OBJECTIVE:To analyze epidemiological characteristics and temporal changes in the prevalence of thinness, anemia, overweight and obesity among primary and secondary school students in Beijing between 2015 and 2019. METHODS:The survey participants were students who participated in the Beijing Primary and Secondary School Students' Nutrition and Health Status Monitoring in 2015 and 2019. A multistage stratified cluster random sampling method was employed to select 14, 126 students in grades 1, 3, 5, and 7 from 56 schools across 7 districts of Beijing for height, weight, and hemoglobin measurements, with classifications of thinness, anemia, overweight, and obesity determined using diagnostic thresholds from Chinese health industry standards Growth Standard for Children Under 7 Years (WS/T 423-2022), Screening Standard for Malnutrition of School-age Children and Adolescents (WS/T 456-2014), Screening Standard for Overweight and Obesity among School-age Children and Adolescents (WS/T 586-2018), and Method for Anemia Screening in Population (WS/T 441-2013); malnutrition prevalence among demographic subgroups was described using constituent ratios with between-year (2015 vs.2019) differences compared by χ2 test, while generalized linear mixed models analyzed changes in malnutrition prevalence adjusted for age, sex, and residential area. RESULTS:The survey revealed that among Beijing students aged 6-14 years, the overall thinness prevalence increased from 378 cases (5.25%) in 2015 to 435 cases (6.28%) in 2019, with statistically significant increases observed among girls (171 (4.88%) vs.208 (6.08%)), suburban students (197 (4.41%) vs.271 (6.20%)), and the 6-9 age group (181 (5.09%) vs.242 (6.81%)) (P<0.05); simultaneously, the overall anemia detection rate decreased from 197 (2.74%) in 2015 to 131 (1.89%) in 2019, with significant declines among boys (97 (2.63%) vs.58 (1.65%)), suburban students (166 (3.72%) vs.110 (2.52%)), and the 6-9 age group (161 (4.52%) vs.79 (2.22%)), while conversely increasing in the 10-14 age group (36 (0.99%) vs.52 (1.54%)) (all P<0.05); both overweight prevalence (1137 (15.80%) in 2015 vs.1106 (15.96%) in 2019) and obesity prevalence (1410 (19.60%) in 2015 vs.1367 (19.72%) in 2019) showed no statistically significant differences overall or within any demographic subgroups; generalized linear mixed model analysis confirmed increased thinness risk in 2019 (OR=1.21, 95% CI 1.05-1.40), decreased anemia risk (OR=0.67, 95% CI 0.53-0.83), and non-significant changes in overweight/obesity prevalence between survey years. CONCLUSION:The thinness prevalence among Beijing students aged 6-14 years in 2019 had increased compared to 2015 levels, while anemia rates have shown a declining trend during the same period, the prevalence of overweight and obesity remained relatively stable overall. These indicators displayed multidimensional differentiation patterns across gender, region, and age.
OBJECTIVE:To investigate the relationship between the Chinese visceral adiposity index (CVAI), bone mineral content (BMC), and serum osteocalcin (OC) and type I collagen cross-linked C-terminal peptide (CTX) levels in Yinchuan middle school students. METHODS:A total of 1603 students aged 12-18 years in Yinchuan City were selected as study subjects with a mean age of (14.99±1.51) years old in 2017-2023 by stratified clustering sampling, including 915(57.1%) boys, 1149(71.7%)Han, 201(12.5%)Hui and 191(11.9%) from other ethnic groups. Height and weight were measured, and total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) were measured. The serum osteocalcin and type I collagen cross-linked C-terminal peptide were measured by enzyme linked immunosorbent assay (ELISA). Regression models combined with restricted cubic spline were used to analyze the relationship between CVAI and low bone mass and low bone metabolism markers among middle school students in Yinchuan City, and receiver operating characteristic(ROC) curves were used to analyze the effect of their assessment on low bone mass. RESULTS:After adjusting for confounding factors of gender, age, smoking, alcohol consumption, physical activity and outdoor activity hours, the risk of low bone mass was lower in the Q4 of CVAI than in the Q1(OR=0.03, 95%CI 0.01-0.07), and the result were similar after stratification by gender (P<0.05); the risk of low OC in the Q4 of CVAI was higher than that in the Q1(OR=1.98, 95%CI 1.36-2.88), while the risk of low CTX was lower than that of Q1(OR=0.52, 95%CI 0.36-0.75, P<0.05). A linear dose-response relationship was observed between CVAI and low bone mass and low CTX (Poverall trend<0.05, Pnonlinearity>0.05), while a nonlinear dose-response relationship was found between CVAI and low OC(Poverall trend<0.05, Pnonlinearity<0.05). The ROC curve analysis revealed that CVAI had the best diagnostic performance for low bone mass (AUC=0.87, 95%CI 0.85-0.90, P<0.05). CONCLUSION:Increased CVAI can reduce the risk of low bone mass and low CTX, and increase the risk of low OC in Yinchuan middle school students.
