Amazon informs me that I (for suitable interpretations of "I" in the context of buying something on my kindle) bought this in 2013. I finally read it, because it is this month's adult book group selection in Mayberry, NH (<-- not its real name).
As with _Stiff_ and _Spook_, I greatly enjoyed Roach's exploration of generally taboo territory. Her research is excellent, in areas that are not easily researched. This time, she is exploring the tube around which our lives entirely revolve: starting at the mouth and ending, er, at the other end, the alimentary canal is simultaneously central to our existence and the source of many of the most basic and transcendent joys of being alive -- and its activity is also hidden and misunderstood and abused. Not unlike the way products are created, used and then disposed of, we spend a lot more time at the beginning of the journey, and way too little at the end, to the detriment of, well, everything.
I was a little disappointed with parts of the flavor/taste discussion, but it was nonetheless very interesting, particularly the parts about animal palatants. After reading about how pet food is constructed, I had the chance to feed a new treat to a friend's dog when she came over for a visit. I had meant to buy the same treat I've been buying that dog for years now, but accidentally ordered a same flavor, same manufacturer, different form factor treat. I figured I'd cut it up a bit to reduce the size and give it a try. Watching P. contemplate the new option, chew it, walk around a bit, and then come back to eat the rest quite rapidly made sense after reading about how dogs react to food.
Perhaps the most riveting portion of the discussion was about Elvis, and the possibility that he was done in by a medical condition poorly understood then and only slightly better understood now, Hirschprung's disease (turns out there are nerves you don't know you have that if you don't have them, your world is so, so, so much worse).
Of course, the section on fecal transplants is still timely, and as Roach expected, we've come a fair ways in the years since this was written/published.
Roach spends a chunk of time on historic ideas about digestion that we no longer really entertain (autointoxication -- altho that actually still hangs around a bit on the fringes -- and reverse digestion, not to mention stomach frogs/snakes/etc.). I would love it if Roach were to write a book about people who fake medical problems through history and how they were caught then and now. We're starting to think of factitious disorder as a form of borderline personality disorder, and the whole area could do with the kind of research approach that Mary Roach excels at. She's unusual, in that she can forthrightly debunk, without losing basic compassion for the person engaging in the fraud; she seems to genuinely understand that the people faking the symptoms really do have an unaddressed problem -- it's just not stomach snakes or pooping out of the food hole. (The holy water enema as part of an exorcism bit, and the translator being quoted as saying nuns really should be allowed to have sex was particularly hilarious.)
If this is the kind of thing that sounds interesting to you, it's quite wonderful. I will note that there were parts I had difficulty reading while eating. I will also note that there are probably people who won't be able to eat for days after reading those parts (the description of the smell associated with emptying -ostomy bags in an airplane bathroom, for example, made me put the book down for a while), so, you know, plan accordingly.