We prospectively examined the association between low-carbohydrate diet (LCD) score and incidence of type 2 diabetes (T2D) in Japanese adults using Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC Study) data. A total of 19 084 (7052 men and 12 032 women) Japanese non-diabetic participants aged 40–79 years, who enrolled in the JACC study between 1988 and 1990, were included in our analysis. Dietary intake was evaluated using a validated food-frequency questionnaire. The overall, animal and vegetable LCD scores were calculated by dividing the study participants into eleven categories based on the percentages of energy from carbohydrates, protein and fat. The incidence of T2D was assessed using a self-administered questionnaire. We used multivariable logistic regression analysis to estimate the odds ratios (ORs) and 95 % confidence intervals (CIs) of incident T2D across the quintile of each LCD score, with adjustment for potential confounders. During the 5-year study period, 490 adults (247 men and 243 women) developed T2D. The multivariable-adjusted OR of incident T2D for the highest v. lowest quintiles of overall and animal LCD scores, respectively, were 0·64 (95 % CI 0·42, 0·99) and 0·83 (95 % CI 0·55, 1·27) for men, 0·78 (95 % CI 0·51, 1·18) and 0·84 (95 % CI 0·57, 1·24) for women. The vegetable LCD score was associated with a lower risk of T2D in men (OR 0·51; 95 % CI 0·33, 0·77). Our results suggest that diets lower in carbohydrates and higher in fat and protein are unlikely to higher the T2D risk among Japanese individuals.

Reducing Na intake is an urgent global challenge, especially in East Asia and high-income Asia-Pacific regions. However, the sources of Na and their effects on urinary Na excretion have not been fully studied. We sought to clarify these sources and their association with urinary Na excretion. We examined four 3-d weighed food records and five 24-h urinary collections from each of 253 participants in Japan, aged 35–80 years, between 2012 and 2013. We compared the levels of Na according to four categories: foods contributing to discretionary or non-discretionary Na intake, the situation in which dishes were cooked and consumed, food groups and types of cuisine. We also conducted regression analysis in which 24-h urinary Na excretion was a dependent variable and the amounts of food intake in the four categories were independent variables. Levels of Na were the highest in discretionary intake (60·6 %) and in home-prepared dishes (84·0 %). Of the food groups, miso soup showed the highest percentage contribution to Na intake (13·3 %) after seasonings such as soya sauce. In the regression analysis, the standardised coefficient for foods of non-discretionary Na sources was larger than that for discretionary sources, whereas that for home-prepared dishes was consistent with the levels of Na in those foods. Pickled products, followed by fresh fish and shellfish, miso soup and rice, were associated with high urinary Na excretion. Thus, discretionary foods (such as miso soup) contribute the most to Na consumption, although non-discretionary intake (such as pickled vegetables) may influence urinary Na excretion.

The evidence on the association between B vitamins and the risk of CVD is inconclusive. We aimed to examine the association of dietary vitamins B1 and B3 intakes with risk of CVD mortality among 58 302 Japanese men and women aged 40-79 years participated in the Japan Collaborative Cohort (JACC) study. The Cox proportional hazard model estimated the hazard ratios (HR) and 95% CI of CVD mortality across increasing energy-adjusted quintiles of dietary vitamins B1 and B3 intakes. During 960 225 person-years of follow-up, we documented a total of 3371 CVD deaths. After adjustment for age, sex, and other CVD risk factors, HR of mortality from ischemic heart disease, myocardial infarction, and heart failure in the highest v. lowest vitamin B1 intake quintiles were 0.57 (95 % CI 0·40, 0·80; Pfor trend < 0·01), 0.56 (95 % CI 0·37, 0·82; Pfor trend < 0·01), and 0.65 (95 % CI 0·45, 0·96; Pfor trend = 0·13). The multivariable HR of myocardial infarction mortality in the highest v. lowest vitamin B3 intake quintiles was 0.66 (95 % CI 0·48, 0·90; Pfor trend = 0·02). Atendency towards a reduced risk of haemorrhagic stroke mortality was observed with a higher dietary intake of vitamin B3 (HR: 0·74 (95 % CI 0·55, 1·01)) but not vitamin B1. In conclusion, higher dietary intakes of vitamins B1 and B3 were inversely associated with mortality from ischemic heart disease and a higher dietary intake of vitamin B1 was inversely associated with a reduced risk of mortality from heart failure among Japanese men and women.

