Iodine deficiency causes a broad spectrum of disorders across all ages. Mandatory salt iodization in Taiwan successfully reduced the goiter rate from 21.6% to 4.3% in schoolchildren surveyed in 1971. The program continued until 2003 when salt iodization was changed from mandatory to voluntary. The purpose of this study was to investigate the iodine status of Taiwanese individuals after the change in the iodine policy. Urinary iodine (UI) was measured in samples from adults in the Nutrition and Health Survey in Taiwan 2005-2008. The median UI level was 100 μg/L, and the percentage of populations with UI levels below 100 μg/L and 50 μg/L was 50.1% and 15.1%, respectively, indicating that the iodine status was borderline adequate. Men had a higher UI level than women (102 μg/L vs. 98 μg/L, p = 0.003), and older individuals (age > 60 years) had a lower UI level than younger people, particularly in women. The iodine status of the population < 50 years was sufficient, but it was insufficient in older groups. Mild iodine insufficiency was noted in all areas of Taiwan except the Southern area and Penghu islands, with the lowest UI level of 79 μg/L in the Mountain area. Although the UI level of women of childbearing age (19-44 years) was 103 μg/L, there may be a risk of iodine deficiency during pregnancy. The iodine nutrition of the Taiwanese population in 2005-2008 was borderline adequate, with insufficiency in some subgroups. Further monitoring of the iodine status is necessary.

Hepcidin is a regulator of iron metabolism. Diet affects the body’s iron status, but how it influences hepcidin concentrations and the risk of gestational iron-deficiency anemia (IDA) remains unclear. We investigated relationships of food and nutrient intake with serum hepcidin levels in relation to the iron status at a population scale. A retrospective cross-sectional study was conducted based on data obtained from the Nationwide Nutrition and Health Survey in pregnant women, Taiwan (2017~2020). In total, 1430 pregnant women aged 20~45 years with a singleton pregnancy were included. Data from blood biochemistry, 24-h dietary recall, and a food frequency questionnaire were collected during a prenatal checkup. Adjusted multivariate linear and logistic regression analyses were employed to measure the beta coefficient (ß) and 95% confidence interval (CI) of serum hepcidin and the odds ratio (OR) of IDA. In IDA women, serum hepcidin levels were positively correlated with the intake frequency of Chinese dim sum and related foods (β = 0.037 (95% CI = 0.015~0.058), p = 0.001) and dark leafy vegetables (β = 0.013 (0.001~0.025), p = 0.040), but they were negatively correlated with noodles and related products (β = −0.022 (−0.043~−0.001), p = 0.038). An adjusted multivariate logistic regression analysis showed that dietary protein [OR: 0.990 (0.981~1.000), p = 0.041], total fiber [OR: 0.975 (0.953~0.998), p = 0.031], and rice/rice porridge [OR: 1.007 (1.00~1.014), p = 0.041] predicted gestational IDA. Total carbohydrates [OR: 1.003 (1.000~1.006), p = 0.036], proteins [OR: 0.992 (0.985~0.999), p = 0.028], gourds/shoots/root vegetables [OR: 1.007 (0.092~1.010), p = 0.005], and to a lesser extent, savory and sweet glutinous rice products [OR: 0.069 (0.937~1.002), p = 0.067] and dark leafy vegetables [OR: 1.005 (0.999~1.011), p = 0.088] predicted IDA. The risk of IDA due to vegetable consumption decreased with an increasing vitamin C intake (p for trend = 0.024). Carbohydrates and vegetables may affect the gestational iron status through influencing hepcidin levels. Vitamin C may lower the risk of gestational IDA due to high vegetable consumption.

