henry copeland:

Bread Affects Clinical Parameters and Induces Gut Microbiome-Associated Personal Glycemic Responses: Cell Metabolism

Several studies indicated that even short-term dietary interventions, whether animal-based, plant-based (David et al., 2014), or involving barley bread consumption (Kovatcheva-Datchary et al., 2015), result in significant, rapid, and reproducible alterations to the gut microbiome.
- www.cell.com