Dairy product intake was suggested to reduce the risk of gastrointestinal cancers. This study investigated the association between dairy product intake and the risk of pancreatic cancer (PAC) using a prospective cohort study and meta-analysis of prospective cohort studies. First, we included 59 774 people aged 40–79 years from the Japan Collaborative Cohort Study (JACC Study). The Cox regression was used to compute the hazard ratios (HR) and 95 % CI of incident PAC for individuals who reported the highest intakes of milk, cheese and yogurt compared with not consuming the corresponding dairy products. Then, we combined our results with those from other four prospective cohort studies that were eligible after searching several databases, in a meta-analysis, using the fixed-effects model before evaluating publication bias and heterogeneity across studies. In the JACC Study, the highest v. no intakes of milk, cheese and yogurt were not associated with the reduced risk of PAC after a median follow-up of 13·4 years: HR (95 % CI) = 0·93 (0·64, 1·33), 0·91 (0·51, 1·62) and 0·68 (0·38, 1·21), respectively. The results did not significantly change in the meta-analysis: 0·95 (0·82, 1·11) for milk, 1·16 (0·87, 1·55) for cheese and 0·91 (0·79, 1·05) for yogurt. The meta-analysis showed no signs of publication bias or heterogeneity across studies. To conclude, consumption of milk, cheese and yogurt was not associated with the risk of PAC either in the JACC Study or the meta-analysis.

The association between the intake of non-alcoholic beverages and CVD in Asians is uncertain. The intake of non-alcoholic beverages was estimated in 77 407 participants of the Japan Public Health Centre-based cohort study aged 45–74 years. The Cox regression calculated the hazard ratios (HR) and 95 % CI for incident CVD according to sex-specific quintiles of intake of non-alcoholic beverages. A total of 4578 incident CVD (3751 strokes and 827 CHD) were diagnosed during a 13·6-year median follow-up. The risks of stroke and total CVD were lower for the highest v. lowest intake quintiles of non-alcoholic beverages in men and women: the multivariable HRs (95 % CIs) were 0·82 (0·71, 0·93, Ptrend = 0·005) and 0·86 (0·76, 0·97, Ptrend = 0·02), respectively, in men and were 0·73 (0·63, 0·86, Ptrend = 0·003) and 0·75 (0·65, 0·87, Ptrend = 0·005), respectively, in women. The reduced risk was evident for both ischaemic and haemorrhagic strokes and was mainly attributable to green tea consumption. The intake of non-alcoholic beverages from coffee and other beverages was not associated with the risk of CVD in both men and women. Also, there was no association between the intake of non-alcoholic beverages and the risk of CHD in either sex. In conclusion, the risks of stroke and total CVD were lower with a higher intake of non-alcoholic beverages in Japanese men and women.

We sought to examine the prospective associations of specific fruit consumption, in particular flavonoid-rich fruit (FRF) consumption, with the risk of stroke and subtypes of stroke in a Japanese population. A study followed a total of 39 843 men and 47 334 women aged 44–76 years, and free of CVD, diabetes and cancer at baseline since 1995 and 1998 to the end of 2009 and 2012, respectively. Data on total and specific FRF consumption for each participant were obtained using a self-administrated FFQ. The hazard ratios (HR) of stroke in relation to total and specific FRF consumption were estimated through Cox proportional hazards regression models. During a median follow-up of 13·1 years, 4091 incident stroke cases (2557 cerebral infarctions and 1516 haemorrhagic strokes) were documented. After adjustment for age, BMI, study area, lifestyles, dietary factors and other risk factors, it was found that total FRF consumption was associated with a significantly lower risk of stroke in women (HR = 0·70; 95 % CI 0·58, 0·84), while the association in men was not significant (HR = 0·93; 95 % CI 0·79, 1·09). As for specific FRF, consumptions of citrus fruits, strawberries and grapes were found associated with a lower stroke risk in women. Higher consumptions of FRF, in particular citrus fruits, strawberries and grapes, were associated with a lower risk of developing stroke in Japanese women.

