Phytochemicals for Health presents the state of the art in the field of Phytochemicals. It highlights how, following the interactions of plants and the environment, an analytical approach for standardization and quality control is of fundamental importance to product quality control. Parts I and II cover the main problems relatied to natural products (plants, extraction, quantitative analysis, relationship with the surrounding environment). Part III presents the main classes of organic compounds identified and reported, and Part IV includes inorganic compounds. It also includes a chapter covering all the natural compounds that have become Active Principle Ingredients (API), highlighting next challenges. Phytochemicals for Health is a valuable tool for senior scientists working in natural products field interested in investigating the correlation between chemical profile and biological activity in order to obtain a product that is safe for human health.