Potential for preventive effects of cocoa and cocoa polyphenols in cancer

► Cocoa promotes changes in redox-sensitive signaling involved in cell functions. ► Cocoa prevents chronic inflammation and oxidative damage affecting carcinogenesis. ► Cocoa increases serum antioxidant status and apoptosis of cancer cells. ► Moderate cocoa or dark chocolate consumption may reduce cancer risks. Prevention of cancer through the diet is receiving increasing interest, and cocoa because of its polyphenolic compounds has become an important potential chemopreventive and therapeutic natural agent. Cocoa and its main polyphenols have been reported to interfere at the initiation, promotion and progression of cancer. Cocoa flavonoids have been demonstrated to influence several important biological functions in vitro and in vivo by their free radical scavenging ability or through the regulation of signal transduction pathways to stimulate apoptosis and to inhibit inflammation, cellular proliferation, apoptosis, angiogenesis and metastasis. Nevertheless, these molecular mechanisms of action are not completely characterized and many features remain to be elucidated. The aim of this review is to provide insights into the molecular basis of the potential chemopreventive activity of cocoa and its polyphenolic components by summarizing cell culture and animal models studies, as well as interventional and epidemiological studies on humans.