Vitamin D Status and Associated Factors of Older Adults in the Cross-Sectional 2015-2017 Survey.

Vitamin D is beneficial for maintaining good health; however, there is a lack of nationally representative data reported, particularly in older adults. To better understand the nutritional status of vitamin D and its influencing factors on Chinese older adults, we adopted stratified random sampling to select serum samples originating from the Chronic Disease and Nutritional Survey Biobank of Chinese Residents in 2015-2017. Serum 25-hydroxyvitamin D (25(OH)D) concentrations were determined by enzyme-linked immunoassay. The OR and PR of associated factors for vitamin D deficiency and insufficiency were calculated. In the study, a total of 6273 participants were included. Median serum 25(OH)D concentration was 18.48 (13.27-24.71) ng/mL. The overall rate of vitamin D deficiency and insufficiency was 58.27% (<20 ng/mL), and the VDD rate was 22.17%, which is worse than 5 years ago by nearly 20%. The likelihood of vitamin D deficiency and insufficiency is increased in women, people aged and above 70 years, ethnic minorities, people living in urban areas, midlands, or western areas, warm or medium temperate zones, with middle school and above education level, and people with abdominal obesity and anemia would increase the possibility of vitamin D deficiency and insufficiency with latitude having the greatest impact on vitamin D deficiency and insufficiency. Overall, vitamin D deficiency and insufficiency are very common in Chinese older adults. They should be encouraged to improve their vitamin D nutritional status through enough sunshine exposure and increasing vitamin D intake through diet or supplements.

[Plasma selenium level and its influencing factors in Chinese child-bearing-aged women in 2015].

OBJECTIVE: To assess the plasma selenium(Se) level of child-bearing-aged women and discuss the influence factor for low-Se level. METHODS: Using the muti-stage stratified and population proportional cluster random sampling method, 1881 child-bearing-aged women aged 18 to 44 years were selected from China Adult Chronic Disease and Nutrition Surveillance(2015) Data. The basic information of the subjects was collected by unified electronic questionnaires and equipments were used for field survey, measurement and record. Plasma Se concentration was detected by inductively coupled plasma mass spectrometry. Plasma low-Se level were assessed using lower limit of plasma/serum Se established by the Mayo Clinic Laboratory and our laboratory, respectively. Influence factors of low-Se level were analyzed by the multivariate logistic regression model. RESULTS: The M(P25, P75) plasma Se concentration for Chinese child-bearing-aged women was 89.52(74.21, 105.03)µg/L. Nationality, location, urban-rural type and education level difference had influence on plasma Se level in this population(P<0.05). According to the lower limit of plasma/serum Se concentration established by the Mayo clinical laboratories(<70 µg/L) and our laboratories(<73.81 µg/L), the low-Se rate were 20.47% and 24.51%, respectively. There were significantly differences in low-Se rate among nationality, location, urban-rural type, education level and marital status(P<0.05). The multivariate logistic regression model showed that location and urban-rural type had significant effects on low-Se rate of child-bearing-aged women(P<0.05). CONCLUSION: The plasma low-Se rate of Chinese women of childbearing age is relatively high and higher prevalence low-Se was found in western and central regions and rural areas in China.

Re-exploration of dietary iodine intake in Chinese adult males using a modified iodine balance study.

