Iron deficiency (ID) and iron deficiency anemia (IDA) typically occur in developing countries. Notably, ID and IDA can affect an infant’s emotion, cognition, and development. Breast milk is considered the best food for infants. However, recent studies have indicated that breastfeeding for more than six months increases the risk of ID. This study investigated the prevalence of ID and IDA, as well as the association between feeding type and iron nutritional status in northern Taiwan. A cross-sectional study was conducted on infants who returned to the well-baby clinic for routine examination from October 2012 to January 2014. Overall, 509 infants aged 1–12 months completed the iron nutritional status analysis, anthropometric measurement, and dietary intake assessment, including milk and complementary foods. The results revealed that 49 (10%) and 21 (4%) infants in their first year of life had ID and IDA, respectively, based on the World Health Organization criteria. Breastfed infants had a higher prevalence rate of ID and IDA than mixed-fed and formula-fed infants (p < 0.001). Regarding biomarkers of iron status, plasma hemoglobin (Hb), ferritin, and transferrin saturation (%) levels were significantly lower in ID and IDA groups. The prevalence of ID and IDA were 3.7% and 2.7%, respectively, in infants under six months of age, but increased to 20.4% and 6.6%, respectively, in infants above six months of age. The healthy group had a higher total iron intake than ID and IDA groups, mainly derived from infant formula. The total dietary iron intake was positively correlated with infants’ Hb levels. Compared with formula-fed infants, the logistic regression revealed that the odds ratio for ID was 2.157 (95% confidence interval [CI]: 1.369–3.399) and that for IDA was 4.196 (95% CI: 1.780–9.887) among breastfed infants (p < 0.001) after adjusted for all confounding factors (including gestational week, birthweight, sex, body weight percentile, body length percentile, age of infants, mothers’ BMI, gestational weight gain, education level, and hemoglobin level before delivery). In conclusion, our results determined that breastfeeding was associated with an increased the prevalence of ID and/or IDA, especially in infants above six months. This suggests that mothers who prolonged breastfeed after six months could provide high-quality iron-rich foods to reduce the prevalence of ID and IDA.

Vitamin D deficiency (VDD) and insufficiency (VDI) are common among exclusively breastfeeding infants. However, epidemiological evidence for the prevalence of VDD in infants during their first year of life in Taiwan has never been found. This trial determined the prevalence of VDD and VDI and the association between dietary vitamin D and vitamin D nutritional status in Northern Taiwan. A cross-sectional study was conducted on infants who returned to well-baby examinations from October 2012 to January 2014 in three hospitals: Shin Kong Wu Ho-Su Memorial Hospital, Taipei Medical University Hospital, and Shuang Ho Hospital. The specific vitamin D cut-off concentrations for VDD, VDI, and VDS are 25(OH)D₃ levels ≤20, 21–29, and ≥30 (ng/mL). Overall, 481 infants’ parents completed a questionnaire comprising questions related to vitamin D nutritional status, including weekly time outdoors, breastfeeding status, anthropometric measurement, and assessment of dietary intake, including milk and complementary food. The results revealed that 197 (41%) and 212 (44%) of infants in their first year of life had VDI and VDD, respectively, by the Endocrine Society guidelines. Breastfed infants had a higher prevalence of VDI (86.1%) than did mixed-fed (51.9%) and formula-fed (38.5%) infants (p < 0.001). The prevalence of VDD was 55.4% in infants aged under six months but increased to 61.6% in infants aged over six months. Infants in the VDI and VDD groups had the same anthropometrics as those in the vitamin D sufficiency (VDS) group. Our results revealed that 25(OH)D₃ had a negative correlation with the intact parathyroid hormone (iPTH) when the serum 25(OH)D₃ level ≤20 ng/mL (r = −0.21, p = 0.001). The VDS group had a higher total vitamin D intake than did the VDI and VDD groups, which was mainly obtained from infant formula. Our data revealed that dietary vitamin D intake and birth season were major indicators in predicting VDD. Lower dietary vitamin D intake and born in winter and spring significantly increased the odds ratio (OR) for VDI by 1.15 (95% CI 1.09–1.20) and 2.02 (95% CI 1.10–3.70), respectively, and that for VDD by 1.23 (95% CI 1.16–1.31) and 2.37 (95% CI 1.35–4.17) without covariates adjustment, respectively. Furthermore, ORs for VDI and VDD significantly differed after adjustment for covariates. In conclusion, the prevalence of VDI and VDD were high in infants during the first year of life. Breastfeeding infants had difficulty in obtaining sufficient vitamin D from diet. In cases where the amount of sun exposure that is safe and sufficient to improve vitamin D status is unclear, breastfed infants aged below one year old are recommended to be supplemented with vitamin D.

