Dietary Amino Acid Composition and Glycemic Biomarkers in Japanese Adolescents.

Protein intake reportedly increases the risk of diabetes; however, the results have been inconsistent. Diabetes in adulthood may be attributed to early life dietary amino acid composition. This study aimed to investigate the association between amino acid composition and glycemic biomarkers in adolescents. Dietary intake was assessed using a food frequency questionnaire, and fasting glucose and insulin levels were measured in 1238 eighth graders. The homeostatic model assessment (HOMA) indices (insulin resistance and ß-cell function) were calculated. Anthropometrics were measured and other covariates were obtained from a questionnaire. Amino acid composition was isometric log transformed according to the compositional data analysis, which was used as explanatory variables in multivariate linear regression models for glucose, insulin, and HOMA indices. Only the association between glucose and leucine was significant. In replacement of other amino acids with leucine, an increase of 0.1% of total amino acids correlated with a lower glucose level (-1.02 mg/dL). One-to-one substitution of leucine for isoleucine or methionine decreased glucose (-2.98 and -2.28 mg/dL, respectively). Associations with other biomarkers were not observed. In conclusion, compositional data analysis of amino acids revealed an association only with glucose in adolescents; however, the results of this study should be verified in other populations.

Assessment of Foods Associated with Sodium and Potassium Intake in Japanese Youths Using the Brief-Type Self-Administered Diet History Questionnaire.

The identification of sodium and potassium intake in youths is an important step to preventing the increase of blood pressure in childhood. We examined food intake and estimated mineral intake using a brief-type self-administered diet history questionnaire (BDHQ) to test its validity as a comparison with urinary excretion in Japanese youths. The subjects were 5th and 8th graders (n = 2377), who completed the BDHQ and permitted the use of their overnight urine specimens. Sodium intake was poorly associated with sodium excretion (Rho = 0.048), and the coefficients of dietary potassium and a sodium-to-potassium molar ratio were 0.091-0.130. Higher soybean paste (miso) intake and pickles were significantly associated with higher sodium excretion (p ≤ 0.005). However, these foods were positively associated with potassium excretion (p = 0.002-0.012), and not associated with an excreted sodium-to-potassium ratio. Fruits and dairy products were positively associated (p ≤ 0.048), whereas beverages were negatively associated with potassium excretion (p ≤ 0.004). The association of the sodium-to-potassium ratio was opposite to that of potassium (p ≤ 0.001). The choice of foods, potassium, and the sodium-to-potassium ratio assessed using the BDHQ are available as part of health education for youths, but the assessment of sodium intake in population levels should be carefully conducted.

Composition of Dietary Fatty Acids and Health Risks in Japanese Youths.

In the overall composition of dietary fatty acids (FAs), the quantity of each FA is interrelated with that of others. We examined the associations between dietary FA composition and cardiometabolic risk in Japanese youths. Risk factors (anthropometric characteristics, serum lipid and liver enzyme levels, and blood pressure) were measured in 5485 junior-high-school students. Dietary intake was assessed using a food frequency questionnaire. The mean saturated FA (SFA), monounsaturated FA (MUFA), omega-6 polyunsaturated FAs (PUFAs), and omega-3 PUFAs intake were 9.6%E, 10.3%E, 6.3%E, and 1.1%E, respectively. In compositional regression analysis controlled for confounders, a high intake of omega-6 PUFAs relative to others was associated with low low-density-lipoprotein cholesterol levels (LDL-C; p = 0.003), and relative SFA intake was associated with high levels of gamma-glutamyl transpeptidase (p = 0.019). Relative omega-3 PUFAs intake was associated with low blood pressure (p = 0.005-0.034) but had unfavorable effects on adiposity and alanine transaminase. Substitutional models showed similar results for omega-6 PUFAs on LDL-C, but MUFA had inconsistent effects on risk factors. The results from the compositional data analysis were consistent with previous studies and clinical practice/knowledge. Focusing on increasing omega-6 PUFAs in Japanese youths could have favorable consequences in the long term.

