Chocolate: Potential Cancer Fighter

Chocolate: Potential Cancer Fighter
(Breast Cancer, Prostate Cancer, Gastrointestinal Cancer)

It's no secret that cancer, in its many forms, is one today's most feared diseases. And while progress has been made in the treatment of many cancers, there is still much to be learned regarding this insidious killer. In recent years, scientific research has uncovered the potential of chocolate's main constituents to fight cancer.

One study found that procyanidins were potent inhibitors of tyrosine kinase (ErbB2) expression, a molecule responsible for increasing blood vessels in a tumor, making the cancer grow faster. In simple words, cocoa procyanidins stop new blood vessels from forming, which in turn decreases the ability of cancer cells to grow. Numerous cancers like colon, breast, lung, ovarian, and prostate cancers are controlled in part by the ErbB2 molecule. The researchers found other receptor molecules that stimulate cancer cells were inhibited by the cocoa procyanidins.

They also found that flavanols inhibited reactive nitrogen species and formed nitrous derivatives, which inhibit cancer cell growth, especially gastrointestinal cancers.

Other research on the previously discussed Kuna Indians in Panama also suggests that cocoa and its principal ingredients can protect the body from cancer. For instance, researchers from the University of Panama recently demonstrated that cancer death rates among the Kuna are significantly less than those of mainland Panamanians (as are rates of cardiovascular disease and diabetes-related deaths). This is important because the Kuna consume far higher levels of cocoa than the rest of the world, and suggest that the low morbidity rates are due at least in part to increased intake of various polyphenols present in cocoa.

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Breast Cancer

Findings from a recent pre-clinical trial show that one of chocolate's procyanidins deactivates a number of proteins that likely work in concert to push cancer cells to continually divide. A research team from Georgetown University performed a variety of tests on breast cancer cells and 4 proteins that contribute to their division and growth. They discovered that after treating the cells with the procyanidin compound, all 4 proteins involved in the reproduction of the cancer cells were essentially "turned off," and the cancer cells stopped dividing. The lead researcher noted that the exciting aspect of their findings is that the procyanidin deactivated 4 separate regulatory proteins, greatly en-hancing its inhibitory effect. Many anti-cancer agents only display a single inhibitory effect. The results were published in a 2005 issue of Molecular Cancer Therapeutics.

Papers presented at the 2006 Annual Meeting of the American Association for Cancer Research showed that post-menopausal women who consumed higher levels of flavonoids had a 45 percent lower risk of breast cancer. Both flavones and flavanols showed this reduction. In the Harvard Nurses' Health Study, they found that women who consumed the most flavonoids had a 22 percent lower risk of ovarian cancer. They also noted that long-term intake was very important.

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Prostate Cancer

Researchers from France recently investigated the potential of cocoa polyphenols to thwart prostate cancer. The research team measured the inhibitory effect of cocoa polyphenol extracts (containing flavonoids, catechins and cyanidins) on two lines of human prostate cancer cells. Another line of prostate cells was treated with beta-sitosterol, a compound also attracting attention for its anti-cancer properties. The findings showed that the cocoa extract was very effective--even more so than the beta-sitosterol-at "completely inhibiting" the activity of metastatic and non- metastatic prostate cancer cells. On top of this, the findings suggested that even at the highest tested concentration, the polyphenols had no detrimental effect on healthy cancer cells. The promising results prompted the researchers to state that cocoa polyphenols "showed a strong and fast inhibition of cell growth."

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Gastrointestinal Cancer

Researchers from Weill Cornell Medical College, Strang Cancer Prevention Center and Brigham and Women's Hospital, discovered that certain catechins found in cocoa were able to restrict the growth of intestinal tumors in mice. The results were so promising (a reduction of up to 75% of new tumors among the mice subjects receiving the catechins) that the researchers noted that "the natural abundance and favorable bioavailability of catechin make it a promising addition to the list of potential colorectal cancer chemo-preventive agents."

Additional research, published in Free Radical Biology and Medicine, investigated the cell-protective abilities of procyanidins, another class of polyphenols found in cocoa. The researchers measured the anti-inflammatory and anti-cancer effects of cocoa procyanidins on GI cells that were artificially damaged, and found that the procyanidins were able to protect the cells from inflammation, increased permeability and other pre-cancerous mechanisms. The results showed again that cocoa polyphenols have the potential to protect the body's cells from turning cancerous, and can reduce the risk of various cancers.

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Science Spotlight: Cocoa and Cell Mutagenicity

Researchers from Hokkaido University in Japan recently found that exposing cancerous cells to cocoa and chocolate resulted in a substantial downturn in mutagenicity (cancer-causing activity) within cells. The researchers note that the protective effect was probably due to the polyphenols' ability to protect the cellular DNA.

Additional findings from scientists at the University of Minnesota indicate that cocoa polyphenols can moderate the activity of enzymes associated with cancer cell development.

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As discussed in the previous section on cell signaling, cocoa flavonoids can prevent cancer by several mechanisms:

• Stimulating phase II detoxification enzyme activity. Basically these are reactions that promote the excretion of toxic or cancer promoting chemicals.
• Preserving normal cell regulation. This helps keep the cells healthy and stops the damage of DNA which can contribute to development of cancer.
• Inhibiting proliferation and inducing apoptosis. Flavonoids help stop the cancer cells from growing rapidly and help the cancer cells die (apoptosis).
• Inhibiting tumor invasion and angiogenesis. Flavonoids prevent tumors from invading normal tissue by decreasing matrix-metalloproteinase enzymes and stopping blood vessels from growing fast (angiogenesis)
• Decreasing inflammation. By decreasing inflammation, it stops cell proliferation and helps the cancer cells die faster.
• Interfering with cell adhesion, cell spreading, and protease binding, stopping cells from growing.

Of course, we know that free radicals likely contribute to the development of different cancers. Cocoa flavonoids inhibit the inflammation that contributes to the formation of cancer. Many experts familiar with the research completed on chocolate are confident that its anti-oxidant capabilities are likely to help prevent the formation of cancerous cells.

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Chapter Summary Points

• While our understanding and treatment of cancer has progressed over the last decades, there is still much we don’t know, and cancer rates continue to rise.
• Cocoa flavonoids and other compounds have been shown to interfere with cancer via various mechanisms.
• Cancer rates among the Kuna Indians in Panama, who regularly consume chocolate in the form of a beverage, are significantly lower than Kuna who have moved to urban settings and adopted a more “modern” diet.
• Research shows cocoa may be effective at lower risk for various cancers, including breast, prostate, and gastrointestinal cancers.