Editor’s Comment: This study demonstrates that even short-term changes in dietary habits can radically alter gut flora. After only two days of a meat-based diet, there was a decrease in the number of bacteria that normally help digest plant-based foods. There was also an increase in bacteria that have been linked to inflammatory bowel disease.
Diet rapidly and reproducibly alters the human gut microbiome
By Lawrence A. David et al.
The animal-based diet increased the abundance of bile-tolerant microorganisms (Alistipes, Bilophila and Bacteroides) and decreased the levels of Firmicutes that metabolize dietary plant polysaccharides (Roseburia, Eubacterium rectale and Ruminococcus bromii). Microbial activity mirrored differences between herbivorous and carnivorous mammals, reflecting trade-offs between carbohydrate and protein fermentation. Foodborne microbes from both diets transiently colonized the gut, including bacteria, fungi and even viruses.
Finally, increases in the abundance and activity of Bilophila wadsworthia on the animal-based diet support a link between dietary fat, bile acids and the outgrowth of microorganisms capable of triggering inflammatory bowel disease. In concert, these results demonstrate that the gut microbiome can rapidly respond to altered diet, potentially facilitating the diversity of human dietary lifestyles.