Michiko Tsuji

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

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.

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

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.

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

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.

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

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.

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

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.

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

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.

Soy isoflavone intake and stomach cancer risk in Japan: From the Takayama study: Isoflavone and Stomach Cancer Risk in Japan

Although several experimental studies suggested that soy isoflavone intake inhibits the growth of stomach cancer, previous epidemiological studies have observed inconsistent results. We evaluated the associations of soy or isoflavone intake with stomach cancer incidence after considering several lifestyle factors, including salt intake, in a population‐based prospective cohort study in Japan. Subjects were 14,219 men and 16,573 women aged 35 years or older in September 1992. Soy and isoflavone intakes, assessed with a validated food‐frequency questionnaire, were controlled for the total energy intake. Cancer incidence was mainly confirmed through regional population‐based cancer registries. Until March 2008, 441 men and 237 women developed stomach cancer. After adjustments for multiple confounders, a significantly decreased relative risk of stomach cancer was observed in the highest vs. lowest quartile of soy intake; the estimated hazard ratios were 0.71 (95% CI: 0.53, 0.96) for men (p for trend = 0.039) and 0.58 (95% CI: 0.36, 0.94) for women (p for trend = 0.003). Similar inverse associations between isoflavone intake and stomach cancer risk were also observed in women. Higher intake of non‐fermented soy foods was significantly associated with a lower risk of stomach cancer (p for trend: 0.022 in men and 0.005 in women), whereas there was no significant association between the intake of fermented soy foods and a risk of stomach cancer. These results suggest that a high intake of soy isoflavone, mainly nonfermented soy foods, have a protective effect against stomach cancer.

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

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.

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

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.

Dietary soy and natto intake and cardiovascular disease mortality in Japanese adults: the Takayama study

BACKGROUND Whether soy intake is associated with a decreased risk of cardiovascular disease (CVD) remains unclear. A traditional Japanese soy food, natto, contains a potent fibrinolytic enzyme. However, its relation to CVD has not been studied. OBJECTIVE We aimed to examine the association of CVD mortality with the intake of natto, soy protein, and soy isoflavones in a population-based cohort study in Japan. DESIGN The study included 13,355 male and 15,724 female Takayama Study participants aged ≥35 y. At recruitment in 1992, each subject was administered a validated semiquantitative food-frequency questionnaire. Deaths from CVD were ascertained over 16 y. RESULTS A total of 1678 deaths from CVD including 677 stroke and 308 ischemic heart disease occurred during follow-up. The highest quartile of natto intake compared with the lowest intake was significantly associated with a decreased risk of mortality from total CVD after control for covariates: the HR was 0.75 (95% CI: 0.64, 0.88, P-trend = 0.0004). There were no significant associations between the risk of mortality from total CVD and intakes of total soy protein, total soy isoflavone, and soy protein or soy isoflavone from soy foods other than natto. The highest quartiles of total soy protein and natto intakes were significantly associated with a decreased risk of mortality from total stroke (HR = 0.75, 95% CI: 0.57, 0.99, P-trend = 0.03 and HR = 0.68, 95% CI: 0.52, 0.88, P-trend = 0.0004, respectively). The highest quartile of natto intake was also significantly associated with a decreased risk of mortality from ischemic stroke (HR = 0.67, 95% CI:0.47, 0.95, P-trend = 0.03). CONCLUSION Data suggest that natto intake may contribute to the reduction of CVD mortality.