To examine the associations of salt perception with salt intake and blood pressure levels in general populations, we performed a cross-sectional study in two communities where salt intake level is different, Akita and Osaka in Japan. Taste perception (detection for certain taste and recognition for salt taste) was determined using a Na-impregnated test strip for 1024 Akita and 1199 Osaka adults aged 30–74 years. The proportions of detection for 0·1 % salt were 61, 62, 79, and 79 % in Akita men, Osaka men, Akita women and Osaka women, respectively. The corresponding proportions of not recognising of 1·6 % salt taste (>1·6 %) were 34, 30, 16 and 21 %. Detection threshold was higher in Akita than in Osaka for women aged 60–74 years, and recognition threshold was lower in Akita than in Osaka for women aged 30–59 and 60–74 years. The high detection (≥0·4 %) and recognition (>1·6 %) thresholds of salt taste were associated with higher salt intake scores for Akita men aged 30–59 years, whose detection and recognition thresholds tended be positively associated with systolic and diastolic blood pressures (SBP and DBP) after adjustment for potential confounders. Among Akita elderly men, detection threshold tended to be positively associated with SBP and DBP, while among Akita middle-aged women, recognition threshold was associated with SBP. In conclusion, the high thresholds of salt perception were inversely associated with salt intake for Akita middle-aged men and with blood pressure levels for Akita middle-aged and elderly men and middle-aged women.

Although the association between fruit consumption and CHD risk has been well studied, few studies have focused on flavonoid-rich fruits (FRF), in particular strawberries and grapes. We aimed to verify the association of total and specific FRF consumption with risk of CHD by a large prospective cohort study. A total of 87 177 men and women aged 44–75 years who were free of CVD and cancer at study baseline were eligible for the present analysis. FRF consumption was assessed using a FFQ. Cox proportional hazards regression models were used to estimate the hazard ratios (HR) of CHD in relation to FRF consumption with adjustment for potential risk factors and confounders. During a mean follow-up of 13·2 years, we identified 1156 incident CHD cases. After full adjustment for covariates including demographics, lifestyles and dietary factors, the HR were 0·93 (95 % CI 0·77, 1·11), 0·91 (95 % CI 0·75, 1·11), 0·84 (95 % CI 0·67, 1·04) and 0·78 (95 % CI 0·62, 0·99) for the second, third, fourth and fifth quintiles compared with the lowest quintile of FRF consumption. Regarding specific fruits, we observed a significant inverse association for citrus fruit consumption and a borderline inverse association for strawberry consumption, while no association was observed for apple/pear or grape consumption. Although the associations appeared to be stronger in women, they were not significantly modified by sex. Higher consumption of FRF, in particular, citrus fruits, may be associated with a lower risk of developing CHD.

Maternal diet during pregnancy can influence fetal growth; however, the available evidence is controversial. We aimed to assess whether maternal diet of Japanese women in mid-pregnancy can affect their offspring’s birth size via collection of questionnaire and medical record data. The studied sample was a large cohort of paired mothers and their singleton offspring (n 78 793) from fifteen areas all over Japan who participated in the Japan Environment and Children’s Study. The mid-pregnancy intakes of total energy, macronutrients and vitamins were lower than the recommended intakes for pregnant Japanese women. Maternal total energy intake was positively associated with the offspring’s birth weight; there was a 10-g mean difference in the offspring’s birth weight of mothers in the lowest (3026 g) v. highest (3036 g) quartiles of energy intake. Carbohydrate intake was positively associated with the offspring’s birth length (mean difference of 0·7 cm) and inversely associated with the ponderal index (mean difference of 0·8 g/cm3). Offspring of mothers in the highest v. lowest quartiles of total dietary fibre intake were on average 9 g heavier and had 0·3 cm longer birth length and 0·2 cm longer head circumference. The highest in reference to lowest intake quartile of vitamin C was associated with 13 g and 0·7 cm mean differences in the offspring’s birth weight and length, respectively. Several other associations were evident for maternal intakes of vitamins and the offspring’s birth size. In conclusion, maternal dietary intakes of energy, dietary fibre, carbohydrate and vitamins during pregnancy were associated with the offspring’s birth size.