There is still controversy about optimal dietary iodine intake as the Universal Salt Iodization policy enforcement in China. A modified iodine balance study was thus conducted to explore the suitable iodine intake in Chinese adult males using the iodine overflow hypothesis. In this study, thirty-eight apparently healthy males (19·1 (sd 0·6) years) were recruited and provided with designed diets. After the 14-d iodine depletion, daily iodine intake gradually increased in the 30-d iodine supplementation, consisting of six stages and each of 5 d. All foods and excreta (urine, faeces) were collected to examine daily iodine intake, iodine excretion and the changes of iodine increment in relation to those values at stage 1. The dose-response associations of iodine intake increment with excretion increment were fitted by the mixed effects models, as well as with retention increment. Daily iodine intake and excretion were 16·3 and 54·3 µg/d at stage 1, and iodine intake increment increased from 11·2 µg/d at stage 2 to 118·0 µg/d at stage 6, while excretion increment elevated from 21·5 to 95·0 µg/d. A zero iodine balance was dynamically achieved as 48·0 µg/d of iodine intake. The estimated average requirement and recommended nutrient intake were severally 48·0 and 67·2 µg/d, which could be corresponded to a daily iodine intake of 0·74 and 1·04 µg/kg per d. The results of our study indicate that roughly half of current iodine intakes recommendation could be enough in Chinese adult males, which would be beneficial for the revision of dietary reference intakes.

Re-exploring the requirement of dietary iodine intake in Chinese female adults based on 'iodine overflow theory'.

PURPOSE: We re-explored the basal iodine requirement based on healthy Chinese female and a new iodine overflow theory was proposed for iodine balance study. METHODS: Thirty-six Chinese healthy female adults (age 20.7 ± 1.1) were recruited for this study, which included 40 days low iodine depletion period and six stages of 30 days supplementation period. Uniform diets with low iodine were provided and the content of iodine in the diet was regulated by dairy products. The total iodine intake from food and the total iodine excretion through 24-h urine and staged feces were completely gathered and monitored. The incremental (Δ) intake and excretion over the range were calculated. RESULTS: The iodine intake and excretion were 13.6 µg/day and 48.6 µg/day at the first stage, respectively. The incremental iodine intakes and excretions were 21.1 µg/day to 120.3 µg/day and 25.8 µg/day to 105.4 µg/day for the supplementation stages, respectively. According to the 'iodine overflow theory', the zero iodine balance (Δ iodine intake = Δ iodine excretion) derived from a mixed effect model indicated a mean iodine intake of 52.2 µg/d (1.0 µg/d kg). The RNI for iodine to healthy Chinese female adult was 73.1 µg/d (1.4 µg/d kg). CONCLUSION: A daily iodine intake of 52.2 µg/d may meet the basal iodine requirement for healthy Chinese female adults, and Chinese female may need more than 20% iodine intake than male based on the 'iodine overflow theory'. The trial was registered at the Chinese Clinical Trial Registry in May 2018 (No: ChiCTR1800016184).

Higher selenium was associated with higher risk of diabetes: Consistent evidence from longitudinal and cross-sectional studies based on nail and serum selenium measures.

Although the association between selenium (Se) and diabetes has been well-discussed in recent years, few studies have focused on the effects of long-term natural Se exposure and rarely concerned the effects of different Se biomarkers. To address this question, we carried out a 7-year longitudinal study on older adults aged over 65 and another cross-sectional study on middle-aged and older adults aged 40 and above from Chinese soil Se-deplete and Se-optimum areas. Cox proportional hazard models were used to evaluate the associations between nail Se levels and incidence risk of diabetes. Unconditional logistic regression models and analysis of variance models were used to examine the associations between serum Se levels and the prevalence risk of diabetes. The nail and serum Se levels were 0.47 ± 0.20 µg/g and 111.09 ± 55.01 µg/L for the two study populations, respectively. For both of the independent studies, higher Se levels were observed to be associated with a higher risk of diabetes and prediabetes. Compared with the Second nail Se quartile (Q2), the adjusted hazard ratios (HRs) and 95 % confidence intervals (95 % CIs) of diabetes for Q1, Q3 and Q4 were 1.24(0.70, 2.21), 1.53(0.98, 2.39) and 1.31(0.76, 2.26), respectively, and the adjusted HRs (95 % CIs) of prediabetes were 1.47(0.77, 2.81), 1.38(0.83, 2.30), and 1.97(1.13, 3.44), respectively. Compared with the first serum Se quintile (Q1), the adjusted odds ratios (ORs) and 95 % CIs of diabetes for higher quintiles were 1.12(0.75, 1.66), 1.05(0.71, 1.57), 1.09(0.73, 1.62) and 1.51(1.02, 2.19), and the adjusted ORs (95 % CIs) of prediabetes were 1.27(0.77, 2.09), 1.70(1.05, 2.74), 1.94(1.21, 3.11) and 1.67(1.03, 2.71). Our findings consistently suggest that higher Se status is associated with a higher risk of diabetes in adults.

