The Hekinan Children's Study: Design and Profile of Participants at Baseline.

BACKGROUND: The early life environment is now recognized as a key factor contributing to susceptibility to certain diseases in later life. METHODS: We initiated a cohort study among school children in 2011 to primarily investigate the associations between lifestyle and environmental factors and some surrogate markers of chronic diseases, such as cardiometabolic risk factors (ie, obesity, high blood pressure, high blood glucose, insulin, or lipids) and cancer risk factors (ie, height and age at menarche). A baseline questionnaire asked for information, including demographic variables, medical history and use of medication, dietary habits, physical activity, sleep habits, and behavioral and emotional problems of children. Follow-up surveys are planned for the fourth grade of elementary school and the first grade of junior high school. At these follow-up surveys, fasting blood samples will be obtained to measure cardiometabolic markers. We also checked the validity of a food frequency questionnaire, which was originally created for 6-year-olds but was modified for use in older children. RESULTS: A total of 3,141 first-year students at elementary schools in Hekinan City, Aichi Prefecture, participated in the study. The response rate was 87.4%. The means of age and body mass index were 6.99 (standard deviation, 0.28) years and 15.3 (standard deviation, 1.7) kg/m2, respectively, in the 3,067 Japanese children (1,639 boys and 1,428 girls). CONCLUSIONS: This cohort will reveal determinants of cardiometabolic risk factors and cancer risk factors during childhood.

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 children's 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. Children's diet was assessed using a 3 d dietary record completed by parents. Children's 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 children's 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.

Dietary intake of vitamin B12 and folic acid is associated with lower blood pressure in Japanese preschool children.

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.

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

BACKGROUND: Few 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. METHODS: The 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. RESULTS: When we examined Spearman's 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). CONCLUSION: Our 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.

Soy intake and urinary sex hormone levels in preschool Japanese children.

The authors investigated whether soy intake is associated with sex steroid levels in Japanese children. This cross-sectional study was conducted in autumn 2006. Subjects were substantially healthy preschoolers, 230 boys and 198 girls, aged 3-6 years. Dietary data, including soy intake, were assessed using 3-day dietary records. Each child's dietary intake was controlled for total energy intake using the Willett method (Nutritional Epidemiology. Oxford, United Kingdom: Oxford University Press; 1990:245-271). Urinary estrone, estradiol, testosterone, and 5-androstene-3ß,17α diol levels measured using liquid chromatography-electrospray ionization tandem mass spectrometry, and urinary dehydroepiandrosterone level measured with a radioimmunoassay, were adjusted for urinary creatinine levels. In the analysis of covariance for sex steroids after adjustments for age and body mass index, soy intake was significantly negatively related to estrone and estradiol in boys and positively related to testosterone and 5-androstene-3ß,17α diol in girls. Isoflavone had a significant tendency to be negatively associated with estradiol in boys and to be positively associated with testosterone in girls. Total energy intake was not associated with any sex steroids in boys or girls. These results suggest that soy intake might affect the secretion or metabolism of sex steroids in childhood and that the effects might differ by sex.

Validity and reproducibility of food frequency questionnaire in Japanese children aged 6 years.

The aim of the present study was to evaluate the validity and reproducibility of a food frequency questionnaire (FFQ) for use among young Japanese children. Forty-seven mothers of children aged 6 y completed two 3-d diet records and two FFQs over a 6-mo period. The FFQ asked the mothers how often, on average, their children consumed each of the 162 food items listed and what the usual serving size of each item was during the 6 mo prior to the study. Intakes of macro- and micronutrients were estimated by multiplying the frequency by the serving size for each food item. The validity of the FFQ was assessed by comparison of the two 3-d diet records. The reproducibility of the FFQ was based on the first and second FFQ administrations. The validity correlation ranged from 0.05 for α-tocopherol to 0.59 for retinol. The median correlation was 0.40. The reproducibility correlation was higher than 0.50 for all nutrients. For most nutrients, FFQ had acceptable reproducibility, whereas validity showed low to moderate correlations. Our FFQ could reasonably rank individuals according to dietary intake for epidemiologic studies, although the validity of the questionnaire is limited to specific nutrients.

Consumption of vegetables alters morning urinary 6-sulfatoxymelatonin concentration.

