Cancer is a leading cause of death worldwide. Although genetics certainly plays an important role, environmental factors -i.e., overall lifestyle, including diet, physical activity, and nutritional status, among others- are known to be triggering factors for the development of many types of cancer. Different dietary components have been associated with the risk of developing cancer; these include alcohol, red (processed) meat, and low-fiber diets. On the contrary, physical activity and the practice of frequent exercise, together with an energetically-restrictive dietary regimen appear to reduce the risk of neoplastic diseases. Moreover, specific substances within food have been considered to exert biologically active properties and thus have been considered as attractive candidates to be used not as a sole approach but -maybe- as coadjuvant agents during cancer therapy. Such nutraceuticals include: antioxidants, sulphoraphane, omega-3 fatty acids, lycopene, and polyphenols, among other. Even though preclinical and small clinical trials have shown promising evidence, it is still inconclusive, hence no actual dosage recommendations can yet be emitted. These open an interesting and urgent research field within Nutrition and Oncology.