The science journalist draws on ancient food traditions and the latest research on healthy gut maintenance to explain the role of the microbiome and how to adapt a diet to promote optimal microbiome balance.

Microbes: in our guts and under fire -- What's in the gut -- Feeding the microbiome -- Quintessential culture: dairy -- Consider the pickle: produce -- Intoxicating ferments: grains -- Basic beans: legumes and seeds -- The undead: meat -- Bringing it home -- Conclusion. saving an invisible world.