Background/Objectives: Ultra-processed food (UPF) consumption has increased worldwide, but evidence regarding its dietary and health associations among preschool children in East Asia remains limited. This study examined the associations of UPF intake with nutrient intake, anthropometric status, dental caries, and constipation-related symptoms among preschool children in Taiwan. Methods: This cross-sectional study included 822 children aged 2–6 years recruited from 82 kindergartens in Taipei, Taiwan. Habitual dietary intake was assessed using a 107-item semi-quantitative food frequency questionnaire, and foods were classified using an adapted NOVA-based framework. Participants were categorized into quartiles according to the percentage of total energy intake derived from UPFs. Anthropometric data were available for 777 children and dental examination data for 746 children. Six constipation-related symptoms derived from the Rome IV criteria were assessed based on parental reports of symptoms during the previous 3 months. Differences across UPF quartiles were examined using chi-square tests and one-way analysis of variance. Multivariable regression models were used to evaluate associations of UPF intake and specific food groups with dental caries and constipation-related symptoms. Results: UPFs contributed a mean of 15.12% of total energy intake. Higher UPF intake was associated with lower intakes of dietary fiber, protein, potassium, calcium, magnesium, zinc, phosphorus, retinol equivalents, vitamin B1, vitamin B2, vitamin B6, vitamin B12, and vitamin C, and with higher intakes of total fat, saturated fatty acids, and sodium. No significant differences in height percentile, weight percentile, or anthropometric status were observed across UPF quartiles. Among the 746 children with dental examination data, dental caries experience (defined as the presence of at least one decayed or filled tooth) increased from 12.8% in Q1 to 31.2% in Q4 (p < 0.001). After adjustment for age group, sex, total energy intake, and frequency of home cooking, children in Q4 had a higher prevalence of dental caries than those in Q1 (aPR = 2.270, 95% CI: 1.480–3.480; p < 0.001; p for trend < 0.001). Higher UPF intake was also associated with greater constipation-related symptom scores. Compared with Q1, constipation-related symptom scores were 0.900 points higher in Q4 (β = 0.900, 95% CI: 0.330–1.470; p = 0.002). After additional adjustment for dietary fiber intake, this association was attenuated but remained significant (β = 0.680, 95% CI: 0.110–1.260; p = 0.019). In mutually adjusted food-group analyses, higher fruit intake was associated with lower constipation-related symptom scores (β = −0.219, 95% CI: −0.353 to −0.086; p = 0.001), whereas higher biscuit/snack intake was associated with higher constipation-related symptom scores (β = 1.193, 95% CI: 0.441–1.946; p = 0.002). Higher vegetable intake was associated with a lower prevalence of dental caries (aPR = 0.810, 95% CI: 0.660–0.990; p = 0.038). Conclusions: Higher UPF intake among Taiwanese preschool children was associated with an unfavorable nutrient profile, higher dental caries prevalence, and more frequent constipation-related symptoms, but not with differences in anthropometric status. The attenuation of the UPF–constipation association after adjustment for dietary fiber suggests that lower fiber intake may partly contribute to this association. These findings support dietary guidance that emphasizes reducing UPF consumption and promoting minimally processed, nutrient-dense foods, particularly fruits, vegetables, and other fiber-rich foods, during early childhood.

Background/Objectives: Evidence on ultra-processed food (UPF) consumption and health among East Asian preschoolers is limited. We examined associations with nutrient intake, anthropometry, dental caries, and bowel symptoms in Taiwan. Methods: This cross-sectional study included 822 children aged 2–6 years. A caregiver-reported 107-item food frequency questionnaire estimated UPF energy contribution using an adapted NOVA framework; anthropometric and dental data were available for 777 and 746 children, respectively. Results: UPFs supplied 15.12% of energy. Higher UPF intake was associated with lower fiber, protein, and several micronutrient intakes and higher saturated fat and sodium intakes, without significant anthropometric differences. Caries prevalence was 12.8% in Q1 and 31.2% in Q4 (adjusted prevalence ratio [aPR] = 2.27, 95% confidence interval [CI]: 1.48–3.48). Relative to Q1, Q3 showed higher prevalences of infrequent bowel movements (aPR = 1.48, 95% CI: 1.09–2.00) and hard stools (aPR = 1.23, 95% CI: 1.01–1.49); Q4 associations were not statistically significant. Exploratory food-group analyses associated fruit intake with lower reported frequency of infrequent bowel movements and biscuit/snack intake with higher hard stool frequency. Conclusions: Higher UPF intake was associated with unfavorable nutrient profiles, dental caries, and selected caregiver-reported bowel symptoms, but not anthropometric status. Further longitudinal studies are warranted to clarify the temporal relationships between UPF consumption and these health outcomes during early childhood.