Dietary factors including obesity and physical activity are estimated to account for approximately 35% of cancer death in the United States. According to the WHO/FAO report in 2003 based on a review of published epidemiological studies, convincing evidence between diet-related factors and cancer are available for the following associations: physical activity (colorectal cancer), overweight/obesity (cancers of esophagus < adenocarcinoma >, colorectum, breast < postmenopausal >, endometrium and kidney), alcohol (cancers of oral cavity, pharynx, esophagus, liver and breast), aflatoxin (liver) and Chinese-style salted fish (nasopharyngeal cancer). Fruits and vegetables (cancers of oral cavity, esophagus, stomach and colorectum) and physical activity (breast cancer) probably reduce the risk, while preserved and red meat (colorectal cancer), salt-preserved foods and high salt intake (stomach cancer) and very hot drinks and foods (cancers of oral cavity, pharynx and esophagus) probably increase the risk. Because these evidences are mainly based on epidemiological studies in Western countries, more evidence from the studies in Japan are essential to establish the appropriate recommendations for reducing the risk of developing cancer among Japanese.