The association of chocolate consumption with risk of gestational diabetes has not been examined. We aimed to investigate the prospective association between chocolate consumption and risk of gestational diabetes in a large birth cohort in Japan. A total of 97 454 pregnant women with a median gestational age of 12 weeks were recruited from January 2011 to March 2014. Data on demographic information, disease history, socio-economic status, lifestyle and dietary habits were obtained at the study enrolment. Dietary intake during the past 12 months before study enrolment was assessed through a semi-quantitative FFQ. The logistic regression was used to obtain the OR of gestational diabetes in relation to chocolate consumption. Among 84 948 women eligible for the analysis, 1904 cases of gestational diabetes (2·2 %) were identified during the period of pregnancy. After controlling for potential confounding factors including age, smoking status, drinking status, education level, occupation, pre-pregnant BMI, depression, previous history of macrosomia babies, parity, physical activity and dietary factors, women in the highest quartile of chocolate consumption, compared with those in the lowest quartile, had a significantly lower risk of developing gestational diabetes (OR 0·78, 95 % CI 0·67, 0·90; P for trend = 0·002). Stratified analyses suggested that the association was not significantly modified by pre-pregnancy BMI, age, parity, smoking status or drinking status. The present prospective cohort study provided evidence that chocolate consumption was associated with a significant lower risk of gestational diabetes in Japanese women.

Recent studies have shown that micronutrients are involved in the pathology of type 2 diabetes. Antioxidant effects of vitamins C and B2 and homocysteine-lowering effects of vitamins B6, folate and B12 may have protective roles. However, a few reports have investigated the association between dietary water-soluble vitamin intakes and risk of diabetes. In a prospective study encompassing 19 168 healthy Japanese men and women aged 40–79 years, we examined the associations between dietary intakes of water-soluble vitamins, determined by a validated self-administered FFQ, with the risk of 5-year cumulative incidence of type 2 diabetes by using the logistic regression model. Within the 5-year period, there were 494 self-reported new cases of diabetes. Higher dietary intakes of vitamins C, B2 and folate were associated with lower risk of incident diabetes only in women, whereas no associations of dietary intakes of vitamins B1, B3, B5, B6 and B12 were observed in either sex. The multivariable OR in the highest v. the lowest quartile of intakes among women were 0·61 (95 % CI 0·44, 0·94; P-trend = 0·04) for vitamin C, 0·56 (95 % CI 0·34, 0·93; P-trend = 0·03) for vitamin B2 and 0·70 (95 % CI 0·46, 0·98; P-trend = 0·03) for folate. Other than that for sex (P < 0·05), the P-interactions with age, BMI, smoking status or having a family history of diabetes were >0·10. In conclusion, higher dietary intakes of vitamins C, B2 and folate, but not other water-soluble vitamins, were associated with reduced risk of type 2 diabetes in Japanese women.

The role of fat-soluble vitamins in the pathology of type 2 diabetes needs further research. Possible protective effects could be expected for vitamins A and E via their antioxidant properties, vitamin K via its modulating effects on cytokines and insulin resistance and vitamin D via the enhancement of insulin sensitivity. However, the evidence on association between fat-soluble vitamins from diet and risk of diabetes is limited. Therefore, among 19 168 healthy Japanese of both sexes aged 40–79 years, we used the logistic regression analyses to examine the prospective association between FFQ-estimated dietary fat-soluble vitamins (A, K, E and D) and the risk of type 2 diabetes incident over a 5-year period. During this 5-year period, 494 new cases of diabetes were self-reported. Vitamins K and E from diet were associated with lowered risk of incident diabetes, whereas no associations with dietary intake of vitamin A or D were observed. The multivariable OR in the highest v. lowest quartiles of intakes were 0·71 (95 % CI 0·54, 0·93, Ptrend=0·01) for vitamin K and 0·72 (95 % CI 0·55, 0·95, Ptrend=0·02) for vitamin E. Mutual adjustment for dietary intake of these vitamins did not change the association. There were no interactions with sex, age, smoking status, BMI or having a family history of diabetes, P were >0·10. In conclusion, higher dietary intake of fat-soluble vitamins K and E, but not vitamin A or D, were associated with lowered risk of type 2 diabetes among Japanese population.

