Melissa Block, Jack Challem and

Jack Challem, the ''User's Guide'' Series Editor, is a leading American health writer and editor of ''The Nutrition Reporter'' newsletter. His scientific articles have appeared in ''Medical Hypotheses,'' ''Free Radical Biology and Medicine,'' and the ''Journal of the National Cancer Institute.''Melissa Block, E.Ed., is a health journalist and author who lives in Southern California. She has authored and contributed to dozens of books, articles, and websites on alternative medicine,nutrition, and fitness topics. She holds a graduate degree in exercise physiology from the University of Virginia.;