Narumi Nagai

The body mass index (BMI), defined as weight in kilograms divided by height in meters squared, has been widely used to assess thinness and obesity in all age groups, including children and adolescents. However, the validity and utility of BMI as a reliable measure of nutritional health have been questioned. This study discusses the mathematical conditions that support the validity of BMI based on population statistics. Here, we propose a condition defined as allometric uni-scaling to ensure the validity of BMI as an objective height-adjusted measure. Any given centile curve, including the median curve, in a weight-for-height distribution should be approximated using power-law functions with the same scaling exponent. In contrast, when the scaling exponent varies depending on the position of the centile curve, it is called allometric multi-scaling. By introducing a method for testing these scaling properties using quantile regression, we analyzed a large-scale Japanese database that included 7,863,520 children aged 5-17 years. We demonstrated the remarkable multi-scaling properties at ages 5-13 years for males and 5-11 years for females, and the convergence to uni-scaling with a scaling exponent close to 2 as they approached 17 years of age for both sexes. We confirmed that conventional BMI is appropriate as an objective height-adjusted mass measure at least 17 years of age, close to adulthood, for both males and females. However, the validity of BMI could not be confirmed in younger age groups. Our findings indicate that the growth of children’s weight-for-height relation is much more complex than previously assumed. Therefore, a single BMI-type formula cannot be used to assess thinness and obesity in children and adolescents.

Background Precision in evaluating underweight and overweight status among children and adolescents is paramount for averting health and developmental issues. Existing standards for these assessments have faced scrutiny regarding their validity. This study investigates the age and height dependencies within the international standards set by the International Obesity Task Force (IOTF), relying on body mass index (BMI), and contrasts them with Japanese standards utilizing the percentage of overweight (POW). Method We scrutinized a comprehensive database comprising 7,863,520 children aged 5–17 years, sourced from the School Health Statistics Research initiative conducted by Japan's Ministry of Education, Culture, Sports, Science, and Technology. Employing the quantile regression method, we dissected the structure of weight-for-height distributions across different ages and sexes, quantifying the potentially biased assessments of underweight and overweight status by conventional criteria. Results Applying IOFT criteria for underweight assessment revealed pronounced height dependence in males aged 11–13 and females aged 10–11. Notably, a discernible bias emerged, wherein children in the lower 25th percentile were classified as underweight five times more frequently than those in the upper 25th percentile. Similarly, the overweight assessment displayed robust height dependence in males aged 8–11 and females aged 7–10, with children in the lower 25th percentile for height deemed obese four or five times more frequently than their counterparts in the upper 25th percentile. Furthermore, using the Japanese POW criteria for assessment revealed significant age dependence in addition to considerably underestimating the percentage of underweight and overweight cases under the age of seven. However, the height dependence for the POW criterion was smaller than the BMI criterion, and the difference between height classes was less than 3-fold. Conclusion Our findings underscore the intricacies of age-dependent changes in body composition during the growth process in children, emphasizing the absence of gold standards for assessing underweight and overweight. Careful judgment is crucial in cases of short or tall stature at the same age, surpassing sole reliance on conventional criteria results.

Background We have previously reported that female patients with nontuberculous mycobacterial lung disease (NTM-LD) are thinner and eat less than healthy controls. Therefore, we hypothesized that their thinness is associated with body size misperception. The aim of this study was to clarify whether patients’ body size perception (BSP) is associated with body mass index (BMI) independent of potential confounders. Methods In this cross-sectional study, we assessed 81 outpatients for BSP using the Japanese version of Body Image Scale, body composition, dietary intake, and biochemical markers. As a control, we used BSP and self-reported anthropometric data from 111 healthy women collected via a web survey. First, BSP and BMI were compared between the patients and the controls. Second, patient data was compared between patients who overestimated their body size (OE, n = 31) and a control who did not (Non-OE, n = 50). Multiple regression analysis was performed to clarify the association between BSP (independent variable) and BMI (dependent variable), adjusting for potential confounders, such as age, disease duration, and nutritional factors. Results There was a negative correlation between body size distortion and BMI in both patients and controls (p < 0.001, both). In interpatient comparisons, the OE group had significantly lower BMI and body fat percentage (p < 0.001, both), normalized energy (p = 0.037), and protein (p = 0.013) intakes, and significantly greater weight loss from age 20 (p = 0.003) than the Non-OE group. Multiple regression analysis revealed that overestimation of body size was associated with lower BMI independent of confounders, such as longer disease history, longitudinal weight loss, and nutritional factors. Conclusion These findings suggest that body size distortion is an etiological factor for lower BMI in female patients with NTM-LD. Thus, it may be important to understand the patient’s body image when providing dietary advice.