OBJECTIVE:To investigate the effects of Pediococcus acidilactici fermentation on mulberry juice quality. METHODS:Fresh mulberry juice was used as the raw material and inoculated with P. acidilactici strain 003W to establish a fermentation system. After fermentation at 37 ℃ for 48 h, the active components (total phenolics and anthocyanins), physicochemical indexes (pH, total acid content, reducing sugar content), antioxidant activity (DPPH and ABTS+ radical scavenging rates), and electronic tongue flavor characteristics (sourness, astringency, richness, etc. ) were evaluated before and after fermentation. RESULTS:The result showed that after fermentation, the total phenolic content increased from 11.01 mg GAE/mL to 13.41 mg GAE/mL, and the anthocyanin content increased from 0.60 mg RE/mL to 0.79 mg RE/mL. The pH value decreased from 5.70 to 4.34; the total acid content (expressed as lactic acid) increased from 4.10 g/L to 12.24 g/L; and the reducing sugar content (expressed as glucose) decreased from 85.00 mg/mL to 75.00 mg/mL. The DPPH free radical scavenging rate and ABTS+ free radical scavenging rate reached 40.08% and 49.87% from 18.00% and 28.00%(P<0.05). Electronic tongue analysis indicated that the sourness and richness of fermented mulberry juice were enhanced, while the astringency was significantly reduced, resulting in a more harmonious flavor profile. CONCLUSION:This study demonstrates that fermentation by P. acidilactici 003W effectively enhances the content of active components, antioxidant capacity, and flavor characteristics of mulberry juice, offering a scientific foundation for developing high-value probiotic mulberry beverages.
OBJECTIVE:To analyze the characteristics and changes in screen time among students aged 6-14 years in Beijing in 2015 and 2019. METHODS:A multistage cluster sampling approach was adopted. A survey on after-school screen time was conducted among students in grades 1, 3, 5, and 7 (first year of junior high school) in 7 districts of Beijing in 2015 and 2019, using the Nutrition and Health Status Questionnaire developed by the Beijing Center for Disease Prevention and Control. A total of 4152 primary and secondary school students were surveyed in 2015, and 4202 in 2019. The Mann-Whitney U test and chi-square test were employed to analyze differences in daily average screen time and the prevalence of exceeding the daily screen time limit among respondents with different demographic characteristics. Using a generalized linear mixed model (GLMMs) to analyze the association between different years, gender, age, residential areas, and whether screen time exceeds the limit. RESULTS:Survey result showed that the median screen time of respondents was 54 (31, 84) min/d in 2015 and 41 (26, 69) min/d in 2019, representing a decrease of 13 min/d (P<0.01). The prevalence of exceeding the daily screen time limit (≥2 h/d) was 10.06% (403/4005) in 2015 and 5.01% (203/4052) in 2019, a reduction of 5.05 percentage points (P<0.01). Compared with 2015, the daily average screen time (school days, weekends, and the entire week) of respondents across different genders, age groups, and regions all decreased in 2019 (male：Z=-6.95, Z=-9.37, Z=-9.55；female：Z=-4.63, Z=-10.77, Z=-8.94；6-9 years：Z=-4.12, Z=-8.38, Z=-7.06；10-14 years：Z=-7.63, Z=-11.89, Z=-11.63；urban：Z=-5.37, Z=-10.48, Z=-9.11；suburban：Z=-6.13, Z=-10.02, Z=-9.62；P <0.01). GLMMs analysis revealed that the daily average screen time exceeding rate among survey subjects in 2019 was lower than in 2015 (β = -0.74, OR=0.48，95% CI 0.40-0.57). Compared with their counterparts with the same characteristics, respondents who were male (β = 0.26, OR=1.29, 95%CI 1.09-1.53), aged 10-14 years(β=0.67，OR=1.95，95%CI 1.64-2.32), and residing in suburban areas (β=0.57, OR=1.77, 95%CI 1.47-2.12) had a significantly higher rates of excessive screen time (P<0.01). CONCLUSION:The daily average screen time and prevalence of excessive screen time among primary and secondary school students in Beijing decreased significantly overall in 2019 compared with 2015. However, male students, age 10-14 years, and those residing in suburban areas consistently had higher screen time and a higher prevalence of excessive screen time than their counterparts within the same categories.
OBJECTIVE:An analytical method for the determination of 32 pesticide residues in human urine was established using amino multi-walled carbon nanotubes (NH2-MWCNTs)-based dispersive solid-phase extraction combined with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). METHODS:25% saturated sodium chloride solution was added to precipitate protein in the urine. The pH was adjusted to 5 using 20 mmol/L ammonium acetate solution. The target analytes were adsorbed onto amino multi-walled carbon nanotubes, followed by desorption with acetonitrile. Finally, the extract was analyzed by UPLC-MS/MS. RESULTS:Good linearity for the 32 pesticides was observed within the concentration range of 1-100 μg/L, with correlation coefficients (r) all above 0.999. Fortified at three concentration levels (4, 40, and 200 μg/L, n=6), average recoveries were obtained in the range of 91.2%-110.0%, with relative standard deviations ranging from 1.1%-4.6%. The limits of detection and quantification were determined to be 0.003-0.03 μg/L and 0.01-0.1 μg/L, respectively. The adsorption process of the 32 pesticides onto the NH2-MWCNTs was found to be well described by the pseudo-second-order kinetic model and the Langmuir isotherm model. CONCLUSION:This method is simple and rapid to operate, accurate, and highly sensitive, enabling the rapid detection of 32 pesticide residues in human urine.