Melatonin, which is contained in certain vegetables, may have an influence on circulatory melatonin concentrations. This study examined the effects of the consumption of vegetables on 6-sulfatoxymelatonin concentrations in morning urine. Ninety-four healthy women aged 24-55 were recruited through a city public health center in Japan. The women randomly allocated to the intervention group were requested to consume high amounts of six selected vegetables, with a target of 350 g/day for 65 days, while those in the control group were asked to avoid the same six vegetables during the same period. First-void morning urine was collected before and at the end of the intervention period, and creatinine-adjusted 6-sulfatoxymelatonin concentrations were measured. At the end of the intervention period, daily mean intake of melatonin from the six vegetables was 1288.0 ng in the intervention group and 5.3 ng in the control group. In the intervention group, the mean concentration of 6-sulfatoxymelatonin changed from 48.1 [95% confidence interval (CI): 40.4-57.2] ng/mg creatinine to 49.6 (95% CI: 42.8-57.3) ng/mg creatinine across the intervention period. In the control group, the mean concentration of 6-sulfatoxymelatonin changed from 55.5 (95% CI: 48.7-63.2) ng/mg creatinine to 50.8 (95% CI: 44.0-58.7) ng/mg creatinine across the intervention period. A comparison of the two groups with regard to the changes in the 6-sulfatoxymelatonin concentrations across the intervention period showed a significant difference (P = 0.03). The results indicate that increased consumption of vegetables raises circulatory melatonin concentrations.

Association of maternal fat and alcohol intake with maternal and umbilical hormone levels and birth weight.

High levels of estrogen during pregnancy have been hypothesized to increase the risk of breast cancer in offspring. Some studies have reported a positive association of estrogen level during pregnancy with fetal size, which has been linked to the subsequent risk of breast cancer in offspring. We examined whether maternal diet, including fat and alcohol intake, was associated with hormone levels during pregnancy, as well as with birth weight. The concentrations of estradiol, estriol, and testosterone were measured in the maternal serum and umbilical cord blood of 189 women during pregnancy and at delivery. Intakes of fat, alcohol, and other nutrients were assessed by 5-day diet records at approximately the 29th week of pregnancy before blood sampling. Intake of polyunsaturated fatty acids was moderately but significantly positively correlated with the umbilical cord estriol level (r = 0.17, P = 0.03) after controlling for covariates. The positive association between intake of polyunsaturated fatty acids and birth weight was of borderline significance (r = 0.14, P = 0.06). Intake of long-chain n-3 fatty acids was significantly inversely correlated with the umbilical cord estradiol and testosterone levels (r = -0.18, P = 0.02 and r = -0.24, P = 0.002, respectively). Alcohol intake was significantly positively correlated with the maternal estradiol level in the 29th week of pregnancy (r = 0.19, P = 0.01), but was unrelated to birth weight. Estrogen level during pregnancy may be regulated by dietary polyunsaturated fatty acids and mediate their effects on fetal growth.

Associations among maternal soy intake, isoflavone levels in urine and blood samples, and maternal and umbilical hormone concentrations (Japan).

OBJECTIVES: In utero exposure to high levels of endogenous estrogens has been hypothesized to increase breast cancer risk in later life. A high intake of soy has been suggested to protect against breast cancer. We examined the hypothesis that maternal soy intake may be inversely associated with pregnancy hormone levels. METHODS: The concentrations of hormones (estradiol, estriol, and testosterone) and isoflavones (genistein, deidzein, and equol) were measured in the maternal urine and serum, and umbilical cord blood of 194 women during pregnancy and at delivery. Soy intake during pregnancy was assessed by 5-day diet records at approximately the 29th week of pregnancy. RESULTS: High correlations were observed for isoflavone levels between maternal samples and umbilical cord blood, indicating that isoflavone can be transferred from the maternal to the fetal compartment. None of the hormones measured in umbilical cord blood was significantly associated with any of the isoflavones measured. There were a few significant associations between maternal hormone levels and isoflavone measures during pregnancy, but their patterns of associations varied by gestational week and differed depending on whether isoflavone exposure was measured by diet records, urine or serum. CONCLUSION: Our data contain no strong evidence showing that soy intake affects hormone levels during pregnancy.