The exact reason of why eating dark chocolate has health benefits has been unclear. Maria Moore and John Finley, Louisiana State University, Baton Rouge, LA, USA, investigated the impact of human gut bacteria on three different types of cocoa powders, namely Iavado, Geekins Sienna, and Paragon. In a model digestive tract, comprised of a series of modified test tubes, digestion was simulated. Then the non-digestible materials were anaerobically fermented using human fecal bacteria.
Cocoa powder contains several polyphenolic, or antioxidant, compounds such as catechin and epicatechin, and a small amount of dietary fiber. Both components are poorly digested and absorbed. In the gut certain microbes, such as Bifidobacterium and lactic acid bacteria, ferment the fiber and metabolize the large polyphenolic polymers to smaller molecules, which are more easily absorbed. These smaller polymers exhibit anti-inflammatory activity. Moreover, this allows the population of these bacteria to grow, so that they can outperform other gut bacteria including some Clostridia and some Escherichia coli, which are associated with inflammation and can cause gas, bloating, diarrhea, and constipation.
The researchers recommend eating approx. 20–25 g cocoa powder per day and they say the health benefits can be increased when the fiber in cocoa is combined with prebiotics, carbohydrates found in foods that humans can’t digest, and solid fruits like pomegranates and acai.