Nutrition plays a crucial role in the prevention of chronic diseases, as most of them can be related to diet. Diet is an important factor in determining cancer incidence in many countries and regions. Diet can have both positive and negative effects on carcinogenesis. Dietary carcinogens represent 30 to 35% of cancer causes. Several substances in diet such as mycotoxins, heterocyclic amines, polycyclic aromatic hydrocarbons, N-nitroso compounds and acrylamide have been associated with increased risk of cancer. Diet also contains bioactive food components (BFC) which prevent cancer development. Their beneficial effects could be either maintenance or promotion of a state of well being or health and/or a reduction of cancer risk. Research on BFC continues to evolve albeit with shared challenges among scientists in the field of cancer treatment and prevention. Certain compounds such as phytochemicals and probiotics have cancer preventing properties. Awareness of the importance of consumption of functional foods or BFC as well as the importance of the whole diet rather than the isolated compounds as a cancer-preventive strategy for the general public should be promoted.