As new studies and observations constantly alter our understanding of how what we eat affects our bodies, tracking the evolving rules of good nutrition becomes ever more challenging.

For example, eight years ago, when Facts On File published the first edition of The New Complete Book of Food, it was commonly accepted that high-fiber diet could reduce the risk of colon cancer, beta-carotene, a yellow pigment in deep orange and dark green vegetables, would protect against cancer of the throat and lungs, fruit juice was healthful for kids—in fact, the more the better, and folic acid, a B vitamin, might lower the odds of suffering a second heart attack.