Recent reports have associated the use of social networking sites (SNS) with the drive for thinness in young women; however, its influence on their actual body shape and eating behaviors (EB) remains unclear. We aimed to examine the effect of SNS use on body mass index (BMI), body image (BI), and EB in young women. Participants included 196 healthy women (20-29 years) who answered questions about their SNS use, height, weight, BI and EB via a web-based survey. First, the correlation between time spent on SNS and each variable was determined. Participants were then divided into quartiles according to the duration of daily SNS use as long (≥3 h, n = 52) and short (<1 h, n = 54), and the data were then compared between the groups. Correlation analysis showed that the longer the duration of daily SNS use, the significantly lower the BMI, the use of nutrition labels, and the frequency of consumption of milk and dairy products. The long group had significantly lower BMI and ideal BI than the short group. The results suggest that spending more time on SNS in young women may be associated with thinner actual and ideal body shapes and poorer access to health information and healthy foods.

Abstract Background In women, slender body habitus has been reported to be one of the predisposing factors underlying the development and poor prognosis of non-tuberculous mycobacterial lung disease (NTM-LD). Given the lack of nutritional data contributing to treatment strategies, we aimed to clarify the nutritional status of female patients with NTM-LD and its association with disease severity. Methods In this single-center observational study, we enrolled 81 female outpatients with NTM-LD. Data on healthy women of similar ages were selected from our previous survey data and categorized as controls. First, we compared anthropometric and dietary survey data between patients and controls. Second, after the patients were categorized into relatively mild (mild, n = 40) and relatively severe groups (severe, n = 41) based on pulmonary X-ray-image finding scores, body composition, nutritional intake, and biochemical markers were compared between the groups. To identify nutritional factors associated with disease severity, logistic regression analyses were performed. Results Compared with controls, patients with NTM-LD had significantly lower energy intake, body mass index, body fat, and skeletal muscle mass (all p &lt; 0.001). Compared with the mild group, the severe group had significantly lower skeletal muscle mass (p = 0.037), albumin (p = 0.029), transthyretin (prealbumin) (p = 0.002), retinol-binding protein (p = 0.011), and hemoglobin (p = 0.001); however, no between-group differences were observed in energy or nutrient intake. Logistic analyses revealed that transthyretin (p = 0.025) and hemoglobin (p = 0.003) levels were independent factors associated with disease severity. Conclusions This is the first study to comprehensively report the association between NTM-LD severity and nutritional status, including body composition, nutrient intake, and biomarkers. The results suggest that initiating nutritional therapy from the mild stage of the disease to prevent undernutrition is warranted.

For athletes, it is important to acquire lean body mass (LBM) involving the skeletal muscle mass during their growth periods; however, the influence of chronotype on LBM gain remains unclear. We therefore aimed to investigate whether chronotype, sleep-wake cycle on weekdays (SWC-W), and their interaction contribute to LBM gain among adolescent male athletes in a 4-month intervention study. The participants were 45 male high-school baseball players. The intervention, including exercise menu (running and muscle strength training) and nutritional education, was conducted during a 4-month period of season-off training. The chronotype, body composition, lifestyle, and dietary intake were investigated before intervention (baseline) and after 4 months. Among the participants [Morningness (n = 14), Eveningness (n = 15), Intermediate (n = 16); ME score based on the Morningness/Eveningness Scale for Children (MES-C)], the midpoint of sleep on weekdays (MSW) was calculated in the "Morningness" and "Eveningness" participants, respectively. They were divided into 4 groups based on a match/mismatch with the chronotype: Type M-match (n = 8), Type M-mismatch (n = 6), Type E-match (n = 7), and Type E-mismatch (n = 8) groups. The data were compared among the 4 groups. Moreover, multiple regression analysis was conducted using an increase (kg) LBM gain as a response variable. When comparing the data between the "Morningness" and "Eveningness" participants, there were no differences in nutrient intake, the duration of training, or each parameter of body composition (per body weight) at baseline or after 4 months. There were also no differences in the rates of change in the body weight or each parameter of body composition. In groups in which the chronotype was consistent with the SWC-W (the Type M-match and Type E-match groups), the LBM gain were slightly greater than in the Type M-mismatch and Type E-mismatch groups (Type M-match: 3.5 ± 2.0 kg, Type M-mismatch: 1.6 ± 1.7 kg, Type E-match: 3.4 ± 2.2 kg, and Type E-mismatch: 1.2 ± 1.8 kg, p = .057). Multiple regression analysis revealed that an extent of the LBM gain was associated with a match between the chronotype and SWC-W (ß = 0.37, p = .030), independent of a long duration of training (ß = 0.52, p = .004). The results suggested that training-related LBM gain is associated with interactions between the chronotype and SWC-W in adolescent male athletes.Abbreviations: LBM: Lean body mass; SWC-W: Sleep-wake cycle on weekdays; ME score: Morningness-eveningness score; MES-C: Morningness/Eveningness Scale for Children; MSW: Midpoint of sleep on weekdays; MSF: Midpoint of sleep on free days; MSFsc: Midpoint of sleep on free days corrected for sleep debt accumulated through weekdays.