Reference Ranges of Selenium in Plasma and Whole Blood for Child-Bearing-Aged Women in China.

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 P2.5-P97.5 percentiles (geometric mean) was 73.81-140.75 (100.94) µg/L and P2.5-P97.5 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 P2.5 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.

Vitamin D Nutritional Status of Chinese Pregnant Women, Comparing the Chinese National Nutrition Surveillance (CNHS) 2015-2017 with CNHS 2010-2012.

Optimal vitamin D (vitD) status is beneficial for both pregnant women and their newborns. The aim of this study was to evaluate the vitamin D status of Chinese pregnant women in the latest China Nutrition and Health Surveillance (CNHS) 2015-2017, analyze the risk factors of vitamin D deficiency (VDD), and compare them with those in CNHS 2010-2012. Serum 25 hydroxyvitamin D (25(OH)D) was measured by ELISA method. City type, district, latitude, location, age, vitamin D supplements intake, education, marital status, annual family income, etc., were recorded. The median 25(OH)D concentration was 13.02 (10.17-17.01) ng/mL in 2015-2017, and 15.48 (11.89-20.09) ng/mL in 2010-2012. The vitamin D sufficient rate was only 12.57% in 2015-2017, comparing to 25.17% in 2010-2012. The risk factors of vitamin D inadequacy (25(OH)D < 20 ng/mL) in 2015-2017 were not exactly consistent with that in 2010-2012. The risk factors included season of spring (p < 0.0001) and winter (p < 0.001), subtropical (p < 0.001), median (p < 0.0001) and warm temperate zones (p < 0.0001), the western (p = 0.027) and the central areas (p = 0.041), while vitD supplements intake (p = 0.021) was a protective factor in pregnant women. In conclusion, vitD inadequacy is very common among Chinese pregnant women. We encourage pregnant women to take more effective sunlight and proper vitD supplements, especially for those from the subtropical, warm and medium temperate zones, the western and the central, and in the seasons of spring and winter.

Physiologic requirement for iron in pregnant women, assessed using the stable isotope tracer technique.

BACKGROUND: Knowledge of the physiologic requirement for iron, the core index for the formulation of a dietary reference intake (DRI), is of great importance for the health of a pregnant woman and her fetus, and can help a mother accurately plan her iron supplementation. However, direct measurements of the physiologic requirement for iron during pregnancy are still lacking. METHOD: Eleven women of reproductive age from Hebei Province, China, who planned to become pregnant in the near future, were enrolled between January and March 2015 and included in the final analysis. Subjects participated in a 2-week metabolic trial in which they consumed 50 mg of the stable isotope 58Fe, and were then followed for ~ 2 years. The abundance of 58Fe and the total iron concentration in the circulation were measured using Multi-collector Inductively-Coupled Plasma Mass Spectrometry and Atomic Absorption Spectroscopy, respectively. The physiologic requirement for iron during pregnancy was then calculated by the formula derived from our previously published work. RESULTS: The mean physiologic requirement for iron in the 11 subjects, across their entire pregnancies, was 3.05 mg.d- 1 in total and 44.0 µg.kg- 1.d- 1 after adjustment for body mass. The physiologic requirements for iron in the first, second, and third trimesters were 2.04 mg.d- 1, 3.26 mg.d- 1, and 4.13 mg.d- 1, respectively. When adjusted for body mass, the physiologic requirements for iron in different trimesters were 32.3 µg.kg- 1.d- 1, 46.9 µg.kg- 1.d- 1, and 55.7 µg.kg- 1.d- 1, respectively. CONCLUSION: We preliminarily explored the physiologic requirement for iron in pregnant women. The data demonstrated that pregnant women needed about twice iron than non-pregnant women. This research may be helpful for the design of future studies and the modification of iron DRIs. TRIAL REGISTRATION: ChiCTR, ChiCTR-OCH-14004302. Registered 14 February 2014, http://www.chictr.org.cn/showproj.aspx?proj=5267.

