Low selenium intake is associated with postpartum weight retention in Chinese women and impaired physical development of their offspring.

The aim of this study was to investigate the association between daily Se intake and postpartum weight retention (PPWR) among Chinese lactating women, and the impact of their Se nutritional status on infants' physical development. Se contents in breast milk and plasma collected from 264 lactating Chinese women at the 42nd day postpartum were analysed with inductively coupled plasma MS. Daily Se intake was calculated based on plasma Se concentration. The dietary data of 24-h records on three consecutive days were collected. Infant growth status was evaluated with WHO standards by Z-scores. Linear regression analyses and multinomial logistic regression were conducted to examine the impact of Se disequilibrium (including other factors) on PPWR and growth of infants, respectively. The results indicated that: (1) the daily Se intake of the subjects was negatively associated with their PPWR (B = -0·002, 95 % CI - 0·003, 0·000, P = 0·039); (2) both insufficient Se daily intake (B = -0·001, OR 0·999, 95 % CI 0·998, 1·000, P = 0·014) and low level of Se in milk (B = -0·025, OR 0·975, 95 % CI 0·951, 0·999, P = 0·021) had potential associations with their infants' wasting, and low level of Se in milk (B = -0·159, OR 0·853, 95 % CI 0·743, 0·980, P = 0·024) had a significant association with their infants' overweight. In conclusion, the insufficient Se nutritional status of lactating Chinese women was first found as one possible influencing factor of their PPWR as well as low physical development of their offspring.

Dietary Serine and Sulfate-Containing Amino Acids Related to the Nutritional Status of Selenium in Lactating Chinese Women.

Previous studies suggested that serine can promote the synthesis of selenoproteins and the interaction, transformation, and replacement of serine, cysteine, and selenocysteine have been observed in the human body. This study was designed to clarify whether the dietary intakes of serine and sulfate-containing amino acids (SAAs) could directly affect the selenium (Se) nutritional status or the level of milk Se in lactating women. Breast milk and plasma samples were collected from a total of 264 lactating Chinese women when they revisited their local hospital at the 42nd day postpartum to detect the concentration of Se with ICP-MS and the content of selenoprotein P (SEPP1) and the activity of glutathione peroxidase 3 (GPX3) in the plasma by ELISA. The daily Se intake by each subject was calculated based on her own plasma Se concentration. The 24-h dietary record data for 3 consecutive days were collected to calculate their dietary intakes of protein together with each amino acid daily based on the China Food Composition Tables (CFCT). Ordinal polytomous logistic regression was applied to examine the determinants of BMI values for lactating women. For all subjects, the concentration of plasma SEPP1 and milk Se of participants with insufficient Se intake were significantly associated with the dietary intake of serine and 2 SAAs (methionine and cystine), respectively (P < 0.05). No significant correlation was found between each amino acid related to the synthesis of endogenous serine and every biomarker of the Se nutrition status in subjects with an insufficient dietary protein intake (P > 0.05). The ordinal logistic regression analysis showed that dietary protein intake (ordinal OR 1.012, 95% CI = 0.004-0.020, P = 0.002) and plasma SEPP1 (ordinal OR 0.988, 95% CI = - 0.023 to - 0.001, P = 0.036) affected the BMI value together in these lactating women. In conclusion, dietary serine and SAAs were found to directly affect the nutritional status, and both high protein intake and low plasma SEPP1 might be the health risks in these lactating Chinese women.

Breast milk selenocystine as a biomarker for selenium intake in lactating women at differential geographical deficiency risk in China.

BACKGROUND AND OBJECTIVES: A reliable biomarker for optimal selenium (Se) intake in lactating women is not currently available. METHODS AND STUDY DESIGN: Daily dietary Se intake in lactating women was calculated from a 24-hour meal record survey for over 3 days. Se levels in plasma and breast milk were measured through inductively coupled plasma mass spectrometry. Plasma selenoprotein P 1 levels and glutathione peroxidase 3 activity were measured using an enzyme-linked immunosorbent assay. Ultra-performance liquid chromatography-tandem mass spectrometry was used to analyze proteinaceous Se species in enzymatically digested breast milk. RESULTS: Dietary Se intakes of lactating women from Liangshan, Beijing, and Enshi were 41.6±21.2 ng/d, 51.1±22.6 ng/d, and 615±178 ng/d, respectively (p<0.05). The Se levels in the blood and breast milk were significantly associated with the dietary Se intake (p<0.05). The proteinaceous Se species in breast milk were SeMet and SeCys2. The levels of SeMet in the lactating women from Liangshan, Beijing, and Enshi were 3.31±2.44 ng Se/mL, 7.34±3.70 ng Se/mL, and 8.99±9.64 ng Se/mL, while that of SeCys2 were 13.7±12.0 ng Se/mL, 35.6±20.9 ng Se/mL, and 57.4±13.2 ng Se/mL, respectively. Notably, the concentration of SeCys2, the metabolite of unstable SeCys, reached a saturation platform, whereas no similar phenomenon were found for the total Se SeMet from Secontaining proteins. CONCLUSIONS: SeCys2 in breast milk is a potential biomarker for determining the optimal Se intake in lactating women.

Calculation of an Adequate Intake (AI) Value and Safe Range of Selenium (Se) for Chinese Infants 0-3 Months Old Based on Se Concentration in the Milk of Lactating Chinese Women with Optimal Se Intake.

The required selenium intake for optimal health in Chinese residents was published in 2014. However, the adequate intake (AI) value for Chinese infants 0-3 months old is not established. This study assessed the current selenium nutritional status of 264 lactating Chinese women from three geographical locations with different Se levels (Liangshan in Sichuan province, Enshi in Hubei province, and Xicheng District in Beijing), to screen mothers with optimal Se intake, and to modify the AI value of Se for Chinese infants 0-3 months old. Milk and plasma Se concentrations were determined by inductively coupled plasma mass spectrometry (ICP-MS) and glutathione peroxidase 3 (GPx3), and plasma selenoprotein P (SEPP1) was measured by ELISA. Daily Se intake (Y, µg/day) in lactating Chinese woman was calculated from plasma Se concentrations (X, µg/L) using the formula logY = 1.623 log(X) + 3.433. Plasma Se concentrations in lactating Chinese women were 78.19 ± 25.71, 112.48 ± 24.57, and 183.83 ± 45.81 µg/L from Se-deficient, Se-moderate, and seleniferous areas, respectively. Se intakes calculated from concentrations of plasma Se were 45.6 ± 21.69, 80.03 ± 27.69, and 223.10 ± 50.95 µg/day, respectively. An optimal dietary Se intake is not lower than the recommended nutrient intake (RNI) but not more than the tolerable upper intake level (UL). A range of 78-400 µg Se/day was defined as the optimal daily Se intake for lactating Chinese women. The percentages of mothers within this range in Sichuan, Beijing, and Enshi were 8.11, 45.13, and 6.06%, respectively. Based on milk Se concentrations of mothers with optimal daily Se intake, the adequate Se intake value and a safe range for Chinese infants 0-3 months of age were calculated as 15.29 and 8-35 µg Se/day, respectively. The Se status of Chinese lactating women has improved, particularly in traditionally Se-deficient and Se-toxic regions. A safe range for daily Se intake in Chinese infants may be regarded as a guideline for infant formula.