Evidence linking caries in primary dentition and children’s anthropometric measures is contradictory. We aimed to evaluate the prevalence of primary dental caries and its relationship with body mass index (BMI) among 7-9 years old school children in urban Guangzhou, China. This cross-sectional study enrolled 32,461 pupils (14,778 girls and 17,683 boys) aged 7-9 years from 65 elementary schools in Guangzhou. Dental caries was detected according to criteria recommended by the World Health Organization (WHO). The total mean decayed, missing or filled teeth (dmft) of primary dentition were assessed. Weight and height were measured and BMI was calculated. Children were classified into underweight, normal weight, overweight and obesity groups by BMI based on Chinese criteria. Z-score of BMI-for-age (BAZ) was calculated by WHO standardized procedure. Multivariable odds ratios (ORs) and 95 % confidence intervals (CIs) were calculated using logistic regression. Restricted cubic spline regression was applied to evaluate the shape of the relationship between BAZ and primary dental caries. The prevalence of primary dental caries was 30.7 % in total sample. Regarding dmft values, the mean ± standard deviation (SD) in the combined sample were 1.03 ± 2.05 in boys and 0.93 ± 1.92 in girls. Both indices decreased by age. Compared with normal BMI group, children in overweight and obesity groups have 27 % (OR = 0.73, 95 % CI: 0.66-0.81, P < 0.0001) and 34 % (OR = 0.66, 95 % CI: 0.59-0.74, P < 0.0001) lower odds for the presence of primary dental caries after adjustment for age and gender, respectively. Although in general, increased BAZ was associated with decreased risk of dental caries, full-range BAZ was associated with dental caries in an A-shaped manner with a zenith at around -1.4. Higher BMI was associated with lower odds of caries; overweight and obese children were more likely to be primary dental caries free among 7-9 years in Guangzhou, China.

Although obesity is considered osteoprotective, the effects of body fat and fat distribution on bone tissue after adjusting for the effects of body weight remain uncertain. This study evaluated the relationships between fat mass, fat distribution, and bone mineral status beyond its weight-bearing effect. We recruited 466 children aged 6–10 years in China. Dual-energy X-ray absorptiometry was used to determine the bone mineral density (BMD) and bone mineral content (BMC) in the total body and total body less head (TBLH), as well as the fat mass (FM) and percentage fat mass (%FM) of the total and segmental body. Weight-adjusted measures of FM and %FM were derived using the residual method. After adjusting for the effects of covariates, we observed statistically significant, dose-dependent negative relationships between the TBLH·BMD/BMC and various weight-adjusted measures of body fat (p for trend: <0.001–0.038). For each standard deviation increment in the weight-adjusted total body, TBLH, trunk and limbs, the size-adjusted BMC decreased approximately 9.44, 9.28, 8.13, and 6.65 g in boys, respectively, and by approximately 13.74, 13.71, 7.84, and 12.95 g in girls, respectively. Significant inverse associations between FM accumulation in the total body and most body parts with the BMD/BMC were observed in both boys and girls after adjusting for weight and potential confounders.

Telomere length (TL) serves as a marker of cellular senescence and appears to plateau between the age of 4 y and young adulthood, after which the gut microbiota are supposed to be established. However, scarce data are available regarding the correlation between gut microbiota composition and TL in the pediatric population. We aimed to investigate whether the gut microbiota and the concentrations of SCFAs in feces are associated with leukocyte TL in children. In total, 401 children aged 6–9 y from Guangzhou were enrolled in this cross-sectional study. qPCR was used to determine relative TL in peripheral blood leukocytes. The gut microbiota was characterized by 16S ribosomal RNA amplicon sequencing and the fecal concentrations of total SCFAs and SCFA subtypes were determined using HPLC. The multivariate methods with an unbiased variable selection (MUVR) algorithm and partial least square models were used to select predictable operational taxonomic units (OTUs). Further correlation analyses were performed based on multiple linear regression models with adjustment for covariates and false discovery rate. With the use of MUVR, 35 relevant and minimal optimal OTUs were finally selected. Multiple linear regression analysis showed that the abundance of several OTUs, including OTU334 (belonging to the genus Family XIII AD3011 group), OTU726 (belonging to the species Lachnoclostridium phocaeense), OTU1441 (belonging to the genus Ruminococcus torques group), OTU2553 (belonging to the genus Lachnospiraceae UCG-010), and OTU3375 (belonging to the family Lachnospiraceae), was negatively associated with leukocyte TL (β: –0.187 to –0.142; false discovery rate (FDR)–corrected P value (P_FDR) = 0.009–0.035]. However, neither SCFA subtype nor total SCFA content in feces exhibited significant associations with TL (β: –0.032 to 0.048; P_FDR = 0.915–0.969). The gut microbiota, but not fecal SCFA concentration, was significantly associated with TL in this pediatric population.

