The short review: This book aims to improve your mood mainly be making changes in your diet, particularly by recommending specific amino acids.
The longer review: The book begins by having the reader distinguish between false moods and true emotions by having them complete a questionnaire. By doing this, you can see which false mood type (or types) you seem to fit. From there, you are directed to certain chapters for a more individualized treatment. Action steps at the end of chapters tell you exactly what to do.
All-in-all it's certainly a valuable resource with much information. Know that it aims to primarily improve moods through nutritional means, which is a much overlooked area in my opinion, and anyone struggling with chronic bad moods is encouraged to check it out. Other books I liked that also take a natural approach include Exercise Beats Depression