Vitamin D deficiency prevalence and risk factors among pregnant Chinese women.

OBJECTIVE: To evaluate vitamin D deficiency prevalence and risk factors among pregnant Chinese women. DESIGN: A descriptive cross-sectional analysis. SETTING: China National Nutrition and Health Survey (CNNHS) 2010-2013. SUBJECTS: A total of 1985 healthy pregnant women participated. Possible predictors of vitamin D deficiency were evaluated via multiple logistic regression analyses. RESULTS: The median serum 25-hydroxyvitamin D level was 15·5 (interquartile range 11·9-20·0, range 3·0-51·5) ng/ml, with 74·9 (95 % CI 73·0, 76·7) % of participants being vitamin D deficient (25-hydroxyvitamin D <20 ng/ml). According to the multivariate logistic regression analyses, vitamin D deficiency was positively correlated with Hui ethnicity (P=0·016), lack of vitamin D supplement use (P=0·021) and low ambient UVB level (P<0·001). In the autumn months, vitamin D deficiency was related to Hui ethnicity (P=0·012) and low ambient UVB level (P<0·001). In the winter months, vitamin D deficiency was correlated with younger age (P=0·050), later gestational age (P=0·035), higher pre-pregnancy BMI (P=0·019), low ambient UVB level (P<0·001) and lack of vitamin D supplement use (P=0·007). CONCLUSIONS: Vitamin D deficiency is prevalent among pregnant Chinese women. Residing in areas with low ambient UVB levels increases the risk of vitamin D deficiency, especially for women experiencing advanced stages of gestation, for younger pregnant women and for women of Hui ethnicity; therefore, vitamin D supplementation and sensible sun exposure should be encouraged, especially in the winter months. Further studies must determine optimal vitamin D intake and sun exposure levels for maintaining sufficient vitamin D levels in pregnant Chinese women.

[Study on serum selenium level of people in service sectors in Taigu County, Shanxi Province].

OBJECTIVE: To detect serum selenium level of people in non-selenium-deficiency region. METHODS: A total of 793 subjects were recruited by random sampling from people engaged in service sectors in Taign county, Shanxi province. Information about gender, age, occupation and educational level were collected and the content of serum selenium was measured by fluorospectrophotometry. All data were statistically analyzed with SPSS software version 13.0. RESULTS: The age distribution for these samples ranged from 20 to 67 years old. Their average serum selenium level and standard deviation (SD) were (0.0913 +/- 0.0186) mcirog/ml, (0.0947 +/- 0.0184) microg/ml and (0.0887 +/- 0.0184) microg/ml for total, male and female, respectively, and the level of male was significantly higher than that of female. There were no significant differences of serum selenium in each group of different ages, occupation, and educational level. Serum selenium in male were significantly higher than in female in both 20-29 years old group and 30-39 years old group, but there were no significant differences in groups older than 40. In 30-39 years old group, male had the highest serum selenium, but female occurred just the opposite. There was a decrease of serum selenium in male older than 40, but a great increase in female. CONCLUSION: The serum selenium level of adults in this area was adequate, but compared with progressed areas in the world, it could be categorized as low-middle level, serum selenium in male of 20-40 years old was significantly higher than in female, but the differences turn to be narrow in people older than 40 years old.