Magnesium (Mg) is an essential nutrient that participates in various enzymatic reactions and regulates important biological functions. The distribution and reference ranges in China have not been reported in populations more than 45 years old. This study aimed to assess the magnesium status and determine the reference values of plasma Mg, Ca, and Ca/Mg ratios for China’s population more than 45 years old. A total of 2101 people were randomly selected from the China Nutrition and Health surveillance (CNHS) (2015–2017), considering the regional types and monitoring points. Then, 337 healthy individuals were further selected by a series of strict inclusion criteria to explore the reference range. The plasma magnesium and calcium were tested by inductively coupled plasma mass spectrometry (ICP-MS). The suggested reference values for plasma Mg, Ca, and Ca/Mg ratios were 0.75–1.14 mmol/L, 2.17–3.64 mmol/L, and 2.36–3.66, respectively. Taking 0.75 mmol/L as the lower cut-off limit, the prevalence of Mg deficiency was 6.66%, and the average level of plasma magnesium was 0.88 mmol/L for populations older than 45 years in China. In conclusion, this study provides the magnesium status and reference ranges for plasma Mg, Ca, and Ca/Mg ratio for Chinese people over 45 years old. The results of the recommended reference ranges in this study were very similar to our published results in women of reproductive age. Thus, the reference range of plasma magnesium in different populations in China was further improved.

Selenium (Se) is a “dual-surface” element. Both Se-deficiency and Se-overload have bad effects on humans. The amount of Se in the blood is a good indicator of Se intake, and there are considerable differences in the reference ranges among different regions and populations. The purpose of this study was to establish the age-specific reference interval of blood Se in healthy child-bearing-aged women in China. A total of 187 healthy women aged 18–45 years old were enrolled with strict inclusion criteria from the China Adult Chronic Disease and Nutrition Surveillance (2015 CACDNS) database to establish the reference interval of Se. Plasma and whole-blood Se were detected by inductively coupled plasma mass spectrometry (ICP-MS). The reference range (RR) estimated as P_2.5–P_97.5 percentiles (geometric mean) was 73.81–140.75 (100.94) μg/L and P_2.5–P_97.5 percentiles (median) 81.06–164.75 (121.05) μg/L for plasma and whole-blood Se, respectively. The proposed RR of plasma Se in this study was used to evaluate the Se nutritional status of a representative sample of 1950 women of child-bearing age who were randomly selected from 2015 CACDNS. The proportion of Se level lower than P_2.5 cut-off value was 24.05%, and there were 5.08% child-bearing-aged women with plasma Se higher than the upper limit of RR. Women in the western and rural areas tend to have lower Se levels.

Background: Magnesium (Mg) is an essential element and participates in many metabolic pathways. Many studies have found a certain negative correlation between magnesium and blood glucose parameters, but the dose–response relationship between them is still a relatively narrow research field. We aim to explore the dose–response relationship between plasma and dietary Mg and type 2 diabetes (T2DM) among childbearing women in a nationally representative sample. And we will also initially explore the threshold of dietary and plasma magnesium in the prevention of T2DM and their consistency. Methods: A total of 2912 18–44 year-old childbearing women were recruited from the China Adult Chronic Disease and Nutrition Surveillance (2015). Multivariate logistic regression was used to explore the dose–response relationship between plasma and dietary Mg and glucose parameters. The threshold effect between Mg and T2DM was explored by a restricted cubic spline regression. Results: It was found that when plasma Mg was increased by 0.041 mmol/L, the risk of T2DM, impaired fasting glucose (IFG), and HbA1c-hyperglycemia was reduced by 18%, 19%, and 18%, respectively. The possible threshold value for plasma Mg to prevent the risk of T2DM was 0.87 mmol/L. Through the quality control of the sample dietary survey data, 2469 cases were finally included for dietary analysis. And the possible threshold value for dietary Mg to prevent the risk of T2DM was 408 mg/d. Taking the recommended dietary Mg intake of 330 mg/d as the reference group, when the Mg intake reached 408 mg/d, the risk of T2DM was significantly reduced. And the average plasma Mg level of the people whose dietary intake reached 408 mg/d was 0.87 mmol/L. Conclusions: These results indicate that dietary Mg and plasma Mg have good consistency on the threshold effect of glucose parameters in women of childbearing age.

Although several studies have shown the relationship between magnesium and diabetes, there are few studies regarding the association between magnesium status and prediabetes. This study aimed to examine the association between dietary magnesium intake and the risk of prediabetes in childbearing Chinese women (18–44 years). A total of 1981 participants without diabetes were randomly selected from China Nutrition and Health Surveillance (CNHS) in 2015 by considering the regional types and monitoring points, including 1420 normal fasting glucose (NFG) people and 561 prediabetes cases. The Food Frequency Questionnaire (FFQ) and inductively coupled plasma mass spectrometry (ICP-MS) measured dietary and plasma magnesium. The results of this study showed that dietary magnesium intake was inversely associated with fasting plasma glucose. For every 100 mg of magnesium intake, there was a 0.052 mmol/L (95% CI 0.019, 0.085) reduction in fasting plasma glucose (p = 0.002). Compared with the lowest intake quartile (<350.10 mg/day), the third and fourth quartiles (≥405.41 mg/day) reduced the odds risk of prediabetes (OR = 0.63, 95% CI 0.46, 0.88, p = 0.020) by approximately 37%. The dose-response curves for the association between magnesium intake and prediabetes followed an L shape. The odds ratio of prediabetes decreased significantly with increasing dietary Mg intake at less than 410 mg/day, and then the curve leveled off or slightly increased. This study found a negative association between dietary magnesium intake and prediabetes in childbearing Chinese women. The risk of prediabetes was reduced with increasing dietary magnesium intake, and the threshold value was 410 mg/day. This suggests that childbearing women also need to pay attention to their magnesium status.

Objectives: Although some studies have assessed Selenium nutritional status in different populations, determining the plasma Selenium levels and describing the distribution of dietary Selenium intake in Chinese female adults by using nationally representative data was lacking. The objective was to describe the plasma/dietary Selenium status in Chinese female adults and analyze the possible influencing factors related to dietary Selenium levels. Method: A total of 3016 female adults from China Nutrition and Health Surveillance in 2015 (CNHS 2015) were included. The plasma Selenium concentration was detected by inductively coupled plasma mass spectrometry (ICP-MS). Dietary Selenium intake (Y, μg/d) was calculated from plasma Selenium concentrations (X, μg/L) using the formula lg(Y) = 1.624 lg(X) + 3.389. A multivariate logistic regression model was used to explore the risk factors of low dietary Selenium intake. Results: The median levels of plasma Selenium and dietary Selenium in Chinese adult females were 89.97 μg/L and 49.03 μg/d, respectively. The normal reference range of plasma Selenium in this population was 72.04~141.11 μg/L. There was a higher risk of low dietary Selenium intake in central, western, and northern regions. In general, the plasma Selenium levels in Chinese adult females were lower than those in countries such as the United States and Japan but higher than those in some European countries. Conclusions: The plasma Selenium levels varied greatly in different regions of China, with typical regional characteristics. Therefore, it was necessary to monitor Selenium nutrition monitoring in specific regions.