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Re: Sulforaphane Stimulates the Body's Cancer-Fighting Enzymes

Darrell Miller

5/13/05

Date: May 13, 2005 08:38 AM
Author: Darrell Miller (dm@vitanetonline.com)

Sulforaphane Stimulates the Body's Cancer-Fighting Enzymes

by Richard Conant, L.Ac, C.N.

The health benefits of vegetables were known historically, long before researchers began seeing a connection between vegetable consumption and cancer prevention. Over the last twenty years, evidence concerning this connection has steadily accumulated. The latest and most promising findings reveal that specific vegetable constituents—"phytochemicals" to use current scientific parlance— enhance the body's defenses against cancer.

This article will focus on one phytochemical in particular, a sulfur-containing compound called "sulforaphane." Found in Cruciferous vegetables such as broccoli, sulforaphane may prove to be one of our most powerful cancer prevention allies. Recent studies have shown that sulforaphane stimulates, or "induces," "Phase two enzymes." These enzymes are an integral part of the body's elaborate detoxification system that renders carcinogens inactive. This detoxification system turns carcinogens and other toxic substances into harmless molecules that are excreted from the body.

We need not fear carcinogens—the body is equipped to deal with them.

These findings, coupled with an appreciation of the body's ability to defend itself against carcinogens, have the potential to dramatically change the way we look at cancer and substances in the environment that "cause" cancer. We need to minimize unnecessary exposure to carcinogens, and the staggering quantity of hazardous chemicals in the environment remains an urgent health concern, for cancer and many other health problems. But, knowing the body is equipped with the means to defend itself against toxins, we do not need to fear carcinogens as perhaps we have in the past.

The natural world is full of carcinogens.

What's more, even if you eat 100 percent organic food and live in a environment free of toxic man-made chemicals, you are still being exposed to carcinogens every day of your life. Food is the primary route of this exposure. Plants, for their own defense, produce over 99% of all the pesticides in agricultural products.1 Almost all foods—in their natural state—contain tiny amounts of naturally-occurring, potentially carcinogenic chemicals.

The point is not to trivialize the concern over environmental toxins. The point is that the natural world is full of toxins that are not man-made. These substances have been around since before we appeared, which is why we have evolved with a highly efficient system for neutralizing them before they can damage our cells and initiate the complex process that produces cancer.

Broccoli sprouts are a concentrated source of cancer-fighting sulforaphane.

We cannot avoid carcinogens. What we can do is support our internal detoxification system. Sulforaphane is a powerful tool in this effort. We can start by following the often-repeated advice to eat a variety of vegetables every day, and include broccoli in our menu.

There is an even richer source of sulforaphane than broccoli itself. In September 1997, a group of scientists at the Johns Hopkins University School of Medicine made a breakthrough discovery— broccoli sprouts contain ten to one hundred times more sulforaphane than mature broccoli.2 Vegetable sprouts are generally regarded as exceptionally healthy foods. Broccoli sprouts now look like a shining star, especially when it comes to cancer prevention.

For those lacking the time or inclination to keep a fresh supply of broccoli sprouts on hand, broccoli spouts have been processed into an extract that is even more concentrated in sulforaphane. More on this later.

What have researchers learned about broccoli consumption and cancer rates?

More than 200 epidemiological studies—studies which track groups of people over time to uncover realtionships between variables such as diet and the incidence of disease—have invesitgated the connections between vegetable consumption and various forms of cancer.1 It should be understood that findings from epidemiological research are generally not regarded as conclusive; these studies are not controlled, and often use data gleaned from questionnaires, which are an imprecise method of gathering information. (In the case of diet questionnaires, for example, the study subjects may or may not record their food intakes with 100 percent accuracy.)

Epidemiological studies look for trends. To be credible, these trends need to show up consistently, in different population groups. Findings from the vegetable intake/cancer studies easily meet these criteria; the number of studies is large and the trend is consistent—vegetable consumption is strongly associated with a lower risk of developing cancer.

What about broccoli in particular? A paper published in the September 1996 issue of Cancer Epidemiology, Biomarkers & Prevention analyzes epidemiological data gathered from 94 studies concerning the cancer preventive effect of brassica vegetables.3 (The Brassica genus, part of the Cruciferae family, includes broccoli, cabbage, kale, cauliflower and brussels sprouts.) The data suggest that broccoli consumption reduces the risk of some of the most feared forms of cancer, including stomach and lung cancer.

Now, to put these data into a balanced perspective, the researchers point out that in most of the studies reviewed, brassica vegetable consumption was reported as part of the total vegetable intake. "In hardly any epidemiological studies was the effect of brassica vegetables separated from the effect of total vegetables or other vegetables by adjusting for consumption of these variables. Therefore, it is difficult to sort out whether the observed observation was attributable to brassica vegetables, to vegetables as a whole, or to other vegetables," they noted.

