Cocoa and Dark Chocolate Polyphenols: From Biology to Clinical Applications

Abstract

It is well known that cocoa and dark chocolate possess polyphenols as major constituents whose dietary consumption has been associated to beneficial effects. In fact, cocoa and dark chocolate polyphenols exert antioxidant and anti-inflammatory activities switching on some important signaling pathways such as toll-like receptor 4/nuclear factor κB/signal transducer and activator of transcription. In particular, cocoa polyphenols induce release of nitric oxide (NO) through activation of endothelial NO synthase which, in turn, accounts for vasodilation and cardioprotective effects. In the light of the above described properties, a number of clinical trials based on the consumption of cocoa and dark chocolate have been conducted in healthy subjects as well as in different categories of patients, such as those affected by cardiovascular, neurological, intestinal, and metabolic pathologies. Even if data are not always concordant, modifications of biomarkers of disease are frequently associated to improvement of clinical manifestations. Quite interestingly, following cocoa and dark chocolate ingestion, cocoa polyphenols also modulate intestinal microbiota, thus leading to the growth of bacteria that trigger a tolerogenic anti-inflammatory pathway in the host. Finally, many evidences encourage the consumption of cocoa and dark chocolate by aged people for the recovery of the neurovascular unit.

Keywords: anti-inflammatory activity; cocoa; dark chocolate; flavanols; nitric oxide; polyphenols; reactive oxygen species; transcription factors.

Figure 1

Major effects of cocoa and dark chocolate on the cardiovascular system. In response to cocoa and dark chocolate ingestion, a cascade of events takes place based on the nitric oxide (NO) and cyclic guanosine monophosphate (cGMP)-induced vasodilation and prostacyclin-mediated anti-inflammatory effects. Other details are contained in the text.

Figure 2

Cocoa flavanol-mediated brain effects. Release of brain-derived neurotrophic factor (BDNF) with increased neurogenesis and neurosurvival (left panel) and nitric oxide (NO)-mediated increase of cerebral blood flow (right panel) are the major effects exerted by cocoa flavanols. Further details are illustrated in the text.

Figure 3

Mechanisms of action of cocoa flavanols on obesity development. Increased expression of peroxisome proliferator-activated receptor (PPAR)-γ and adiponectin leads to reduction of lipid deposition and insulin resistance. Other details are present in the text.

Figure 4

The effects of coca-enriched diet on human microbiota. Cocoa diet modifies the intestinal microbiota, thus leading to a tolerogenic pathway with release of the anti-inflammatory cytokine interleukin (IL)-10. In the text, further details are illustrated.