Adherence to the Japanese Food Guide: The Association between Three Scoring Systems and Cardiometabolic Risks in Japanese Adolescents.

The Japanese Food Guide Spinning Top (JFGST) indicates optimal intake of five food groups (grain, fish and meat, vegetables, milk, and fruits) and sugar and confectionaries. We aimed to investigate whether adherence to the JFGST in 8th grade junior high school students (n = 3162) was associated with cardiometabolic risks and how different scorings of the JFGST influenced the associations. Metabolic risks were assessed from anthropometrics, blood pressure measurements, and blood glucose and lipid profile measurements. Three types of scoring adherent to the JFGST were analyzed (10 points were given for each item with optimal intake; range: 0-60): the original scoring (ORG scoring); first modified scoring, which had no upper limits for vegetables and fruits (MOD1 scoring); and MOD2 scoring without upper limits for five dishes (MOD2 scoring). The MOD2 scoring was positively associated with dietary fiber, potassium, calcium, and vitamins. All types of scorings were associated with low glucose levels (p ≤ 0.001); the MOD2 scoring was associated with low systolic blood pressure (p = 0.001) and low cardiometabolic risk (p = 0.003). Our findings suggest that Japanese adolescents adherent to the JFGST had low cardiometabolic risks and should not fall below lower limits for intake of the abovementioned five food groups.

Estimation of daily sodium and potassium excretion from overnight urine of Japanese children and adolescents.

BACKGROUND: Estimates of daily sodium (Na) and potassium (K) excretion were explicitly biased when using equations for adults. We aimed to develop equations to estimate them using overnight urine from Japanese children and adolescents. METHODS: The subjects comprised 70 students aged 10.49-15.76 years: validation group, n = 34; and verification group, n = 36. Each subject performed two operations of overnight spot urine (Um) and 24-h urine (U24) sampling. Concentrations of Na, K, and creatinine (Cr) were measured, and anthropometrics were recorded. In the validation group, Na/Cr, and K/Cr (mEq L-1/mg dL-1) in 24-h urine were predicted from their correspondents in overnight urine. Daily Cr excretion (EstCr24; mg d-1) was estimated according to Mage's method. RESULTS: In validation, we formulated Na excretion (mg d-1) = 23 × exp (0.2085) × [(Na/CrUm + 1)1.0148 - 1] × 1.078 × EstCr24/10; and K excretion (mg d-1) = 39 × exp (0.0315) × [(K/CrUm + 1)1.3165 - 1] × 1.078 × EstCr24/10. For verification, we compared estimates with the measured 24-h Na excretion 3596 ± 1058 mg d-1, and K excretion 1743 ± 569 mg d-1. The mean biases and intraclass correlations (3, 1) were -131 mg d-1 and 0.60, respectively for Na excretion; and -152 mg d-1 and 0.55 for K excretion. CONCLUSION: We obtained validated equations to estimate daily Na and K excretion with accessible variables such as Na, K, and Cr concentrations of overnight urine, body height and weight, and age for children and adolescents. When using the obtained equations, caution should be paid to small but definite biases and measurement errors.

Added and Free Sugars Intake and Metabolic Biomarkers in Japanese Adolescents.

Reduction in the intakes of added and free sugars is a recommendation to lower cardiometabolic risks. Sugars intake is considered lowest in the Asian-Pacific region, particularly Japan. We examined the association between sugars intake and cardiometabolic risks in Japanese adolescents. We included 3242 students (mean age, 13.56 years) living in Shunan City, Japan, between 2006 and 2010. Sugars intake was estimated using the brief-type self-administered diet history questionnaire. Anthropometrics, serum lipids, fasting plasma glucose, and blood pressure were measured. Metabolic syndrome was determined by the combination of overweight and other risks. Intakes of added and free sugars were 7.6-7.9%E and 8.4-8.8%E of the total energy intake (%E), respectively. Categories based on quintiles of added or free sugars intakes were associated with fasting glucose, systolic blood pressure, and the z-score of metabolic syndrome (Ptrend ≤ 0.025). Other than the association between added sugars ≥10%E and high glucose (odds ratio 1.51, 95% confidence interval 1.04-2.19, p = 0.031), non-significantly high intakes of added or free sugars for risks occurred. Association was observed between added or free sugars intake and cardiometabolic biomarkers in Japanese adolescents, and added sugars intake <10%E could prevent glucose intolerance but not metabolic syndrome.

