In Japan, the incidence of and mortality rate for prostate cancer are still low compared with those in Western countries, but they are increasing dramatically; in the past 30 years, the incidence and mortality rate have increased by 5.8-fold and 2.0-fold, respectively (Center for Cancer Control and Information Services, National Cancer Center, Japan). Factors that account for this increase are speculated to be several environmental factors, which are strongly suggested from a study of men immigrating from Japan to Hawaii or California.1,2 In a review by De Marzo et al., several contributors to prostate inflammation were enumerated including infectious agents, hormonal changes, physical trauma, urine reflux and dietary habits.76 Among these environmental factors, diet is the factor that has changed dramatically in Japan in these past 50 years. A traditional Japanese diet used to consist of rice served with meals high in soybean products and fish, and low in red meat. Within 50 years, the Japanese diet has completely changed. There has been a 4.5-fold increase in the intake of animal fat and a 4.0-fold increase in the intake of animal protein, whereas there was only a slight (1.1-fold) increase in total energy. If there is a factor in the diet that relates to the increase in prostate cancer in Japan, it might be something included in the animal products. There are several case–control and prospective studies that suggest a relationship between red meat consumption and prostate cancer risk. Wright et al. carried out a population-based prostate cancer case–control study comprising 1309 cases and 1267 controls, and found that red meat consumption was positively associated with prostate cancer risk (OR 1.43, 95% CI 1.11–1.84).77 A prospective study consisting of 65 548 men with a follow-up period of 11 years resulted in 5113 prostate cancer cases, and indicated that red meat consumption was significantly associated with a higher risk of prostate cancer among black men (RR 2.0, 95% CI 1.0–4.2), but not among white men.78 There is yet another prospective study comprising 175 343 USA men with a follow up of 9 years. There were 10 313 prostate cancer cases, and the authors noted that consumption of red meat was associated with elevated prostate cancer risk (hazard ratio 1.07, 95% CI 1.00–1.14). Furthermore, they found that intake of barbecued/grilled meat was also associated with elevated prostate cancer risk (hazard ratio 1.09, 95% CI 1.02–1.17).79 It is known that high-temperature cooking methods, such as grilling, barbecuing or pan-frying, produce multiple mutagens and carcinogens, such as HCA, polycyclic aromatic hydrocarbons and N-nitroso compounds, and thus, methods of cooking meat might relate to prostate cancer risk. From a population-based case–control study, John et al. reported that grilled and well-done meat is associated with increased risk of prostate cancer.80 There are three prospective studies indicating that meat cooked at high temperature is associated with increased risk of prostate cancer.81–83 Cross et al.81 and Koutros et al.82 further analyzed estimated intake of HCA and polycyclic aromatic hydrocarbons by using the National Cancer Institute's CHARRED database (http://charred.cancer.gov) and found that intake of HCA, such as PhIP, MeIQx and DiMeIQx is associated with increased risk of prostate cancer. Although there is one prospective study that could not find an association between specific HCA intake and prostate cancer,84 some HCA, such as PhIP and MeIQx, have been shown to cause prostate cancer in a rodent model,85–87 and they might have some role in the development of human prostate cancer.