Everyone should read this book:

http://www.amazon.com/An-Apple-Day-Misconceptions-Truths/dp/1590513118/ref=sr_1_1?ie=UTF8&qid=1374762035&sr=8-1&keywords=books+schwarcz+apple+a+day

written by a Canadian PhD in Chemistry.  He is very proactive as to his own health, thus he studies things in great detail.  This is about as close as you'll get to the Owner's Manual for your body.  I've read a huge amount (from reputable sources, as well as occasional bunk) on these matters, and his representation of the current state of knowledge is excellent.  Not perfect (e.g., misplaced faith in CLAs --conjugated linoleic acids, for instance), but the best I've read on a very wide range of health topics.  It's an easy read for the layperson, and written in a lively, witty style.  Good fun.

Read it in health, my friends here on AgTalk.  Live long and prosper.