Proportion of Japanese primary school children meeting recommendations for 24-h movement guidelines and associations with weight status.

BACKGROUND: 24-h movement guidelines were recently developed to improve both the present and future health of children. The purpose of the present study was to evaluate adherence to the three recommendations strongly associated with health in 24-h movement guidelines and their relationship with weight status (overweight/obesity or underweight) in Japanese primary school children. METHODS: This cross-sectional study was based on 902 children. Weight status according to measured body mass index (BMI) was classified by the WHO growth reference. Meeting the 24-h movement guidelines was defined as: 9-11 h/night of sleep, ≤2 h/day of screen time, and at least 60 min/day of moderate-to-vigorous physical activity (MVPA). RESULTS: The prevalence of children meeting the all three recommendations was 10.5% and 13.2% met none of the three recommendations. Children meeting all three behaviors recommendation, screen time and MVPA or sleep recommendations, or only screen time recommendation had lower odds ratios adjusted for age, gender and socioeconomic status of each school for overweight/obesity compared to children meeting none of the 3 recommendations. CONCLUSIONS: The screen time recommendation or combinations including screen time recommendation were associated with overweight/obesity. On the other hand, none of the recommendations was associated with underweight.

Association between 24-hour movement guidelines and physical fitness in children.

BACKGROUND: Physical fitness levels in Japanese children are lower than those in the 1980s. Twenty-four hour movement guidelines were recently developed to improve both present and future health of children. This study examined whether meeting the 24 h movement guidelines was associated with physical fitness measures in primary school children. METHODS: Participants were 243 Japanese children (9.4 ± 1.7 years). Moderate-to-vigorous physical activity (MVPA) was evaluated using accelerometry. Sleep duration and screen time were reported. Physical fitness was assessed by grip strength, sit-ups, sitting trunk flexion, and 20 m shuttle run test. Meeting the 24 h movement guidelines was defined as: 9-11 h / night of sleep, ≤2 h/day of screen time, and at least 60 min/day of MVPA. The associations between physical fitness and the recommendations were analyzed using analysis of covariance. RESULTS: Children meeting the MVPA recommendation alone performed better on the 20 m shuttle run and sit-up test compared to those not meeting the recommendation (number of laps: 41 vs 36, P = 0.009 and number of repetitions: 16.3 vs 14.7, P = 0.021). Children meeting the combination of MVPA and sleep recommendation scored significantly higher on the sit-up test compared to those not meeting the recommendations (number of repetitions: 16.5 vs 15.0, P = 0.038) but the effect was similar to that of the MVPA reference only. Meeting all three 24 h movement guidelines was not associated with measures of fitness in this sample. Meeting the MVPA recommendation was associated with greater aerobic fitness and muscle endurance. CONCLUSIONS: In order to enhance children's physical fitness, public health recommendations should primarily target MVPA.

Gender differences in physical activity and sedentary behavior of Japanese primary school children during school cleaning time, morning recess and lunch recess.