Few studies have reported the association between the Japanese diet as food score and mortality. This study aimed to investigate adherence to the Japanese food score associated with all-cause, CVD and cancer mortality. A total of 58 767 (23 162 men and 34 232 women) Japanese participants aged 40–79 years, who enrolled in the Japan Collaborative Cohort Study between 1988 and 1990, were included. The Japanese food score was derived from the components of seven food groups (beans and bean products, fresh fishes, vegetables, Japanese pickles, fungi, seaweeds and fruits) based on the FFQ. The total score ranged from 0 to 7, and participants were divided into five categories based on scores (0–2, 3, 4, 5 and 6–7). Hazard ratios (HR) and 95 % CI for all-cause, CVD and cancer mortality based on sex were estimated using Cox proportional models. During the follow-up period until 2009, 11 692 participants with all-cause, 3408 with CVD and 4247 with cancer died. The multivariable HR in the 6–7 and 0–2 Japanese food score groups were 0·93 (95 % CI 0·86, 1·01) in men and 0·82 (95 % CI 0·75, 0·90) in women for all-cause mortality and 0·89 (95 % CI 0·76, 1·04) in men and 0·66 (95 % CI 0·56, 0·77) in women for CVD mortality. Our findings suggest that adherence to the Japanese food score consisting of food combinations characterised by a Japanese diet may help in preventing all-cause and CVD mortality, especially in women.

To examine the association of plant-based food intakes with CVD and total mortality among Japanese. In the Japan Collaborative Cohort Study for Evaluation of Cancer Risk, 25 206 men and 34 279 women aged 40–79 years, whose fruit, vegetable and bean intakes were assessed by questionnaire at baseline in 1988–90, were followed for 13 years. Deaths from total stroke, stroke subtypes, CHD and total CVD, according to the International Classification for Diseases 10th Revision, were registered. During 756 054 person-years of follow-up, there were 559 deaths from total stroke, 258 from CHD, 1207 from total CVD and 4514 from total mortality for men, and for women, 494, 194, 1036 and 3092, respectively. Fruit intake was inversely associated with mortality from total stroke (the multivariable hazard ratio (HR (95 % CI)) in the highest v. lowest quartiles = 0·67 (0·55, 0·81)), total CVD (HR = 0·75 (0·66, 0·85)) and total mortality (HR = 0·86 (0·80, 0·92)). Vegetable intake was inversely associated with total CVD (HR = 0·88 (0·78, 0·99)). Bean intake was inversely associated with other CVD (HR = 0·79 (0·64, 0·98)), total CVD (HR = 0·84 (0·74, 0·95)) and total mortality (HR = 0·90 (0·84, 0·96)). Further adjustment for other plant-based foods did not alter the association of fruit intake with mortality from total stroke, total CVD and total mortality, but attenuated the associations of vegetables and beans with mortality risk. In conclusion, intakes of plant-based foods, particularly fruit intake, were associated with reduced mortality from CVD and all causes among Japanese men and women.

Limited egg consumption is often recommended to reduce serum cholesterol concentration for the prevention of CHD. We examined the association of egg consumption and total cholesterol concentration with the risk of CHD. A total of 90 735 subjects (19 856 men and 21 408 women, aged 40–59 years in cohort I; 23 463 men and 26 008 women, aged 40–69 years in cohort II) were followed from 1990–4 to the end of 2001 under the Japan Public Health Center-based prospective study. Total cholesterol was obtained in 36 % of the subjects. Men and women were combined for the analyses. The subjects were categorised into four groups according to egg consumption. Subjects with total cholesterol ≥2200 mg/l were less frequent in frequent egg consumption groups in both cohorts (trend P<0·0001). Subjects with <1 d/week of egg consumption were more likely to avoid a cholesterol-rich diet. Egg consumption was not associated with the risk of CHD, although total cholesterol was significantly related to the risk of CHD. The multivariate hazard ratio of CHD in subjects with total cholesterol ≥2400 v. <1800 mg/l was 2·17 (95 % CI 1·22, 3·85; trend P=0·0018). In conclusion, eating eggs more frequently, up to almost daily, was not associated with an increase in CHD incidence for middle-aged Japanese men and women. Subjects with hypercholesterolaemia were less frequently in frequent egg consumption groups, probably because they avoided eating eggs.