I liked "SuperFoodsRX" and "SuperFoods HealthStyle" by Dr. Pratt.
"Eat, Drink, and Be Healthy" by Dr. Walter Willet (an oldie but goodie).
Most anything you read by Dr. Andrew Weil (visit his website for some info...http://www.drweil.com
). Same with Dr. Mercola (http://www.mercola.com/
)...even though both sell products, they have to make money some way (I don't buy any of their products, though I did try some of Dr. Weil's supplements previously)...but the info on their website is great.
Two books, "Skinny B*tch" and "The Engine 2 Diet", both vegetarian based (I'm not totally vegetarian).
I'm currently reading "The New Sonoma Diet" (Dr. Weil is a big fan of the Mediterranean way of eating and the Sonoma diet).
Also, Michael Pollan - http://michaelpollan.com/books/
- I've read "Food Rules", "In Defense of Food", and "The Omnivore's Dilemma".