BACKGROUND: The school environment provides crucial opportunities for children to engage in health-promoting physical activity (PA). Japanese children clean their schools and have recess time every school day. The primary aim of the study is to describe the levels of physical activity during school cleaning and recess time while comparing it between genders. METHODS: PA and sedentary behavior (SB) of 230 boys and 252 girls aged 6-12 years-old from 14 public primary schools were assessed for 7 consecutive days with a triaxial accelerometer. Minutes of SB, and moderate-to-vigorous PA (MVPA) as a percentage in each of school cleaning time (15 min/day: 58% of the 14 schools or 20 min/day), morning recess time (15 min/day: 6% or 20 min/day) or lunch recess time (15 min/day: 29%, 20 min/day: 47% or 25 min/day) were evaluated. A one-way analysis of variance or Student's t test was used to examine differences in %PAs and %SB between school cleaning time and morning and lunch recess time, and between genders. RESULTS: In a school day, the percentage of total daily MVPA during school cleaning time, morning recess and lunch recess time was 19.4 ± 6.8% (15.2 ± 5.3 min/day) for boys and 16.9 ± 5.8% (10.5 ± 4.3 min/day) for girls. For boys, the proportions of MVPA in morning and lunch recesses and SB during the morning recess were significantly higher than during school cleaning time (p < 0.001). For girls, similar results were obtained and the SB during lunch recess was also higher than during school cleaning time (p < 0.001). CONCLUSIONS: These findings suggest that the total amount of school cleaning time, recess and lunch time likely contribute to daily MVPA but the beneficial effects should be further explored in future intervention studies.

The Relationship between Functional Constipation and Dietary Habits in School-Age Japanese Children.

Functional constipation negatively affects school-related quality of life for children and adolescents. We investigated the association between functional constipation, defined according to the Rome criteria version III, and dietary habits. The subjects of this cross-sectional study were 1,140 5th graders and 1,054 8th graders attending schools in Shunan City, Japan in 2012. Functional constipation was defined as having two or more symptoms of constipation. Dietary habits were assessed using a brief questionnaire. Self-reported biological, demographic and lifestyle information was obtained. Using multiple logistic models, dose-dependent associations among subgroups stratified with quintiles of nutrient and food intake were examined. The prevalence of functional constipation ranged from 3.7% to 8.3% across the grades. The most prevalent symptom was pain or hard stools. There was a link between higher rates of functional constipation and lower levels of dietary fiber intake, vegetables, and fruits (ptrend=0.010-0.030). Associations with vegetables and fruits attenuated when controlling for dietary fiber intake (ptrend=0.074-0.150). When 5th and 8th graders were separately analyzed, intake of dietary fiber, water from foods, and vegetables had beneficial effects on functional constipation in 8th graders (ptrend=0.005-0.038), and fruit intake had a beneficial effect in 5th graders (ptrend=0.012). Modification of dietary habits may have a positive effect in reducing functional constipation in school-age children. Diets rich in fiber, vegetables, and fruits, have the potential to improve functional constipation in Japanese children and adolescents.

Protein Intake Estimated from Brief-Type Self-Administered Diet History Questionnaire and Urinary Urea Nitrogen Level in Adolescents.

Our aim was to assess the validity of the brief-type self-administered diet history questionnaire (BDHQ15y) to estimate the protein intake in 248 Japanese secondary school students (mean age = 14.2 years), using urinary biomarkers as references. Participants provided three samples of overnight urine for measurement of urea nitrogen and creatinine levels, underwent anthropometric measurements, and answered the questionnaires. Additionally, 58 students provided 24-h urine specimens. A significant correlation was observed between excretion of urea nitrogen in overnight and 24-h urine specimens (ρ = 0.527; p < 0.001), with biases ≤5.8%. The mean daily protein intake estimated from urinary biomarkers was 76.4 ± 20.4 g/d in males and 65.4 ± 16.9 g/d in females, and the mean protein intake estimated from the BDHQ15y (PRTbdhq) was 89.3 ± 33.7 g/d in males and 79.6 ± 24.6 g/d in females. Crude and energy-adjusted coefficients of correlation between PRTbdhq and protein intake estimated from urinary biomarkers were 0.205 (p = 0.001; 0.247 for males and 0.124 for females), and 0.204 (p = 0.001; 0.302 for males and 0.109 for females), respectively. The BDHQ15y is a low-cost tool to assess protein intake of a large population, instead of a weakness of overestimation.

