In the post-Atkins world of nutrition and diet, protein has become one of the most misunderstood nutrients. Protein is broken down during digestion and later restructured to make the proteins and enzymes the body needs for life. Protein consists of amino acids, which are used in the construction of neurotransmitters, hormones, muscle, and other tissues. In this User's Guide, Dr. Keri Marshall demystifies protein and amino acids and explains how readers can use them to enhance their health.