Epidemiological studies on the potential health effects of dietary polyamines are scarce. The present study aimed to estimate habitual intake of polyamines (putrescine, spermidine and spermine) and examine whether spermidine intake is inversely associated with all-cause and cause-specific mortality in a population-based cohort study in Japan. The study included 13 355 men and 15 724 women aged 35 years and older. Diet was assessed via a validated FFQ at the baseline in 1992. The intake of polyamines was estimated mainly using databases of polyamine content in foods consumed among Japanese population. Sex-specific hazard ratios (HR) and 95 % CI for all-cause and cause-specific mortality were estimated according to polyamine quartiles. During 16 years of follow-up, 2901 deaths in men and 2438 in women occurred. The intake of any polyamine was not significantly associated with all-cause or cause-specific mortality after controlling for covariates in men and women. There was a suggestive positive association between spermidine intake and cancer mortality in women: HR for the highest v. lowest quartile were 1·38 (95 % CI (0·99, 1·93); Ptrend = 0·02). Our results did not provide support for the notion that dietary spermidine has beneficial effects on mortality. Further studies on dietary polyamines and longevity, as well as the morbidity of specific diseases, including cancer, are needed across populations with different dietary habits.

Galactose and its metabolites, primarily derived from lactose, may have toxic effects on the ovary. We aimed to prospectively examine the associations of galactose and lactose intakes with the onset of natural menopause. The data of a population-based cohort study in a Japanese community (the Takayama study) initiated in 1992 were analysed, with follow-up data collected in 2002. Among the participants of the Takayama study, premenopausal women (n 3115) aged 35–56 years at baseline were included in this study. Dietary intake, including lactose and galactose was assessed only at baseline using a FFQ. The menopausal status and age at menopause were determined based on the participants’ self-reports, and natural menopause was defined as the absence of menstruation for 12 months or more. Cox proportional hazards models were used to estimate the hazard ratios (HR) and 95 % CI. A total of 1790 women experienced natural menopause within the 10-year follow-up. Lactose and galactose intakes were associated with a later onset of natural menopause after adjusting for potential confounding factors and the HR (95 % CI) for the highest v. lowest quartile were 0·80 (0·69, 0·92) (P-trend = 0·001) in lactose and 0·86 (0·74, 1·00) in galactose (P-trend = 0·036), respectively. High intakes of lactose and galactose were associated with a later onset of natural menopause. Despite the presumed ovotoxicity effects, lactose and galactose intakes at usual levels may not be deleterious to the ovarian aging process among Japanese community-dwelling women.

Numerous epidemiological studies have suggested that nut intake is associated with a reduced risk of mortality. Although diets and lifestyles differ by regions or races/ethnicities, few studies have investigated the associations among non-white, non-Western populations. We evaluated the associations of total nut and peanut intakes with all-cause and cause-specific mortality in a population-based prospective cohort in Japan. Participants (age: ≥35 years at baseline in 1992; n 31 552) were followed up until death or the end of follow-up in 2008. Those with cancer, CHD or stroke at baseline were excluded. Dietary intake was assessed only at baseline by using a validated FFQ. In total, 2901 men died during 183 299 person-years and 2438 women died during 227 054 person-years. The mean intakes of total nuts were 1·8 and 1·4 g/d in men and women, respectively. Although peanut intake accounted for approximately 80 % of the total nut intake, total nut and peanut intakes were inversely associated with all-cause mortality in men after adjusting for all potential confounders. For example, compared with the lowest quartile category, the adjusted hazard ratio (95 % CI) of total nut intake for all-cause mortality in men of the highest quartile category was 0·85 (95 % CI 0·75, 0·96) (Pfor trend = 0·034). Peanut intake was inversely associated with digestive disease mortality in men and CVD mortality in women. Total nut and peanut intakes, even in low amounts, were associated with a reduced risk of mortality particularly in men.

Studies on the intake of different types of carbohydrates and long-term mortality are sparse. We examined the association of starch, total and each type of sugar and free sugars with the risk of total and cause-specific mortality in a cohort of the general population in Japan. Study subjects were 29 079 residents from the Takayama Study, Japan, who responded to a self-administered questionnaire in 1992. Diet was assessed by a validated FFQ at the baseline. Mortality was ascertained during 16 years of follow-up. We noted 2901 deaths (974 cancer related and 775 cardiovascular related) in men and 2438 death (646 cancer related and 903 cardiovascular related) in women. In men, intake of starch was inversely associated with total mortality after controlling for covariates (hazard ratio (HR) for the highest quartile v. lowest quartile: 0·71; 95 % CI 0·60, 0·84; Ptrend < 0·001). Intakes of total sugars, glucose, fructose, sucrose, maltose and free and naturally occurring sugars were significantly positively associated with total mortality in men (HR for the highest v. lowest quartile of total sugar: 1·27; 95 % CI 1·12, 1·45; Ptrend < 0·0001). Similar relations were observed for cardiovascular mortality and non-cancer, non-cardiovascular mortality in men. In women, there was no significant association between any type of carbohydrates and mortality except that intake of free sugars was significantly positively associated with total and non-cancer, non-cardiovascular mortality. Data suggest that the high intake of starch reduces mortality, whereas the high intake of sugars, including glucose, fructose and sucrose, increases mortality in Japanese men.

