Ingestion of dark chocolate improves constipation and alters the intestinal microbiota in Japanese women

In a previous study, we found that proteins from cacao beans (cacao proteins) were resistant to digestive enzymes and that ingestion of the indigestible cacao proteins promoted defecation and altered the intestinal microbiota in mice. Therefore, we investigated whether ingestion of dark chocolate containing high amounts of cacao proteins improves constipation and alters the intestinal microbiota in Japanese women. Bowel movement frequency and stool amount after dark chocolate ingestion were significantly higher than before dark chocolate ingestion and significantly higher than after ingestion of white chocolate with no cacao proteins. Next, stool samples were collected, and the intestinal microbiota was analyzed by next-generation sequencing-based 16S rRNA. There was no significant difference in the α-diversity index of the gut microbiota between before and after ingestion of white chocolate, but the α-diversity index of the gut microbiota after ingestion of dark chocolate was significantly higher than before ingestion. The relative abundances of Faecalibacterium and Megamonas in the fecal microbiota after dark chocolate ingestion were significantly higher than before dark chocolate ingestion and significantly higher than after white chocolate ingestion. The relative abundances of Anaerostipes, Butyricicoccus, and Roseburia in the fecal microbiota after dark chocolate ingestion were significantly higher than before ingestion. Spearman correlation analysis revealed a correlation between the stool amount and relative abundances of Megamonas and Roseburia in the dark chocolate ingestion group. These results indicate that ingestion of dark chocolate improved constipation in humans and promoted increase of the relative abundances of butyrate producing bacteria such as Faecalibacterium, Megamonas, Anaerostipes, Butyricicoccus, and Roseburia in the intestinal microbiota.