Urinary iodine concentration (UIC) measured by Sandell-Kolthoff spectrophotometric method has been used in the Nutrition and Health Surveys in Taiwan but this method is time consuming and produces toxic waste from arsenic trioxide. The aim of this study was to develop and validate an inductively coupled plasma mass spectrometry (ICP-MS) system to determine UIC in Taiwan. Samples and iodine calibrators were diluted 100-fold into an aqueous solution containing Triton X-100, 0.5% ammonia solution, and tellurium (¹²⁸Te) as an internal standard. Digestion prior to analysis was not necessary. Precision, accuracy, serial dilution, and recovery tests were performed. A total of 1243 urine samples covering a wide range of iodine concentrations were measured by both Sandell-Kolthoff method and ICP-MS. Passing-Bablok regression and Bland-Altman plots were used to compare values across methods. The limit for detection and quantification by ICP-MS was 0.95 μg/L and 2.85 μg/L, respectively. The intra-assay and inter-assay coefficients were <10%, with a recovery range of 95%-105%. The results obtained by ICP-MS and the Sandell-Kolthoff method were highly correlated (Pearson's correlation: r = 0.996, 95% confidence interval [CI]: 0.9950-0.9961, p < 0.001). For UIC between 20 and 1000 μg/L, the y-intercept for the Passing-Bablok regression was -1.9 (95% CI: -2.5599 to -1.3500) and the slope was 1.01 (95% CI: 1.0000-1.0206). This validated ICP-MS system can be used for measuring UIC.

Globally, anemia affects 56 million pregnant women, especially women with a low household income. Functional erythropoiesis requires a constant supply of micronutrients, and the demands significantly increase during fetal development. This study aims to identify dietary patterns for preventing gestational erythropoiesis-associated micronutrient deficiencies (e.g., iron, folic acid, and vitamin B₁₂). A Nationwide Nutrition and Health Survey in Pregnant Women, Taiwan (NAHSIT-PW), was conducted between 2017 and 2019. Data on baseline information, diet, anthropometrics, and blood biochemistry were collected during a prenatal visit. Dietary patterns were identified using a reduced rank regression (RRR). Erythropoiesis-related micronutrient deficiencies were defined as single, double, and triple micronutrient deficiencies of an iron deficiency, folate depletion, and a vitamin B₁₂ deficiency. In total, 1437 singleton pregnancies aged ≥20–48 years were included in the analysis. Prevalences of normal nutrition, and single, double, and triple erythropoiesis-related micronutrient deficiencies were 35.7%, 38.2%, 18.6%, and 7.5%, respectively. Anemic pregnant women with a low household income had the highest prevalence rates of double (32.5%) and triple (15.8%) erythropoiesis-related micronutrient deficiencies. Dietary pattern scores were positively correlated with nuts and seeds, fresh fruits, total vegetables, breakfast cereals/oats and related products, soybean products, and dairy products but negatively correlated with processed meat products and liver, organs, and blood products. After adjusting for covariates, the dietary pattern had 29% (odds ratio (OR): 0.71; 95% confidence interval (CI): 0.055–0.091, p = 0.006)) and 43% (OR: 0.57; 95% CI: 0.41–0.80, p = 0.001)) reduced odds of having double and triple erythropoiesis-related micronutrient deficiencies for those pregnant women with a low household income. For those women with anemia, dietary patterns had 54% (OR: 046, 95% CI: 0.27–0.78) and 67% (OR: 0.33; 95% CI: 0.170.64) reduced odds of double and triple erythropoiesis-related micronutrient deficiencies. In conclusion, increased consumption of breakfast cereals and oats, nuts, and seeds, fresh fruits and vegetables, soybean products, and dairy products may protect women against erythropoiesis-related micronutrient deficiencies during pregnancy.

Vitamin D’s function in the development of gestational diabetes mellitus (GDM) is not consistent in the literature. We examined the association between maternal plasma 25(OH)D concentration and GDM risk. A national cross-sectional study (1497 pregnant women) was conducted between 2017 and 2019 across Taiwan. Blood samples were drawn at recruitment to assess 25(OH)D concentrations, including vitamin D deficiency (VDD) (<20 ng/mL), insufficiency (<32 ng/mL), and sufficiency (≥32 ng/mL). GDM was detected from 24 to 28 weeks of gestation with the results extracted from the antenatal visit records. The prevalence of GDM was 2.9%. Logistic model analysis showed that 25(OH)D concentrations were not significantly associated with the risk of GDM (adjusted odds ratio (AOR) = 0.97, p = 0.144). However, subjects with VDD had a significantly greater risk of GDM (AOR = 2.26, p = 0.041), but not in those with vitamin D insufficiency (AOR = 1.20, p = 0.655). Furthermore, cubic piecewise spline regression was used to explore the relationship between five-unit intervals of 25(OH)D and the predicted probability of GDM. As the proportion of GDM increased for low 25(OH)D concentrations, it decreased at moderate concentrations and increased again at higher concentrations. These findings revealed a nonlinear relationship between 25(OH)D and GDM risk. VDD would be risky for GDM occurrence.