Sweet Relief: Could Chocolate Prevent Cancer?

A prescription to eat more chocolate may sound like a fantasy, but it could become reality sometime in the future.

Studies show that eating chocolate may help reduce intestinal illnesses, including colon cancer, and could lower blood pressure and reduce inflammation, which may also protect against other types of cancer.

Cocoa, the raw material in chocolate, contains compounds called catechins and proanthocyanidins, members of a class of plant chemicals called flavanols, says Gertraud Maskarinec, MD, PhD, professor at the University of Hawaii Cancer Center. Catechins are also present in green tea, grapes and berries; proanthocyanidins in grapes, berries and red wine.

In a recent study published in Molecular Nutrition & Food Research, rats that were fed a cocoa-rich diet had significantly reduced numbers of markers for colon cancer. Researchers concluded that cocoa can stop cell-signaling pathways involved in tumor formation and seems capable of reducing oxidative stress.

In an earlier study at the Lombardi Comprehensive Cancer Center at Georgetown University, researchers used one type of proanthocyanidin on breast cancer cell cultures. The chemical appeared to deactivate a number of proteins that likely work to push a cancer cell to keep dividing.

These compounds, and those found in other plant foods, act as antioxidants, says Kathy Allen, a registered dietitian and director of nutrition at the H. Lee Moffitt Cancer Center and Research Institute in Tampa, Fla. Daily, normal (and essential) exposure to oxygen produces free radicals, which can cause cell damage and inflammation, which can be associated with cancer risk. Antioxidants help rid the body of free radicals and help cells repair themselves, possibly reducing the risk of cancer.

“Some plant chemicals are better at neutralizing free radicals, some are better at repairing cell damage and some at maintaining cell membranes,” says Allen. “So we need a variety of them, just as we need a variety of vitamins, because they have different functions.”

Exactly what these compounds do in the body is still under investigation. They may stimulate immune response, modulate detoxifying enzymes, regulate hormone metabolism, control programmed cell death or reduce abnormal cell proliferation.

Anti-inflammatory and antioxidant foods can potentially protect people from cancer at three stages, says David L. Katz, MD, director of the Yale-Griffin Prevention Research Center. First, they can lower the rate of mutation. Second, by preventing inflammation or excess of free radicals, antioxidants give our immune systems the upper hand in destroying abnormal cell lines that can result from mutations. Finally, these nutrients can help prevent those cell lines from becoming clinically detectable cancers, which can take years or even decades.

Exactly what these compounds do in the body is still under investigation, Maskarinec says. They may stimulate immune response, modulate detoxifying enzymes, regulate hormone metabolism, control programmed cell death or reduce abnormal cell proliferation. Catechins specifically may stimulate changes in pathways involved in gene expression and can protect nerves from injury.

Dark chocolate and cocoa powder are foods closest to the pure plant form of cocoa, Allen says. Three ounces of dark chocolate contains about 43 to 63 milligrams of flavanols. Processing and adding ingredients can greatly affect the amount of beneficial compounds present in a food. For example, milk chocolate has sugar, milk and other additives, so it has lower concentrations of chocolate’s beneficial compounds.

More research is needed to determine how much cocoa should be consumed for protective benefits without undesirable side effects, such as weight gain. Once that happens, those prescriptions might not be far behind.