OBJECTIVE: Low birth weight (LBW) is a major public health issue as it increases the risk of noncommunicable diseases throughout life. However, the genome-wide DNA methylation patterns of full-term LBW infants (FT-LBWs) are still unclear. This exploratory study aimed to analyze the DNA methylation differences in FT-LBWs compared with those in full-term normal birth weight infants (FT-NBWs) whose mothers were nonsmokers and had no complications. Initially, 702 Japanese women with singleton pregnancies were recruited. Of these, four FT-LBWs and five FT-NBWs were selected as references for DNA methylation analysis, and 862,260 CpGs were assessed using Illumina Infinium MethylationEPIC BeadChip. Gene ontology enrichment analysis was performed using DAVID v6.8 software to identify the biological functions of hyper- and hypomethylated DNA in FT-LBWs. RESULTS: 483 hyper-differentially methylated genes (DMGs) and 35 hypo-DMGs were identified in FT-LBW promoter regions. Hyper-DMGs were annotated to 11 biological processes; "macrophage differentiation" (e.g., CASP8), "apoptotic mitochondrial changes" (e.g., BH3), "nucleotide-excision repair" (e.g., HUS1), and "negative regulation of inflammatory response" (e.g., NLRP12 and SHARPIN). EREG was classified into "ovarian cumulus expansion" within the "organism growth and organization" category. Our data imply that LBW might be associated with epigenetic modifications, which regulate the immune system and cell maturation.

AIM: Small-for-gestational-age (SGA) status has negative health consequences in neonates and later life. Low socioeconomic status (SES) is a reported risk factor for adverse birth outcomes, such as SGA and preterm birth (PTB). The present study investigated whether maternal SES is associated with adverse outcomes in Japanese pregnant women. METHODS: Retrospective data were collected for 1970 Japanese women with singleton pregnancies who delivered between January 2007 and December 2011 at a single center: low SES group (n = 197); and controls (n = 1773). Low SES was defined according to the criteria of the Japanese pregnant-childbirth hospitalization support policy system. RESULTS: The low SES group included a significantly higher proportion of young women, women with single marital status, greater parity, pre-pregnancy smoking and a lack of regular employment (P < 0.001, respectively). The crude odds ratio (OR) for the association between low maternal SES and SGA was 1.80 (95% confidence interval [CI] 1.15-2.82, P = 0.010). After adjustment for baseline maternal age, parity, body mass index, smoking and gestational weight gain, the adjusted OR for the association between low maternal SES and SGA was 1.92 (95% CI 1.17-3.17, P = 0.010). No significant association was found between maternal SES and PTB. CONCLUSION: The present results suggest that low maternal SES is associated with SGA births in the Japanese population. Mitigation of low maternal SES could be urgent public health to prevent disadvantage birth outcome.

Being born with large birthweight is considered as a risk of non-communicable diseases later in life. However, it is not fully understood what kind of maternal dietary intake during pregnancy affect large birthweight. Therefore, we examined the association of dietary intakes and its changes during pregnancy with large-for-gestational-age (LGA) births in Japanese pregnant women. In the prospective study, 245 pregnant women who visited Kyoto Medical Center were enrolled. Nutrition survey using brief-type self-administered diet history questionnaire (BDHQ) at all trimester was completed in 171 pregnant women. Based on birthweight and gestational age, participants were divided into three groups, such as small-for-gestational-age (<10th, SGA, n=17), appropriate-for-gestational-age (≥10th and <90th, AGA, n=144), and LGA (≥90th, n=10) groups. Compared with those without LGA births, mothers with LGA births showed: 1) greater weight gain during pregnancy (LGA: 14.0±3.2 kg, AGA: 9.9±3.9 kg, SGA: 8.4±3.1 kg, p<0.05); 2) higher energy intake throughout pregnancy (LGA: 310±368 kcal, AGA: 7±490 kcal, SGA: -97±293 kcal, ptrend<0.05); 3) larger changes in plant oil and sucrose consumptions from the 1st to 2nd trimester, probably due to the results of greater consumption of bread, Western confectionery, Japanese confectionery, and mayonnaise and dressing during the same period (ptrend<0.05, respectively). Our results suggest that higher energy intake throughout pregnancy, as well as greater consumption of plant oil and sucrose from the first to second trimester could be associated with LGA births.

