Summary: Cocoa was originally cultivated by ancient societies in Central and South America, where it was consumed as a fermented beverage for medicinal and ceremonial purposes. Cocoa and chocolate, its fermented byproduct, are rich in flavanols—potent antioxidants associated with a reduced risk of cardiovascular disease and cancer. Two types of flavanols, called catechins and procyanidins, have been shown in experimental studies to reduce markers of inflammation and angiogenesis, two processes closely linked to cancer development. While more study is required, cocoa and chocolate have significant potential for chemoprevention as a dietary supplement.
Cocoa, the seed of the cocoa tree, is believed to have been cultivated over 3,000 years ago by native inhabitants of Central and Northern South America. These inhabitants prepared cocoa as a fermented beverage, similar to tea, which was used for medicinal and ceremonial purposes, and the beans themselves were used as a form of currency. Spanish explorers brought cocoa back to Spain in the early 1500s, and from there it spread to France, Italy, and eventually to Great Britain. In the middle of the 18th Century, chocolate manufacturing was introduced to Massachusetts using cocoa imported from the West Indies and Central America. Commercial chocolate become available in the mid-19th Century when a London company added sugar to chocolate liquor and cocoa butter.
Chocolate, the fermented byproduct from processed cocoa, contains high levels of bioactive flavanoids (polyphenols) that are formed during the fermentation process. Two flavanoids in particular, catechins and procyanidins, are highly concentrated in dark chocolate and cocoa powder. Observational studies indicate that catechins and procyanidins derived from green tea, red wine and soy may protect against a number of chronic diseases, notably cardiovascular disease and cancer.
The cancer-protecting (chemoprotective) activity of catechins and procyanidins is likely related to their ability to inhibit proliferation of cancer cells, remove toxins from the body, reduce inflammation, and suppress angiogenesis.
Angiogenesis, the process by which tumors acquire a blood supply, is a critical process in cancer development. Chronic inflammation is a known risk factor for both cardiovascular disease and many types of cancer. Inflammatory cells create an attractive environment for tumor growth, facilitate cell proliferation and angiogenesis, and promote genetic instability in cancer cells. Markers of inflammation, such as interleukin-2, C-reactive protein, and tumor necrosis factor-µ, have been associated with cancer risk in prospective studies.
Flavanols contained in green tea, soy and other foods have been shown to reduce markers of inflammation and suppress cancer cell proliferation in a number of experimental studies. Catechins and procyanidins inhibit the activation of NFkB, a key regulator of inflammation and the immune response. Relatively few studies have specifically looked at the influence of cocoa on markers of inflammation. However, since dark chocolate and cocoa contain very high concentrations of procyanidins—higher than most other foods—it is quite possible that chocolate may suppress inflammation to an extent equal to or greater than that of other foods. Cocoa has one of the highest concentrations of flavanoids of any food—over 10% of the total weight of cocoa powder.
Prospective studies using cocao as a nutritional supplement will help to better define the anti-inflammatory and chemopreventive potencies of cocoa powder and chocolate. The epidemiological evidence for chocolate is also less extensive than for green tea and other foods. Among two case-control studies that specifically looked at chocolate intake in relation to cancer risk, one found no association between chocolate consumption and colon cancer risk, while the other found a lower prevalence of pre-cancerous colon polyps with higher chocolate intake. Nonetheless, cocoa and chocolate, with its high flavanol content, have substantial potential for chemoprevention and should be studied further in well-designed trials using defined dietary amounts with valid markers of inflammation.
Originally posted on February 21, 2011 by eattodefeat by Roderick Smith, M.S.
Maskarinec G. Nutr and Cancer 2009;61(5):573-579.
Cancer Protective Properties of Cocoa: A Review of the Epidemiologic Evidence
Gertraud Maskarinec Cancer Research Center of Hawaii, Honolulu, Hawaii, USA
Due to their high concentration of catechins and procyanidins, bioactive compounds with distinct properties, cocoa and chocolate products may have beneficial health effects against oxidative stress and chronic inflammation, risk factors for cancer and other chronic diseases. This review focuses on the epidemiologic evidence for protective effects against cancer and overall mortality. The very small number of observational epidemiologic studies offers weak support for a reduction in mortality and little data related to cancer, whereas several intervention studies, despite their short duration, have reported some favorable changes in biomarkers assessing antioxidant status but very few findings related to inflammatory markers. In moderation, cocoa products may offer strong antioxidant effects in combination with a pleasurable eating experience. The benign profile of its fatty acids in combination with the low content of sugar of dark chocolate should lessen concerns about the adverse effects of cocoa products. Future nutritional trials need to assess a larger number of biomarkers that may be relevant for cancer risk, whereas epidemiologic studies require valid dietary assessment methods to examine the association of cocoa products with cancer risk in larger populations and to distinguish possible cancer protective effects of cocoa products from those due to other polyphenolic compounds.
Weisburger JH. Exp Bio Med 2001;226(10):891-897.
Chemopreventive Effects of Cocoa Polyphenols on Chronic Diseases
John H. Weisburger2
American Health Foundation, Valhalla, New York 10595
We have explored the causes of the major chronic diseases prevailing in the world and the relevant mechanisms as a sound basis for recommendations for their prevention. Research shows that the cocoa bean, and tasty products derived from the cocoa bean such as chocolate, and the beverage cocoa, popular with many people worldwide, is rich in specific antioxidants, with the basic structure of catechins and epicatechin, and especially the polymers procyanidins, polyphenols similar to those found in vegetables and tea. Metabolic epidemiological studies indicate that regular intake of such products increases the plasma level of antioxidants, a desirable attribute as a defense against reactive oxygen species (ROS). The antioxidants in cocoa can prevent the oxidation of LDL-cholesterol, related to the mechanism of protection in heart disease. Likewise, a few studies show that ROS associated with the carcinogenic processes is also inhibited, although there have not been many studies on a possible lower risk of various types of cancer either in humans or in animal models consuming cocoa butter or chocolates. Based on the knowledge acquired thus far, it would seem reasonable to suggest inhibition of the several phases of the complex processes leading to cancer, as a function of quantitative intake of antioxidants, including those from cocoa and chocolates. Cocoa and chocolate also contain fats from cocoa butter. These are mainly stearic triglycerides (C18:0) that are less well absorbed than other fats, and are excreted in the feces. Thus, cocoa butter is less bioavailable and has minimal effect on serum cholesterol.
Keywords: cocoa, chocolate, polyphenols, reactive oxygen species, carcinogens, genotoxic, epigenetic, fats, stearate, cancer, heart diseases