2.8. Interaction of Cocoa Polyphenols with Gut Microbiota: Potential Health Effects in Humans
Polyphenols present in cocoa and their health effects have been the subject of active research over the last 25 years. The physiological relevance of the clinical trials has, however, been rather limited due to the large inter-individual variability observed. The absorption of these phytochemicals in the gastrointestinal tract is limited and they reach the colon almost unaltered where they interact with the colon microbiota.
The colon microorganisms have a two-way relationship with cocoa polyphenols, as on the one hand these phytochemicals modulate the microbiota population, while on the other the microbiota transform polyphenols producing metabolites that differ from the original cocoa constituents.
Cocoa polyphenols activate the development of some bacterial groups while inhibiting the growth of others. This may be associated with some health benefits. Colonic microbes can metabolize cocoa proanthocyanidins, leading to metabolites that are better absorbed than the original compounds or can provide other health effects. Therefore, depending on the composition of the gut microbiome, the bioavailability and biological effects of cocoa polyphenols can be modulated.
The identification of the bacteria responsible for the metabolic transformation of specific phenolics is an active area of research, and members of the Coriobacteriaceae and different Lactobacilli and Bifidobacteria have been associated with specific metabolic transformations of proanthocyanidins in the gut. The mechanisms through which these microbiota metabolites exert their biological effects are currently being studied.
This means that individuals can produce, absorb and excrete different proanthocyanidin metabolites, and therefore enjoy different biological effects due to cocoa intake, depending on their microbiome, and this could partly explain the interindividual variability observed in human intervention studies with cocoa products.
This opens new opportunities for the development of cocoa-based nutraceuticals and functional foods. The discovery of the human enterotypes will eventually have future implications in nutritional and medicinal plant treatments and in the development of specific drugs and food products for individuals with a specific enterotype within the field of personalized nutrition.