Diet, obesity, and metabolic syndrome are very much linked to various cancers and may account for as much as 30–35% of cancer deaths, indicating that a reasonably good fraction of cancer deaths can be prevented by modifying the diet. Extensive research has revealed that a diet consisting of fruits, vegetables, spices, and grains has the potential to prevent cancer (Fig. 8). The specific substances in these dietary foods that are responsible for preventing cancer and the mechanisms by which they achieve this have also been examined extensively. Various phytochemicals have been identified in fruits, vegetables, spices, and grains that exhibit chemopreventive potential (Fig. 9), and numerous studies have shown that a proper diet can help protect against cancer (46, 67–69). Below is a description of selected dietary agents and diet-derived phytochemicals that have been studied extensively to determine their role in cancer prevention.