> especially vegetarian

Given that you have already made that choice, I'd recommend "How Not to Die" by Dr. Michael Greger. One of my biggest criticisms of Greger is that he is ignores any study that shows benefits of eating animals, even for specific conditions. People who would like to continue eating animals would find it easy to dismiss Greger for being so one-sided in what kinds of studies he cites. However, if you've already made the choice to prefer vegetarian, Greger's book (and videos) are an easy recommendation.