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Featured researches published by Yuya Tamai.


International Journal of Cancer | 2013

Soy isoflavone intake and breast cancer risk in Japan: from the Takayama study.

Keiko Wada; Kozue Nakamura; Yuya Tamai; Michiko Tsuji; Toshiaki Kawachi; Akihiro Hori; Naoharu Takeyama; Shinobu Tanabashi; Shogen Matsushita; Naoki Tokimitsu; Chisato Nagata

The effects of soy or isoflavone intake on breast cancer need to be examined further in epidemiologic studies. We assessed the associations of soy and isoflavone intake with breast cancer incidence in a population‐based prospective cohort study in Japan. Participants were members from the Takayama study, aged 35 years or older in 1992. The follow‐up was conducted from the time of the baseline study (September 1, 1992) to the end of March 2008. Cancer incidence was mainly confirmed through regional population‐based cancer registries. Breast cancer was defined as code C50 according to ICD‐10. Soy and isoflavone intakes were assessed with a validated food frequency questionnaire. Using the Cox proportional hazard models, the association of soy and isoflavone intake with breast cancer was assessed after adjustments for age, body mass index, physical activity, smoking, alcohol consumption, education, age at menarche, age at first delivery, menopausal status, number of children and history of hormone replacement therapy. Among the 15,607 women analyzed, 172 had developed breast cancer. The relative risks of postmenopausal breast cancer were lower among women with higher intakes of soy (trend p = 0.023) and isoflavone (trend p = 0.046), although the relative risks of premenopausal breast cancer were not associated with intakes of soy and isoflavone. Decreased risks of breast cancer were found even among women with a moderate intake of soy and isoflavone. These results suggested that soy and isoflavone intakes have a protective effect on postmenopausal breast cancer.


American Journal of Epidemiology | 2013

Branched-chain Amino Acid Intake and the Risk of Diabetes in a Japanese Community The Takayama Study

Chisato Nagata; Kozue Nakamura; Keiko Wada; Michiko Tsuji; Yuya Tamai; Toshiaki Kawachi

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.


Japanese Journal of Clinical Oncology | 2011

Cigarette smoking and other lifestyle factors in relation to the risk of pancreatic cancer death: a prospective cohort study in Japan.

Kozue Nakamura; Chisato Nagata; Keiko Wada; Yuya Tamai; Michiko Tsuji; Naoyoshi Takatsuka; Hiroyuki Shimizu

OBJECTIVE To examine the association of smoking and lifestyle factors with pancreatic cancer death in the prospective design. METHODS Mortality from pancreatic cancer in regard to smoking, body mass index, physical activity, and alcohol, coffee and green tea intake, was studied in a prospective cohort of 30,826 inhabitants in Takayama, Japan. In 1992, each subject completed a self-administered questionnaire on demographic information, smoking, drinking habits, diet, exercise and medical histories. The response rate was 85.3%. RESULTS From 1992 to 1999, 33 men and 19 women died due to pancreatic cancer. Hazard ratios and 95% confidence intervals were determined using Cox proportional hazards models. Women who were defined as current smokers at baseline had significant and increased risk of pancreatic cancer death after adjustment for age, body mass index and history of diabetes mellitus (Hazard ratio: 4.77, 95% confidence intervals: 1.58-14.4). There were significant positive associations of pancreatic cancer death with the years of smoking and the number of cigarettes consumed daily in women in a dose-dependent manner. Current smokers indicated a non-significant risk increase in men (Hazard ratio: 3.81, 95% confidence intervals: 0.88-16.6). Body mass index, physical activity, and alcohol, coffee and green tea intake were not significantly associated with pancreatic cancer death. CONCLUSIONS These data suggested that smoking increases the risk of death from pancreatic cancer in Japanese women.