Association between age at onset of independent walking and objectively measured sedentary behavior is mediated by moderate-to-vigorous physical activity in primary school children.

OBJECTIVE: Age at onset of walking has been shown as an early predictor of physical activity in infants and children. However, little is known about whether age at onset of walking may predict sedentary behavior (SB). The aim of the present study was to examine the association between the timing of onset of walking and objectively measured SB, and whether this association is mediated by moderate-to-vigorous physical activity (MVPA) in children. METHODS: The subjects were 388 elementary school children aged 6-12 years. Current weight and height data were collected. Birth weight and the age in months the child first walked independently were reported based on the parents' recall. Children's SB and physical activity were objectively measured using a triaxial accelerometer (Active style Pro HJA-350IT, OMRON). The following summary outcome variables were derived from accelerometer data: Time (min/day) spent in SB (≤1.5 metabolic equivalents [METs]) and MVPA (≥3.0 METs). RESULTS: The mean ± SD time (min/day) spent in sedentary was 376 ± 62 and MVPA was 67.6 ± 20.8. Multiple linear regression analyses revealed that a later age at independent walking was associated with increased time spent in SB (ß = 0.15, P < 0.001) and decreased time spent in MVPA (ß = -0. 18, P < 0.001) after adjusting for gender, birth weight, current age, body weight, schools, and time spent wearing the accelerometer. When MVPA was introduced as a covariate in the model predicting SB, the association between the age at independent walking and time spent in SB was completely attenuated (ß = 0.04, P = 0.215), while MVPA was significantly associated with SB (ß = -0.61, P < 0.001). CONCLUSIONS: Our results indicate that infants who walked at a later age spent more time in SB in childhood, and this association is mediated by MVPA. Appropriate interventions which focus on increasing MVPA and thereby reducing SB may be beneficial in infants who demonstrate a later age at onset of independent walking.

Associations of Physical Activity and Sedentary Time in Primary School Children with Their Parental Behaviors and Supports.

BACKGROUND: The associations of objectively evaluated moderate-to-vigorous physical activity (MVPA) and sedentary time between primary school children and their fathers or mothers have not been fully understood. Therefore, we tested the associations in children. Methods: The participants were first to sixth grade boys (n = 166, 9.4 ± 1.6 years) and girls (n = 202, 9.4 ± 1.6 years) and their parents (fathers, n = 123 and mothers, n = 321). MVPA and sedentary time were measured using triaxial accelerometry. The relationship between parental support which was assessed by self-reported questionnaire and children's MVPA was also examined. RESULTS: MVPA in the children was positively correlated with maternal MVPA after adjustment for the children's gender, grade, body mass index z-score, paternal or maternal age, and school (p < 0.001). However, paternal or maternal sedentary time and paternal MVPA showed no significant association with sedentary time or MVPA in children. On the other hand, the percentage of MVPA in children who spent more time with their mothers on weekends was significantly lower than those who spent less time (p = 0.034). Children whose mothers watched their sports events had a significantly higher percentage of MVPA than those whose mothers did not watch these events (p = 0.008). There were no associations between children's MVPA and paternal support. CONCLUSIONS: The findings of this study demonstrate the significance of maternal MVPA and support.

Variability in school children's activity occurs in the recess and before-school periods.

BACKGROUND: An accurate description of physical activity (PA) at school is required for appropriate health interventions. We examined PA patterns in children, and identified the time periods that influenced them. METHODS: Forty students in five Japanese primary schools were asked to wear triaxial accelerometers for ≥7 days. We obtained coefficients of variance (CV) at 15 min intervals, and conducted factor analysis of the school periods. A questionnaire was used to investigate where students spent time before school, and during recess. RESULTS: The amount of PA, and its CV were higher around 8 a.m. (before-school period), 10 a.m. (morning recess), 1 p.m. (lunch recess), and 4 p.m. (commuting home from school). Moderate-vigorous PA (MVPA; ≥3.0 metabolic equivalent units [MET]) was highest during lunch recess and the after-school period (12.9 ± 7.4 min and 12.6 ± 6.2 min, respectively). The percentage of MVPA time was high (>15%) in the before-school period and morning and lunch recesses, but low (10%) in the after-school period. On factor analysis there were differences in PA patterns between the school period and the after-school period. The students who spent their time in the playground logged more MVPA time and less sedentary time (≤1.5 MET) than those who did not spend their time in the playground. CONCLUSION: Activities before school, and in the morning and lunch recesses influenced daily PA, and were different from after-school PA. Close attention to these periods may help in defining PA parameters during free time at school for PA interventions in children.

