There is a new book out called "Gut: The Inside Story of Our Body's Most Underrated Organ" by Giulia Enders:

https://en.m.wikipedia.org/wiki/Special:BookSources/97817716...

I can't recommend it enough as it is both entertaining and packed with comprehensive information on a taboo topic (hint: you are "the borg";)

Interview with Giulia Enders on "Gut":

http://youtu.be/weskzCKki-s