Nutraceuticals are commonly defined as a substance that may be considered a food or part of food that provides medical or health benefits, encompassing the prevention and treatment of disease. So far, a lot of emphases were put on nutraceuticals health benefits contrasting the little information available on their efficacy, side-effects or possible drug interactions. Within this context, this book aims to raise the consumers' awareness of nutraceuticals diversity, their potential health benefits, side effects, and drug interactions as well as current legislation. Therefore this publication aims to provide up-to-date information about the safe use of nutraceuticals in everyday life from a critical point of view. Also, their proven health benefits will be approached in relationship with the most common diseases, where they are used to prevent, treat or as a complementary therapy to classical medication. Because, the use of experimental models is a mandatory step for understanding the mechanisms of action and characteristic effects of nutraceuticals, the most relevant in vitro and in vivo studies that proved the beneficial effects of some of the most widespread nutraceuticals were described. Also, because of their high prevalence within the general population, the use of nutraceuticals in cardiovascular diseases, diabetes, respiratory and viral infections will be discussed. Special focus will be given to the use of nutraceuticals in the pediatric population. Also, their effect on dermatological conditions and neurological conditions will be addressed. Nutraceuticals may represent a valuable asset in medicine, but future research is required to establish their full therapeutic potential and to translate current findings into clinical practice.