Physical activity modifies the FTO effect on body mass index change in Japanese adolescents.

BACKGROUND: Evidence of the effects of fat mass and obesity-associated (FTO) variation and long-term effects of physical activity (PA) on adiposity in adolescents is largely scarce. This study therefore investigated whether PA modulates the effects of the FTO on body mass index (BMI) changes in Japanese adolescents between the ages of 13 and 18 years. METHODS: Data on 343 subjects (156 boys; 187 girls) who were enrolled in 2006 and 2007 at schools in Shunan City, Japan, were collected. Genotyping (rs1558902) was conducted, and anthropometry and blood test results were recorded for subjects in the eighth grade. A second survey involving self-reporting of anthropometry was conducted when the subjects were in the 12th grade. PA was estimated using the International Physical Activity Questionnaire. BMI and the standard deviation score for BMI (BMI-SDS) were calculated. BMI changes and BMI-SDS changes were compared between FTO genotypes using a multivariate model. RESULTS: The effect of the interaction between PA and the FTO genotype on BMI changes was significant in boys but not in girls. In boys, PA had a significant negative influence on BMI-SDS changes in those with the AA genotype and a significant positive influence on BMI and BMI-SDS changes in those with the TT genotype. CONCLUSION: The influence of PA on BMI change and BMI-SDS change varies on the basis of genotype. PA modified the effect of FTO on BMI change in Japanese boys.

Placing Salt/Soy Sauce at Dining Tables and Out-Of-Home Behavior Are Related to Urinary Sodium Excretion in Japanese Secondary School Students.

We investigated whether home environment, salt knowledge, and salt-use behavior were associated with urinary sodium (Na) excretion in Japanese secondary school students. Students (267; mean age, 14.2 years) from Suo-Oshima, Japan, collected three overnight urine samples and completed a salt environment/knowledge/behavior questionnaire. A subset of students (n = 66) collected, on non-consecutive days, two 24 h urine samples, and this subset was used to derive a formula for estimating 24 h Na excretion. Generalized linear models were used to examine the association between salt environment/knowledge/behavior and Na excretions. Students that had salt or soy sauce placed on the dining table during meals excreted more Na than those that did not (pfor trend < 0.05). A number of foods to which the students added seasonings were positively associated with Na excretion (pfor trend = 0.005). The students who frequently bought foods at convenience stores or visited restaurants excreted more Na in urine than those who seldom bought foods (pfor trend < 0.05). Knowledge about salt or discretionary seasoning use was not significantly associated with Na excretion. The associations found in this study indicate that home environment and salt-use behavior may be a target for a public health intervention to reduce salt intake of secondary school students.

Association between objectively evaluated physical activity and sedentary behavior and screen time in primary school children.

