Gulp: Adventures on the Alimentary Canal
Reviewed
Short Review: I have not liked any of Mary Roach's books as much as I liked Bonk. But I do enjoy her quirky writing style (she is the science equivalent to Sarah Vowell's history writing). Gulp is everything (and more) that you wanted to know about the digestive tract. Not as over the top disgusting as Stiff (about cadavers) but there were some places that were definitely more than I wanted to know.
My full review is on my blog at http://bookwi.se/gulp/