Nutrition Journal | 2011

Seaweed intake and blood pressure levels in healthy pre-school Japanese children

Keiko Wada; Kozue Nakamura; Yuya Tamai; Michiko Tsuji; Yukari Sahashi; Kaori Watanabe; Sakiko Ohtsuchi; Keiko Yamamoto; Kyoko Ando; Chisato Nagata

BackgroundFew studies have examined whether dietary factors might affect blood pressure in children. We purposed to investigate whether seaweed intake is associated with blood pressure level among Japanese preschool children.MethodsThe design of the study was cross-sectional and it was conducted in autumn 2006. Subjects were healthy preschoolers aged 3-6 years in Aichi, Japan. Blood pressure and pulse were measured once by an automated sphygmomanometer, which uses oscillometric methods. Dietary data, including seaweed intake, were assessed using 3-day dietary records covering 2 consecutive weekdays and 1 weekend day. Of a total of 533 children, 459 (86.1 percent) agreed to be enrolled in our study. Finally, blood pressure measurement, complete dietary records and parent-reported height and weight were obtained for 223 boys and 194 girls.ResultsWhen we examined Spearmans correlation coefficients, seaweed intake was significantly negatively related to systolic blood pressure in girls (P = 0.008). In the one-way analysis of covariance for blood pressure and pulse after adjustments for age and BMI, the boys with the lowest, middle and highest tertiles of seaweed intake had diastolic blood pressure readings of 62.8, 59.3 and 59.6 mmHg, respectively (P = 0.11, trend P = 0.038). Girls with higher seaweed intake had significantly lower systolic blood pressure readings (102.4, 99.2 and 96.9 mmHg for girls with the lowest, middle and highest tertiles of seaweed intake, respectively; P = 0.037, trend P = 0.030).ConclusionOur study showed that seaweed intake was negatively related to diastolic blood pressure in boys and to systolic blood pressure in girls. This suggests that seaweed might have beneficial effects on blood pressure among children.


European Journal of Clinical Nutrition | 2012

Relationship of intake of plant-based foods with 6-n-propylthiouracil sensitivity and food neophobia in Japanese preschool children

Michiko Tsuji; Kozue Nakamura; Yuya Tamai; Keiko Wada; Yukari Sahashi; Kaori Watanabe; Sakiko Ohtsuchi; Kyoko Ando; Chisato Nagata

Background/Objectives:Diets rich in plant-based foods such as vegetables, fruits and soy foods have been suggested to have beneficial effects on health. However, phytochemicals contained in plant-based foods are generally bitter and acrid. We investigated whether intake of vegetables, fruits and soy foods is associated with sensitivity to bitterness and reluctance to eat new foods (food neophobia) in Japanese preschool children.Subjects/Methods:Subjects of this cross-sectional study were healthy Japanese, 167 boys and 156 girls, aged 4–6 years. Intake of vegetables, fruits and soy foods was estimated from 3-day dietary records. Subjects were classified as either tasters or non-tasters of 6-n-propylthiouracil (PROP) based on their ability to taste 0.56 mmol/l PROP. Information on each child’s age, height, weight, food neophobia status and food variety, as well as maternal diet and parental control over the child’s eating, was obtained by a parent-administered questionnaire. Food neophobia was assessed using the Child Food Neophobia Scale (CFNS).Results:A high intake of vegetables was significantly associated with a low CFNS score in boys after controlling for covariates (P=0.0008). Among the boys, soy food intake was significantly higher in PROP non-tasters than in tasters, except those with low CFNS scores (P=0.0019). High intake of soy foods was significantly associated with a low neophobia score in PROP tasters but not in non-tasters (P=0.0024).Conclusions:These data suggest that sensitivity to bitter taste and food neophobia may influence the consumption of vegetables and soy foods among Japanese preschool boys.


