indicated.
  • Lycopene may also be useful for prevention of cancer, prostate and others, but the way in which lycopene lowers cancer risk isn’t known.
  • It’s also important to know that more and more tests are becoming available, at reasonable (and even low) prices, to help assess the risk of sex-hormone-related cancer. (See Medical Tests to Assess Sex-Hormone-Related Cancer Risk).

Sex Hormones and Cancer

This topic has been of increasing concern since the introduction of so-called “hormone replacement therapy”: methyl-testosterone for men in the 1940s, and horse estrogen (Premarin) for women in the 1960s, both of which have been proven to increase cancer risk. We won’t waste any ink or further space on these ridiculous, but patentable, “treatments”, except to predict that our descendants will put them in the same category of “historically bad ideas” as chemotherapy and radiation to “cure” cancer and bleeding George Washington to death.

Those of us who are “into” natural medicine have turned to the logical alternative: Natural Hormone Replacement (NHR), using hormones identical in every way to the ones our own bodies produce, in quantities to which our bodies are accustomed, on schedules for which our bodies are already “programmed”. In this way, we hope to minimize our risk of cancer from hormone ingestion while maximizing our chances of preventing heart and blood vessel disease, osteoporosis, and cognitive decline. [For extensive discussion of natural hormone replacement, see the books Natural Hormone Replacement for Women Over 45 by myself and John Morgenthaler, and Maximize Your Vitality and Potency for Men Over 40 by myself and Lane Lenard, Ph.D.]

Of course, sex-hormone-related cancer has been on a decades-long uptrend among those of us who never took a molecule of hormone replacement. Young women as well as old are developing more breast cancers than ever before, and the rate of prostate cancer is climbing among men, most of whom haven’t taken testosterone. Our entire adult population, whether “into” natural medicine and natural hormone replacement or not, has at least a theoretical interest in not developing and perhaps dying of sex-hormone-related cancers.

Cutting Hormone-Related Cancer Risk: Cabbages Versus Cancer

Let’s go over the most recently reported research first, especially since there’s a bit of “local Seattle pride” involved.

Researchers at the Fred Hutchinson Cancer Research Center have just reported1 that three “healthy portions” of vegetables daily cut the risk of prostate cancer by 48%. More pertinent here, they also found that three half-cup “servings” per week of cabbage, cauliflower, Brussels sprouts, or broccoli decreases the risk of prostate cancer by 41%!

So what’s so powerful about these particular vegetables? They’re all members of the Brassica family, also termed cruciferous vegetables, and all contain (among many other things) a phytochemical called indole-3-carbinol, as well as a much more powerful phytochemical termed di-indolylmethane, which is actually just two indole-3-carbinol molecules attached chemically to each other.

These Are Possibly the Most Powerful Cancer Prevention Tools We Now Have

Di-indolylmethane and indole-3-carbinol, as well as the vegetables containing them, have all been shown to reduce risk of cancer, by balancing your estrogen metabolism in a very specific way. These vegetables reduce the amount of a particularly carcinogenic estrogen (16a-hydroxyestrone), which is normally in your body, while increasing a neutral-to-favorable estrogen (2-hydroxyestrone). (For more details on the 2/16a-hydroxyestrone-ratio theory of cancer, see the article called Is Estrogen Carcinogenic?).

But this is estrogen metabolism…how does that affect prostate cancer? Well, this is where the testosterone-to-estrogen cancer hypothesis comes into play. This theory states that once testosterone is transformed into estradiol, whether a little or a lot, then some of that estradiol may get converted 16a-hydroxyestrone (remember this is the “bad estrogen”). At this point the added 16a-hydroxyestrone will exert the same negative influence in the prostate as it does in the breasts and other tissues in women. The worst case result: prostate cancer.

So, if the risk of prostate cancer is reducible by 41% using three half-cups weekly of cabbage, or broccoli, or Brussels sprouts, or cauliflower…imagine how much more reduction we might obtain with additional amounts of these vegetables, or with supplemental di-indolylmethane.

Other experimenters have shown that broccoli consumption2 as well as supplemental indole-3-carbinol3 improves the “2/16a-hydroxyestrone” ratio. Di-indolylmethane has been shown to be the most potent natural inducer of 2-hydroxyestrone production4 and is roughly 10 times more potent than indole-3-carbinol.

There is as yet no direct prospective study in humans that Brassica vegetables, indole-3-carbinol, or di-indolylmethane will reduce breast, uterine or ovarian cancer risk. However, Bradlow3 lists the many inverse correlations between conditions and items that raise or lower breast cancer risk and higher or lower 2/16a-hydroxyestrone ratios.

These inverse correlations are quite suggestive, but correlations cannot prove a case; for example, some third factor may be responsible for both sides of the correlation. However, until the evidence is in, I’m confident that prospective studies of Brassica vegetables, indole-3-carbinol, or di-indolylmethane will show the same tendency to prevent breast, uterine, and endometrial cancers as did this Brassica vegetable and prostate cancer study.

Flaxseed Versus Cancer

In another very recently reported study, 28 postmenopausal women were asked to add 0, 5, or 10 grams (28 grams is one ounce) of ground flaxseed to their usual diets. According to the report8: “Flaxseed supplementation significantly increased urinary 2-hydroxyestrone secretion (p‹0.005) and the urinary 2/16a-hydroxyestrone ratio (p‹0.05) in a linear, dose response fashion.” Translated: in this study, the more flaxseed, the more significant the improvement in the 2/16a-hydroxyestrone ratio. While this was not a direct study of breast or other estrogen-related cancer prevention, it is another very suggestive bit of evidence. While not specifically addressing the 2/16a- hydroxyestrone hypothesis, previous studies of population groups have shown that both flax and soy can help reduce cancer risk.