This uncertainty is a good example of why epidemiological studies alone do not give us open and shut conclusions. But the paper also adds that the apparent anti-cancer effect of brassica vegetables agrees with "the results of experimental studies in which brassica vegetables reduced mammary tumor incidence, hepatic tumor size, numbers of tumors per liver, tumor frequency, and the number of pulmonary metastases when given to rodents before or after a carcinogen insult."3

When you put together a plausible trend from epidemiological research with results of experimental studies that agree with the trend, and then add additional research that reveals the underlying mechanism for these observations, a clear picture begins to take shape. And, indeed, we now have a fairly good idea as to just how brassica vegetables, especially broccoli, help prevent cancer.

How sulforaphane helps prevent cancer from developing.

To see how sulforaphane works, let's look at a brief overview of the body's detoxification system.

The detoxification of carcinogens and other toxic substances takes place in the liver, and involves two distinct enzyme-driven processes or "phases". Phase one enzymes neutralize toxins by various routes. Some of these convert toxins into substances that are immediately eliminated. However, other Phase one steps convert toxins into intermediate products which are carcinogenic themselves, and require further treatment before they can be excreted. Phase two enzymes do this vital job. Phase two enzymes deactivate these carcinogenic metabolites of Phase one, and the final breakdown product is then eliminated once and for all. (For an excellent review of this subject, see Encyclopedia of Natural Medicine, by Drs. Michael Murray and Joseph Pizzorno.4)

Phase two is critical. If Phase one is in good working order, but Phase two is not, the potential threat from carcinogens increases. It is vitally important to keep Phase two operating well. This is where sulforaphane plays its cancer preventive role. Sulforaphane is a powerful inducer of Phase two enzymes.5,6

Broccoli sprouts-the ideal source of sulforaphane

Sulforaphane is one among a group of phytochemicals called "isothiocyanates." (These occur in brassica vegetables largely as "glucosinolates," which are precursors for isothiocyanates2,12 When the plant is crushed, glucosinolates are converted to isothiocyanates.) Sulforaphane induces Phase two enzymes exclusively, leaving Phase one enzymes alone. This means it helps reduce the load of carcinogenic Phase one intermediates without adding to the load by stimulating Phase one.8,9

As reported by the Johns Hopkins University research group, broccoli sprouts are an "exceptionally" rich source of sulforaphane (in the form of "glucoraphanin, sulforaphane's glucosinolate precursor). And broccoli sprouts have another advantage over mature broccoli. They contain almost no indole glucosinolates, phytochemicals present in mature broccoli that "can enhance tumorogenesis."2

Broccoli sprouts as an extract, now available as a dietary supplement, takes the concentration of sulforaphane to the next level. This recently developed nutraceutical product contains a potent 20 to 1 extract of three-day old fresh broccoli sprouts.

One 125 mg capsule supplies the same amount of sulforaphane as 125 grams, or about 5 ounces, of mature broccoli. Taking just one capsule a day is like eating two pounds of broccoli per week, which equals the intake of cruciferous vegetables believed necessary to obtain their health benefits.

References

1. Steinmetz, K.A. Potter, J.D. Vegetables, fruit, and cancer prevention: A review. J Am Diet Assoc. 1996;96:1027-1039.

2. Fahey, J.W., Zhang, Y., Talalay, P. Broccoli sprouts: An exceptionally rich source of inducers of enzymes that protect against chemical carcinogens. Proc. Natl. Acad. Sci. 1997; 94:10367-10372.

3. Verhoeven, D.T.H., et. al. Epidemiological studies on brassica vegetables and cancer risk. Cancer Epidemiology, Biomarkers & Prevention 1996;5:733-48.

4. Murray, M. Pizzorno, J. Encyclopedia of Natural Medicine. Rocklin, CA: Prima Publishing;1998:110-120.

5. Zhang, Y. Talalay, P, Cho, C., Posner, G.H. A major inducer of anticarcinogenic protective enzymes from broccoli: Isolation and elucidation of structure. Proc. Natl. Acad. Sci. 1992;89:2399-2403.

6. Gerhäuser, C. et. al. Cancer chemopreventive potential of sulforamate, a novel analogue of sulforaphane that induces phase 2 drug-metabolizing enzymes. Cancer Research 1997;57:272-78.

7. McDanell, R., McLean, A.E.M., Hanley, A.B., Heaney, R.K., Fenwick, G.R. Chemical and biological properties of indole glucosinolates (glucobrassicins): A review. Fd. Chem. Toxic. 1988;26(1):59-70.

8. Talalay, P. Mechanisms of induction of enzymes that protect against chemical carcinogenesis. in Advances in Enzyme Regulation, Vol. 28, Weber, G., Ed., 1989: Pergamon Press.

9. Prochaska, H.J. Santamaria, A.B., Talalay, P. Rapid detection of enzymes that protect against carcinogens. Proc. Natl. Acad. Sci. 1992;89:2394-98.

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