Cancer Science | 2013

Diabetes mellitus and risk of cancer in Takayama: A population-based prospective cohort study in Japan

Kozue Nakamura; Keiko Wada; Yuya Tamai; Michiko Tsuji; Toshiaki Kawachi; Akihiro Hori; Naoharu Takeyama; Shinobu Tanabashi; Shogen Matsushita; Naoki Tokimitsu; Chisato Nagata

Diabetes mellitus (DM) has been reported to be associated with an increased risk of site‐specific cancers; however, few studies have assessed associations of DM with both total and site‐specific cancers in Japan. We examined the association of a history of DM with cancer incidence in a population‐based prospective cohort study in Japan. A total of 14 173 men and 16 547 women over 35 years old, who completed a self‐administered baseline questionnaire in 1992, were followed up for cancer incidence from September 1992 to March 2008. At baseline, 6.3% men and 2.9% women had a history of diabetes. A total of 1974 men and 1514 women were identified as newly diagnosed with cancer. Hazard ratios (HR) and 95% confidence intervals (CI) were determined using Cox proportional hazards models. After controlling for potential confounders, men with DM had a modest risk increase of total cancer occurrence compared with those without DM (HR, 1.09; 95% CI, 0.93–1.29). Increased risk of cancer of the liver (HR, 2.18; 95% CI, 1.27–3.74), bile duct (HR, 2.17; 95% CI, 1.01–4.66), and larynx (HR, 3.61; 95% CI, 1.16–11.2) in diabetic men were observed. In women, significant increased risk of total cancer (HR, 1.35; 95% CI, 1.06–1.73) and stomach cancer (HR, 2.15; 95% CI, 1.30–3.54) were observed among diabetic subjects. These data suggest that people with DM may be at increased risk of both total and some site‐specific cancers.


Public Health Nutrition | 2013

Associations of intake of antioxidant vitamins and fatty acids with asthma in pre-school children

Kozue Nakamura; Keiko Wada; Yukari Sahashi; Yuya Tamai; Michiko Tsuji; Kaori Watanabe; Sakiko Ohtsuchi; Kyoko Ando; Chisato Nagata

OBJECTIVE Increasing childhood asthma rates may be due to changing dietary lifestyle. We investigated the association of dietary intake of antioxidant vitamins and fatty acids with asthma in Japanese pre-school children. DESIGN Cross-sectional study. SETTING School-based survey on lifestyle/diet and health status in children in Japan. SUBJECTS Parents of 452 children aged 3-6 years completed a questionnaire on the childrens and parents’ lifestyle and demographics. Children were classified into asthma cases and non-asthma cases in accordance with the ATS-DLD(American Thoracic Society and Division of Lung Diseases of the National Heart, Lung, and Blood Institute) questionnaire. Childrens diet was assessed using a 3 d dietary record completed by parents. Childrens age, sex, BMI, history of food allergy, maternal age, parental history of allergy, maternal education,family size and second-hand smoking were included as covariates. Logistic regression models were used to examine the association between childrens diet and asthma. RESULTS Compared with children with the lowest intake tertile for vitamin C and vitamin E, those in the highest were significantly inversely associated with asthma; adjusted OR (95% CI) were 0?35 (0?14, 0?88) and 0?32 (0?12, 0?85),respectively. A statistically significant trend was also observed. Fruit intake showed an inverse but insignificant association with asthma. There were no associations of any type of fatty acids with asthma. CONCLUSIONS These data suggest that children with high intakes of vitamins C and E may be associated with a reduced prevalence of asthma.


Menopause | 2012

Associations of physical activity and diet with the onset of menopause in Japanese women.

Chisato Nagata; Keiko Wada; Kozue Nakamura; Yuya Tamai; Michiko Tsuji; Hiroyuki Shimizu