Soy (With Isoflavones) Versus Cancer

As noted in Natural Hormone Replacement for Women Over 45, various animal studies have shown that genistein, a soy isoflavone, significantly retards the growth of breast cancers. (This effect has not been proven in women). However, in another suggestive study, researchers examined the effects of soy with and without isoflavones9 on the 2/16a-hydroxyestrone ratio. They reported that soy with 150 milligrams of isoflavones daily significantly increased this ratio (p‹0.005), while the same amount of soy without isoflavones did not.

As noted above, previous studies have shown that both soy and flax appear to reduce cancer risk. Whether the mechanism involves their effect on the 2/16a-hydroxyestrone ratio, some as-yet unmeasured effect on 4-hydroxyestrone and its metabolites, another unknown effect, or a combination of factors isn’t known. However, the ability to measure the “2/16a-ratio” gives us a start towards assessing estrogen-related cancer risk.

Iodine (and Iodide) Versus Cancer?

Years ago, when applying Dr. John Myers very effective iodine therapy for fibrocystic breast disease (see Nutrition and Healing for July 1995) some of the women had 24-hour urine tests for estrone, estradiol, and estriol. To my surprise, in the majority of these women the quantity of estriol greatly increased, and the total quantity of estrone and estradiol (combined) decreased following the iodine treatment.

Since estradiol and estrone can metabolize to estriol only through 16a-hydroxyestrone theoretically it appears that iodine somehow greatly stimulated this pathway. Also theoretically, this may mean that iodine helps to “drain away” 16a-hydroxyestrone (“bad estrogen”) by helping to turn it into estriol.

At the time, it was not possible to check this theory, but it can now easily be done with a combination of the tests reviewed here (see Medical Tests to Assess Sex-Hormone-Related Cancer Risk).

“Lugol’s solution”, a combination of iodine and potassium iodide, was used in the “Myers treatment” noted above. As large amounts of iodine or iodide can possibly affect the thyroid adversely, it’s best to work with a physician if using this material or other relatively high-dose iodine and/or iodide preparations.

A historical note: Max Gerson, M.D., the famous diet and cancer cure physician of the early and mid 1900s, maintained that iodine was a major tool in cancer treatment.

DHEA, Progesterone, and Vitex (Chasteberry) Versus Cancer

For pre-menopausal women, it seems very possible that bringing low levels of DHEA up to normal will cut breast cancer risk. At present, supplementation of DHEA itself appears to be the best way to do this. For women after menopause, I often recommend improvement of DHEA levels by supplementation to help in prevention of cancer in general as well as for improvement in immune system function.

The herb Vitex agnus castus (chasteberry) can improve progesterone levels for some pre-menopausal women. For others, as well as for women after the menopause, supplementation of progesterone is needed.

For Men: Chrysin Versus Cancer?

For men, the flavonoid chrysin (isolated from a species of Passion Flower) may also aid in cutting cancer risk. Men metabolize testosterone directly to estradiol; chrysin inhibits this transformation. (Naringenin, another flavonoid, also inhibits this transformation but not quite as strongly as chrysin). If we subscribe to the testosterone-to-estrogen theory for prostate cancer, then it seems logical that anything which slows this transformation down would also cut cancer risk.

Unfortunately, there are no studies of chrysin and cancer prevention yet available. If chrysin can be shown to favorably alter before and after testosterone-to-estrogen-ratio tests for men, then (again theoretically) the risk of cancer should be lessened. However, as noted above, it may also be additionally useful to promote a favorable 2/16a-hydroxyestrone ratio (with cabbages, broccoli, or supplemental di-indolylmethane) in whatever estrogen remains to further lower men’s prostate cancer risk.

Lycopene Versus Prostate Cancer

Lycopene is not known at present to alter sex-hormone-related metabolites, but it’s included here for sake of completeness. In a comprehensive review10,11 Dr. E. Giannuci writes: “Among 72 studies identified, 57 reported inverse associations between tomato intake or blood lycopene level and the risk of cancer….35 of these inverse associations were statistically significant…..The evidence of benefit was strongest for cancers of the prostate, lung, and stomach. Data were also suggestive of benefit for cancers of the pancreas, colon and rectum, esophagus, oral cavity, breast, and cervix.” However, he cautions that a cause-effect relationship cannot be definitively established.

In one well-publicized recent study, men scheduled for prostate cancer surgery were asked to use either lycopene or placebo for approximately 30 days. At surgery, the cancers of the men in the lycopene group appeared to have regressed, while the cancers of those taking the placebo continued to grow. As yet, no follow-up has been reported. In Summary Definitive answers in the area of sex-hormone-related cancers, sex-hormone metabolites, testing for sex-hormone metabolites, and alteration of sex-hormone metabolism with diet and supplements are not yet available. However, as is often said in clinical preventive medicine, by the time definitive answers are available, many of us will no longer be living, so we must proceed on the best available evidence, knowledge of individual circumstances, and clinical judgement. It now appears that both enough evidence and enough tools are available for us to rationally undertake further steps in the prevention of sex-hormone-related cancers.


This article was adapted for reprint with permission.
Copyright ® 2000 Agora South, LLC.
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