Although higher circulating levels of oestrogen are related to postmenopausal breast cancer risk, limited information is available regarding effects of diet on endogenous oestrogen. Thus, we examined associations between macronutrient intakes and serum oestrogen with consideration of polymorphisms in oestrogen-metabolising genes. In this cross-sectional study, 784 naturally menopaused Japanese women aged 47–69 years were selected from participants of the Japan Multi-Institutional Collaborative Cohort Study. We documented dietary intakes, measured serum concentrations of oestrone (E1) and oestradiol (E2) and genotyped polymorphisms in oestrogen-metabolising CYP19A1 (rs4441215 and rs936306) and HSD17B1 (rs605059) genes. Trends and interactions were examined using linear regression models. In addition, we calculated the ratios of the oestrogen concentrations of the second to the highest quartiles (Q2–Q4) of dietary intake to those of the lowest quartiles (Q1). After adjustment for potential confounders, E2 was significantly associated with intake of carbohydrate and noodles; ratios of Q4 v. Q1 were 1·15 (95 % CI 1·04, 1·28) and 1·15 (95 % CI 1·04, 1·26), respectively. In contrast, E2 levels were inversely associated with intake of total energy, SFA and n-3 highly unsaturated fatty acids (n-3 HUFA); ratios of Q4 v. Q1 were 0·90 (95 % CI 0·82, 0·99), 0·89 (95 % CI 0·81, 0·98) and 0·91 (95 % CI 0·83, 1·00), respectively. In stratified analysis by polymorphisms, the rs605059 genotype of HSD17B1 significantly modified associations of E2 with intake of n-3 HUFA and fish; the associations were limited to those with the CC genotype. Macronutrient intakes were associated with serum E2 level, and these associations may be modified by HSD17B1 polymorphism in postmenopausal women.

Diets with a high glycaemic index (GI) or glycaemic load (GL) have been hypothesised to increase the risk of diabetes, CVD and some cancers. In the present study, the associations of dietary GI and GL with the risk of all-cause and cause-specific mortality were prospectively examined in a general population in Japan, where white rice is the main contributor of dietary GI and GL. A total of 28 356 residents of Takayama City, Japan, who responded to a self-administered questionnaire in 1992 were included in the present analyses. Dietary intake was assessed using a validated FFQ. Mortality was ascertained over 16 years. In men, dietary GI was found to be significantly inversely associated with the risk of all-cause and non-cancer, non-cardiovascular mortality; the hazard ratios (HR) for the highest v. lowest quartile were 0·80 (95 % CI 0·68, 0·95) and 0·64 (95 % CI 0·49, 0·84), respectively. Dietary GL was found to be significantly inversely associated with the risk of all-cause, cancer, and non-cancer, non-cardiovascular mortality; the HR for the highest v. lowest quartile were 0·71 (95 % CI 0·59, 0·86), 0·71 (95 % CI 0·52, 0·99) and 0·64 (95 % CI 0·48, 0·87), respectively. The results obtained for the GL derived from white rice, but not from other foods, closely mirrored those obtained for overall GL. In women, dietary GI was found to be significantly positively associated with the risk of cardiovascular mortality; the HR for the highest v. lowest quartile was 1·56 (95 % CI 1·15, 2·13). The results of the present study suggest potential favourable effects of dietary GI and GL on mortality in men, but an association between high GI and an increased risk of cardiovascular mortality in women.

Daily diet may have implications for skin ageing. However, data on the relationship between diet and the parameters of skin conditions are scarce. The present study aimed to examine the associations of biophysical properties of the skin of women with intakes of fats and antioxidant micronutrients as well as food groups as sources of these nutrients. In a cross-sectional study, we measured the hydration, surface lipids and elasticity of the skin of 716 Japanese women using non-invasive techniques. The extent of facial wrinkles in the crow's-foot area was determined by observation using the Daniell scale. Each subject's usual diet was determined with the use of a validated FFQ. After controlling for covariates including age, smoking status, BMI and lifetime sun exposure, the results showed that higher intakes of total fat, saturated fat and monounsaturated fat were significantly associated with increased skin elasticity. A higher intake of green and yellow vegetables was significantly associated with a decreased Daniell wrinkling score. Intake of saturated fat was significantly inversely associated with the Daniell wrinkling score after additional adjustment for green and yellow vegetable intake. Further studies with more accurate measurement methods are needed to investigate the role of daily diet in skin ageing.

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.

Certain dietary components which could affect oestrogen may have implications in the aetiology of uterine fibroids. We previously found that soya intake was inversely associated with a subsequent risk of hysterectomy, suggesting a potentially protective effect of soya against uterine fibroids, the major clinical indication for hysterectomy. We cross-sectionally assessed the associations of intakes of fat, soya foods, dietary fibre and alcohol with uterine fibroids. Study subjects were 285 premenopausal Japanese women participating in a health-check up programme, including gynaecological examinations, provided by a general hospital between October 2003 and March 2006. The presence of fibroids was confirmed by transvaginal sonogram. If women had undergone hysterectomy, self-report of fibroids was accepted. Each subject's usual diet, including alcohol, was determined with the use of a validated FFQ. Fifty-four women were identified as prevalent cases of fibroids or having had hysterectomy due to fibroids. The mean alcohol intake was statistically significantly higher among women with fibroids than among those without fibroids after controlling for known or suspected risk factors. For the highest compared with the lowest tertile of alcohol intake, the OR of uterine fibroids was 2·78 (95 % CI 1·25, 6·20). There was no significant association of intake of fats, soya isoflavones or dietary fibre with uterine fibroids. The data suggest that higher alcohol intake is associated with a higher prevalence of uterine fibroids. Further studies on diet, especially phyto-oestrogens, and uterine fibroids are needed given the limited data currently available.