This book explains the immune system's function and gives advice on how to strengthen it using food as your medicine. Dr. Fuhrman gives advice on supplements to avoid (many common ones like vitamin C) and supplements that are worth using (Zinc, Vitamin D and not much else) and teaches you how to get the nutrients and vitamins you need from common foods. A lot of the food suggestions are a bit much for most people but many recipes can be integrated gradually over time. Once you reap the rewards of a nutrient rich diet and learn the danger of eating the average western diet Dr. Fuhrman believes you won't look back. I enjoyed this book greatly and highly recommend to those with an interest in natural health and wellness.