Well-being is received increased attention from people, researchers, and physicians. The main goal is to prevent the onset of pathologic health issues instead of using conventional pharmacological approaches unless absolutely necessary. Prevention and well-being are closely linked to the wrong lifestyle and dietary habits, which can determine the onset of illness. Some health conditions can be prevented and treated with the use of nutraceuticals in daily diet. Nutraceuticals are pharmacologically active substances that can be extracted from vegetable or animal products, and concentrated and administered in a suitable pharmaceutical form. A nutraceutical can provide beneficial health effects, e.g., the prevention and/or, in some cases, the treatment of disease. The key aspect is defining the range of possible uses for these new food-drugs and substantiation with in vitro and in vivo clinical data that support their efficacy, safety, and health benefits. This Special Issue is dedicated to assessing the sources, composition, formulation, use, experience in clinical use, mechanisms of action, and clinical data of nutraceuticals, which represent a new horizon for therapy and provide valuable tools to reduce the cost of the healthcare system, addressing resources for prevention rather than pharmacological therapy.