Maslinic acid, derived from olive fruit, reduces pro-inflammation cytokines, which are involved in muscle fiber atrophy. Therefore, the maslinic acid ingestion may enhance the muscular response to resistance training through anti-inflammatory action. We therefore conducted a parallel, double-blind, randomized, placebo-controlled trial that examined whether a combination of maslinic acid supplementation and resistance training improve mobility functions in community-dwelling elderly persons. Over a 12-week period, 36 participants underwent moderate resistance training and are assigned to the maslinic acid supplementation (n = 17, 60 mg/day) or the placebo (n = 19) group. At baseline and at 12-weeks, we assessed body composition, grip strength, walking speed, leg strength, mobility functions, and knee pain scores. Following the 12-weeks, skeletal muscle mass, segmental muscle mass (right arm, left arm, and trunk) and knee pain score of the right leg were significantly improved in the maslinic acid group, while there was no change or parameters had worsened in the placebo group. Grip strength of the better side significantly increased only in the maslinic acid group. These results suggest that maslinic acid supplementation combined with moderate resistance training may increase upper muscle mass and grip strength, and reduce knee pain, could be effective for preventing mobility-related disability in elderly persons. Clinical trial registration number: UMIN000017207.

Background: Polycystic ovary syndrome (PCOS) is a common endocrine disorder among reproductive-aged women. While PCOS is associated with an increased risk of obesity and insulin resistance, little is known regarding the prevalence of and risk factors for nonalcoholic fatty liver disease (NAFLD) among Japanese women with PCOS. We estimated the prevalence of and risk factors for elevated liver enzymes, as the index of NAFLD, in Japanese women with PCOS. Methods: We retrospectively reviewed 102 reproductive-aged women who visited the Department of Gynecology, Kyoto Medical Center in Japan from January 2000 to September 2016. Inclusion criterion was confirmed diagnosis of PCOS using International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10) codes. Exclusion criteria were women with a history of liver diseases, missing body mass index (BMI) and serum alanine aminotransferase (ALT) data, and pregnancy. Data regarding age; BMI; and levels of blood glucose, serum lipid, liver enzymes, and sex hormones were obtained from medical records. Elevated liver enzymes was defined as ALT > 19 IU/L. Optimal cutoffs for risk factors for elevated liver enzymes were calculated to determine predictors of elevated liver enzymes using area under the curve (AUC) by receiver-operating characteristics (ROC). Results: The prevalence of elevated liver enzymes was 33.3%. BMI was significantly higher in PCOS patients than in those without elevated liver enzymes (25.3 vs. 20.7 kg/m2, P < 0.05). ROC analyses were performed using BMI and blood glucose and testosterone levels because BMI and blood glucose showed differences between the groups and testosterone is related to fatty liver. AUC of the model including BMI and blood glucose and testosterone levels was 0.861 (sensitivity, 66.7%; specificity, 100%). Conclusions: These findings suggest that elevated liver enzymes are common in women with PCOS. An algorism using BMI and blood glucose and testosterone levels might be useful to determine elevated liver enzymes in women with PCOS. Our finding may be useful for the study of NAFLD among Japanese women with PCOS since several previous studies have indicated elevated liver enzymes to be related to the potential presence of NAFLD. Further examination, including abdominal ultrasonography and/or liver biopsy data, is required to confirm these results.

Physical exercise exerts favourable effects on brain health and quality of life of the elderly; some of these positive health effects are induced by the modulation of microbiota composition. We therefore conducted a randomised, double blind, placebo-controlled trial that assessed whether a combination of Bifidobacterium spp. supplementation and moderate resistance training improved the cognitive function and other health-related parameters in healthy elderly subjects. Over a 12-week period, 38 participants (66-78 years) underwent resistance training and were assigned to the probiotic Bifidobacterium supplementation (n=20; 1.25×1010 cfu each of Bifidobacterium longum subsp. longum BB536, B. longum subsp. infantis M-63, Bifidobacterium breve M-16V and B. breve B-3) or the placebo (n=18) group. At baseline and at 12 weeks, we assessed the cognitive function, using the Japanese version of the Montreal Cognitive Assessment instrument (MoCA-J); modified flanker task scores; depression-anxiety scores; body composition; and bowel habits. At 12 weeks, the MoCA-J scores showed a significant increase in both the groups, while the flanker task scores of the probiotic group increased more significantly than those of the placebo group (0.35±0.9 vs -0.29±1.1, P=0.056). Only the probiotic group showed a significant decrease in the depression-anxiety scores (5.2±6.3 to 3.4±5.5, P=0.012) and body mass index (24.0±2.8 to 23.5±2.8 kg/m2, P<0.001), with a significant increase in the defecation frequency (5.3±2.3 to 6.4±2.3 times/5 days, P=0.023) at 12 weeks. Thus, in healthy elderly subjects, combined probiotic bifidobacteria supplementation and moderate resistance training may improve the mental condition, body weight and bowel movement frequency.