Previous research on the association between cesarean section (CS) and childhood obesity has yielded inconsistent findings. This study assessed the secular trend of CS and explored the relationship between CS and the risks of overweight and obesity in Chinese children and adolescents. Data came from a national multicenter school-based study conducted in seven provinces of China in 2013. Covariate data including weight, height and delivery mode were extracted. Poisson regression was applied to determine the risk ratios (RRs) and 95% confidence intervals (CIs) for the risks of overweight and obesity associated with the delivery mode. A total of 18,780 (41.2%) subjects were born by CS between 1997 and 2006. The rate of CS increased from 27.2% in 1997 to 54.1% in 2006. After adjusting for major confounders, the RRs (95% CI) of overweight and obesity among subjects born by CS were 1.21 (1.15 to 1.27) and 1.51 (1.42 to 1.61), respectively. Similar results were observed in different subgroups stratified by sex, age, and region. In summary, the CS rate increased sharply in China between 1997 and 2006. CS was associated with increased risks of overweight and obesity in offspring after accounting for major confounding factors.

Background: Little is known about how the gut microbiota and metabolic profiles are related to cognitive outcomes in young children until now. It was hypothesized that the gut microbiota, the plasma and fecal metabolites significantly correlated with intelligence quotient (IQ) in school-age children in current study. Methods: This cross-sectional study enrolled 452 children aged 6–9 years old. IQ was measured using the Wechsler Intelligence Scale for Children-Fourth Edition. Fecal microbiota, plasma and fecal metabolites were analyzed using 16S rRNA amplicon sequencing and targeted metabolomic technologies, respectively. Results: Restricted maximum likelihood (REML) analyses showed that microbiota composition and fecal metabolites were associated with neither subscale nor full-scale IQ (P: 0.059–0.500). However, plasma metabolites were significantly correlated with the processing speed (P=0.008). In multiple regression analysis after adjusting for confounders and multiple test correction, benzoic acid, azelaic acid, adipic acid, suberic acid and malonic acid selected by the multivariate methods with unbiased variable selection were positively associated with processing speed index (PSI) [P_{false discovery rate (FDR)}: 0.006–0.024], whereas pyruvic acid was negatively associated with the PSI and full-scale IQ (P_FDR: 0.014–0.030). Conclusions: In normal school-age children, certain plasma metabolites concentrations but not the gut microbiota composition nor fecal metabolites are correlated with intelligence.

Phthalates are widely used plasticizers that can leach from consumer products and pose potential health risks, particularly to infants whose developing systems are vulnerable to environmental toxicants. While various exposure pathways have been identified, the contribution of dermal absorption from disposable diapers remains inadequately characterized. This study recruited 66 infants from Guangzhou, a representative city in southern China. Paired disposable diaper and urine samples were collected from each participant. Six phthalates in the diapers and nine metabolites in the urine were quantitatively analyzed. The predominant phthalate detected in the diapers was bis-2-ethylhexyl phthalate (DEHP, with a median concentration of 1670 ng/g, range: 678–5200 ng/g), followed by di-n-butyl phthalate (DnBP, 948 ng/g, range: 189–5980 ng/g), di-iso-butyl phthalate (DiBP, 333 ng/g, range: 16.1–4910 ng/g), and diethyl phthalate (DEP, 252 ng/g, range: 116–3350 ng/g). In urine, metabolites of DEHP (mEHP, mEHHP, and mEOHP) were the most abundant (87.1 ng/mL), followed by mnBP (metabolites of DnBP, 44.6 ng/mL), mEP (metabolites of DEP, 33.7 ng/mL), and miBP (metabolites of DiBP, 13.9 ng/mL). A positive correlation was observed between DnBP levels in diapers and mnBP levels in urine (r = 0.259, p = 0.035). Additionally, several urinary metabolites (miBP, mnBP, and mEP) were positively associated with a biomarker of DNA oxidative damage, 8-hydroxydeoxyguanosine (r = 0.265–0.316, p < 0.01). The estimated daily uptake of DEP, DiBP, DnBP, and DEHP through dermal absorption from diapers accounted for 44.9%, 19.5%, 15.1%, and 7.76% of total exposure to these phthalates, respectively. These findings suggest that dermal absorption from diapers is a significant exposure pathway for infants. Given that both the amount of exposure and the contribution of dermal uptake are higher in younger infants, further attention is warranted to understand the potential effects of transdermal phthalate exposure on infant growth and development.