It's official: dark chocolate really is good for you (and now we know why)

While many of us cite the health benefits of dark chocolate as the reason for our addiction to the stuff, the exact reason for these health benefits has remained a mystery for many years - until now.

Researchers reported at the 247th National Meeting & Exposition of the American Chemical Society (ACS) that certain bacteria in the gut digest the chocolate and ferment it into anti-inflammatory compounds that are beneficial to the heart.

“We found that there are two kinds of microbes in the gut: the ‘good’ ones and the ‘bad’ ones,” said Maria Moore, an undergraduate student at Louisiana State University, who was a researcher on the study into dark chocolate.

“The good microbes, such as Bifidobacterium and lactic acid bacteria, feast on chocolate. When you eat dark chocolate, they grow and ferment it, producing compounds that are anti-inflammatory.”

Bad bacteria such as Clostridia and some E. coli are associated with inflammation and can cause gas, bloating, diarrhoea and constipation.

“When these compounds are absorbed by the body, they lessen the inflammation of cardiovascular tissue, reducing the long-term risk of stroke,” said John Finley, PhD, who led the study.

According to Finley, this study is the first to examine the effects of dark chocolate on the various types of bacteria in the stomach.

The research team tested three cocoa powders using a model digestive tract, which comprised a series of modified test tubes, to simulate digestion. They then subjected the non-digestible materials to anaerobic fermentation using human faecal bacteria.

Cocoa powder contains several polyphenolic - or antioxidant - compounds such as catechin and epicatechin, and a small amount of dietary fibre, Finley explained. Both compounds are poorly digested and absorbed, but when they reach the colon, the desirable microbes take over.

“In our study we found that the fibre is fermented and the large polyphenolic polymers are metabolised to smaller molecules, which are more easily absorbed. These smaller polymers exhibit anti-inflammatory activity,” Finley said.

Combining the fibre in cocoa with prebiotics is likely to improve a person’s overall health and help convert polyphenolics in the stomach into anti-inflammatory compounds.

“When you ingest prebiotics, the beneficial gut microbial population increases and outcompetes any undesirable microbes in the gut, like those that cause stomach problems,” Finley said.

According to Finley, people could experience even more health benefits when consuming dark chocolate combined with pomegranates and acai. Looking to the future, Finley says the next step is for industry to do just that.