ObjectiveProspective studies on physical activity and diet and the onset of natural menopause are scarce. The aim of this study was to examine the association of physical activity and dietary factors potentially related to endogenous estrogen levels such as fats, dietary fiber, soy isoflavones, and alcohol with the onset of menopause in a cohort of premenopausal women. MethodsStudy participants were 3,115 premenopausal Japanese women aged 35 to 56 years derived from the participants in the Takayama Study. Physical activity was assessed by a validated questionnaire at baseline, and the metabolic equivalent score was calculated. The dietary intakes were estimated by a validated food frequency questionnaire at baseline and adjusted for total energy. Menopause status was defined as the absence of menstruation for 12 months or more. The Cox proportional hazard model was used to estimate the hazard ratio of the occurrence of menopause after controlling for age, parity, body mass index, smoking status, years of education, and lifelong irregular menstrual cycle. ResultsDuring the 10-year follow-up, 1,790 women experienced natural menopause. A high physical activity level and a high intake of polyunsaturated fat were moderately but significantly associated with the earlier onset of menopause; the hazard ratios for the highest versus lowest quartile were 1.17 (95% CI, 1.02-1.34) for physical activity and 1.15 (95% CI, 1.01-1.31) for polyunsaturated fat intake. Total fat, other types of fat, dietary fiber, soy isoflavones, and alcohol were not associated with the onset of menopause. ConclusionsThese data suggest that high levels of physical activity and polyunsaturated fat intake are associated with earlier onset of menopause.


Annals of Otology, Rhinology, and Laryngology | 2013

Association between tinnitus and sleep disorders in the general Japanese population.

Keiichi Izuhara; Keiko Wada; Kozue Nakamura; Yuya Tamai; Michiko Tsuji; Yatsuji Ito; Chisato Nagata

Objectives: There are few studies about the association between tinnitus and sleep disorders in the general population worldwide. This study assessed this association in a Japanese community. Methods: A total of 14,027 participants 45 to 79 years of age who were in the Takayama Study responded to a self-administered questionnaire about tinnitus and sleep disorders. Results: Of this population, 13.3% of men and 10.6% of women had current tinnitus. The percentages of insomnia, respectively, among individuals with and without tinnitus were 28.1% in men and 36.1% in women and 18.8% in men and 21.5% in women. There were 1.7-fold (95% confidence interval [CI], 1.4 to 2.1) and 1.8-fold (95% CI, 1.5 to 2.2) increases in the odds ratios (ORs) of insomnia for those with tinnitus compared with those without tinnitus in men and women, respectively. Loud or very loud tinnitus was associated with 2.8-fold (95% CI, 1.8 to 4.3) and 3.3-fold (95% CI, 1.9 to 5.6) increases in the OR of insomnia in men and women, respectively. Even low (ie, quiet) or moderate tinnitus was significantly associated with insomnia. Difficulty initiating sleep, difficulty maintaining sleep, and a poor perceived quality of sleep were also significantly associated with tinnitus. Conclusions: Insomnia and other sleep disorders were significantly associated with tinnitus in Japanese adults.


American Journal of Hypertension | 2011

Dietary Intake of Vitamin B12 and Folic Acid Is Associated With Lower Blood Pressure in Japanese Preschool Children

Yuya Tamai; Keiko Wada; Michiko Tsuji; Kozue Nakamura; Yukari Sahashi; Kaori Watanabe; Keiko Yamamoto; Kyoko Ando; Chisato Nagata

BACKGROUND An elevated plasma homocysteine level is an independent risk factor for high blood pressure and cardiovascular disease, and its level is regulated by three vitamins; vitamin B6, B12, and folic acid. Until now, the association between the intake of these vitamins and blood pressure has been examined only in adult populations. We purposed to examine the association between dietary intake of these three vitamins and blood pressure of young children. METHODS We conducted a cross-sectional study at Japanese preschools in 2006. Blood pressure was measured among 418 children aged 3-6 years. Diets including vitamins were assessed by a 3-day dietary record. We compared the blood pressure levels among the four groups defined according to quartile of energy-adjusted vitamin intake by using analysis of covariance after controlling for age, sex, and body mass index. RESULTS The mean systolic blood pressure was 6.6 mm Hg lower and the mean diastolic blood pressure was 5.7 mm Hg lower in the highest quartile than in the lowest quartile of vitamin B12 intake (P for trend was <0.001 and 0.006, respectively). The mean systolic blood pressure was 4.1 mm Hg lower in the highest quartile than in the lowest quartile of folic acid intake (P for trend = 0.004). Vitamin B6 intake was not significantly associated with blood pressure. CONCLUSIONS The data suggest that high intakes of folic acid and vitamin B12 are associated with lower levels of blood pressure among preschool children.

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