Although the inverse association between coffee consumption and risk of diabetes has been reported numerous times, the role of caffeine intake in this association has remained unclear. We evaluated the consumption of coffee and other beverages and food containing caffeine in relation to the incidence of diabetes. The study participants were 5897 men and 7643 women in a community-based cohort in Takayama, Japan. Consumption of coffee, green tea, oolong tea, black tea and chocolate snacks were measured with a semi-quantitative FFQ in 1992. At the follow-up survey in 2002, the development of diabetes and the time of diagnosis were reported. To assess the association, age, smoking status, BMI, physical activity, education in years, alcohol consumption, total energy intake, fat intake and women's menopausal status were adjusted. Among men who consumed one cup per month to six cups per week and among those who consumed one cup per d or more, the associated hazard ratios were 0·69 (95 % CI 0·50, 0·97) and 0·69 (95 % CI 0·49, 0·98) compared with those who drank little to no coffee, with a P value for trend of 0·32. The hazard ratios for women with the same coffee consumption patterns were 1·08 (95 % CI 0·74, 1·60) and 0·70 (95 % CI 0·44, 1·12), with a P value for trend of 0·03. The association between estimated total caffeine intake and risk of diabetes was insignificant both among men and among women. The results imply that coffee consumption decreased the risk of developing diabetes. The protective effect may exist aside from the influence of caffeine intake.

Dietary supplementation with branched-chain amino acids (BCAAs), including leucine, isoleucine, and valine, has shown potential benefits for the metabolic profile. However, higher blood BCAA levels have been associated with insulin resistance. To our knowledge, there has been no study on dietary BCAAs and the risk of diabetes. We examined the association between BCAA intake and risk of diabetes in a population-based cohort study in Japan. A total of 13,525 residents of Takayama City, Japan, who enrolled in a cohort study in 1992 responded to a follow-up questionnaire seeking information about diabetes in 2002. Diet at baseline was assessed by means of a validated food frequency questionnaire. A high intake of BCAAs in terms of percentage of total protein was significantly associated with a decreased risk of diabetes in women after controlling for covariates; the hazard ratio for the highest tertile versus the lowest was 0.57 (95% confidence interval: 0.36, 0.90; P-trend = 0.02). In men, leucine intake was significantly marginally associated with the risk of diabetes; the hazard ratio for the highest tertile versus the lowest was 0.70 (95% confidence interval: 0.48, 1.02; P-trend = 0.06). Data suggest that a high intake of BCAAs may be associated with a decrease in the risk of diabetes.

BackgroundSeveral studies have reported the prevalence of tinnitus among general populations; however, most of these studies were conducted in Europe or the United States. We estimated the prevalence of tinnitus among the general adult population in Japan.MethodsThe subjects were participants in the Takayama Study, a population-based cohort study. In 2002, a total of 14 423 adults (6450 men and 7973 women) aged 45 to 79 years responded to a self-administered questionnaire that inquired about history of tinnitus, which was defined as episodes lasting longer than 5 minutes, excluding those occurring immediately after noise exposure. Respondents were also asked about the loudness and severity of tinnitus.ResultsOverall, 11.9% of the subjects reported having tinnitus; the percentage was somewhat higher among men (13.2%) than women (10.8%). The prevalence of tinnitus increased with age in both sexes. Approximately 0.4% of the overall population reported that tinnitus had a severe effect on their ability to lead a normal life. Medical history of hypertension or ischemic heart diseases, use of steroid or antihypertensive medication, and employment as a factory worker or machine operator were associated with tinnitus status in both men and women.ConclusionsTinnitus is relatively common in Japan. Although the use of various definitions of tinnitus in different studies makes it difficult to compare prevalence among populations, the present prevalence estimate was similar to those in studies in Europe and the United States.

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Data suggest that natto intake may contribute to the reduction of CVD mortality.