Amazon maintains lists their best sellers in the Digestive Organ Diseases category.
However the two top selling books overall on gut microbes are written by David Perlmutter, they are:
- Grain Brain: The Surprising Truth about Wheat, Carbs, and Sugar–Your Brain’s Silent Killers
- Brain Maker: The Power of Gut Microbes to Heal and Protect Your Brain–for Life
Finally if you are looking for a gut health book written in your native european language, Julia Enders wins the award for european gut superstar.