BACKGROUND: Even when meeting guidelines for physical activity (PA), considerable sedentary time may be included. This study in primary school children investigated the relationships between objectively evaluated sedentary and PA times at different intensities using triaxial accelerometry that discriminated between ambulatory and non-ambulatory PA. The relationships between subjectively evaluated screen time (i.e. time spent viewing television and videos, playing electronic games, and using personal computers) and objectively evaluated sedentary and PA times were examined. METHODS: Objectively evaluated sedentary and PA times were assessed for 7 consecutive days using a triaxial accelerometer (Active style Pro: HJA-350IT) in 426 first to sixth grade girls and boys. Metabolic equivalents [METs] were used to categorize the minutes of sedentary time (≤1.5 METs), light PA (LPA, 1.6-2.9 METs), moderate-to-vigorous PA (MVPA,  ≥3.0 METs) and vigorous PA (VPA,  ≥6.0 METs). The physical activity level (PAL) was calculated using the mean MET value. Subjectively evaluated screen time behaviors were self-reported by participants and parents acting together. The associations between PA and sedentary and screen time variables were examined using partial correlation analyses. RESULTS: After adjustment for age, body weight and wearing time, objectively evaluated sedentary time correlated strongly with non-ambulatory and total LPA and PAL, moderately with ambulatory LPA, non-ambulatory or total MVPA, and weakly with ambulatory MVPA, ambulatory, non-ambulatory or total VPA. Subjectively evaluated screen time was not associated significantly with objectively evaluated sedentary and PA times or PAL. On average, each reduction of 30 min in daily sedentary time was associated with 6 or 23 min more of MVPA or LPA, respectively. CONCLUSIONS: These findings show that higher daily sedentary time may be compensated mainly by lower LPA, while the association between sedentary time and MVPA was moderate. Therefore, improving MVPA and reducing sedentary time are important in primary school children.

Twenty-four-hour urinary sodium and potassium excretion and associated factors in Japanese secondary school students.

Data on the sodium and potassium intake using dietary records among schoolchildren are sorely lacking in the Japanese literature. Some evidence indicates that sodium and potassium intake has been correctly measured, but information concerning these associated factors is scarce. The 24-h urine samples and first morning voiding (overnight) samples were collected twice from 68 secondary schoolchildren in Suo-Oshima Town, Japan. Sodium, potassium and creatinine concentrations were analyzed. Body height and weight were measured, and menstruation and physical activity were assessed via questionnaires. We analyzed the 24-h samples with a >20-h collecting period and no missed voiding. The 24-h sodium excretion was 163.2±36.8 and 149.8±45.1 mmol per 24 h for the boys and girls, respectively. Considering daily habits and loss from sweat, intake was assumed to be 10.6±1.2 and 10.0±2.4 g per day for the boys and girls, respectively. The 24-h potassium excretion was 43.4±10.8 and 45.8±14.4 mmol per 24 h for the boys and girls, respectively. Estimated usual potassium intake was 2195±401 and 2330±630 mg per day for the boys and girls, respectively. Sodium excretion was associated with sodium and potassium concentrations in overnight urine samples and physical activity. Potassium excretion was associated with height and physical activity. We described daily sodium and potassium excretion in Japanese secondary schoolchildren. Excretion was associated more with physical activity than with bodyweight. Therefore, the estimation methods used in adults are not applicable for use in adolescents.

Dietary Fiber Consumption Decreases the Risks of Overweight and Hypercholesterolemia in Japanese Children.

AIMS: It remains inconclusive whether high dietary fiber intake decreases the risk of obesity, hypercholesterolemia or high blood pressure during childhood. Therefore, this study investigated the relationships of dietary fiber intake with weight status and related clinical parameters among Japanese children. METHODS: We analyzed the data of 5,600 subjects aged 10-11 years, between 2006 and 2010. Fiber intake was assessed using the Brief-type Diet History Questionnaire. Body height and weight and blood pressure were measured. Serum levels of total cholesterol, low- and high-density lipoprotein cholesterol and triglycerides were analyzed. Fiber intake was categorized into quintiles, and multivariate models were used to adjust for lifestyle factors. RESULTS: Total fiber intake decreased the risks of overweight and high total cholesterol (OR Quintile 5 vs. Quintile 1 overweight: 0.71 for boys, 0.40 for girls; total cholesterol: 0.60 for boys, 0.66 for girls). Water-soluble fiber intake was associated with a lower risk of high blood pressure, although the ORs were not significant. CONCLUSIONS: Increasing the dietary fiber intake in Japanese children may have favorable effects on overweight and hypercholesterolemia.