Selenium and breast-feeding

Supplementation of the maternal diet with Brazil nut (Bertholletia excelsa H.B.K.) prevents cognitive impairment in the offspring of obese mothers

Maternal obesity may trigger long-term neurodevelopmental disorders in offspring. Considering the benefits of the Brazil nut (Bertholletia excelsa H.B.K.), a rich source of nutrients such as selenium, this study aimed to evaluate its effect on the behavior of obese rat offspring and its relationship with oxidative stress. From 60 days of age until weaning, female Wistar rats were fed a high-fat diet (mHF) or an HF diet supplemented with 5% Brazil nut (mHF/BN), while control mothers (mCTL) were fed a standard diet or a standard diet supplemented with 5% Brazil nut (mBN). Male pups received a standard diet throughout life and, at 30 and 90 days old, were subjected to behavioral tasks to evaluate anxiety and cognition. Biochemical evaluations were performed at 90 days of age. No alterations were observed in the anxiety behavior of the offspring. However, the offspring of the mHF group (oHF) exhibited impaired short-term memory at 30 and 90 days of age and impaired long-term memory at 30 days. Short-term memory impairment was prevented by Brazil nuts in young rats (30 days). While the serum selenium concentration was reduced in the oHF group, the serum catalase concentration was reduced in all groups, without changes in lipid peroxidation or protein carbonylation. Brazil nut maternal diet supplementation prevented short- and long-term cognitive impairment in the offspring, which may be related to the selenium levels.

Selenium in Infants and Preschool Children Nutrition: A Literature Review

Selenium (Se), an essential trace element, is fundamental to human health, playing an important role in the formation of thyroid hormones, DNA synthesis, the immune response, and fertility. There is a lack of comprehensive epidemiological research, particularly the serum Se concetration in healthy infants and preschool children compared to the estimated dietary Se intake. However, Se deficiencies and exceeding the UL have been observed in infants and preschool children. Despite the observed irregularities in Se intake, there is a lack of nutritional recommendations for infants and preschool children. Therefore, the main objective of this literature review was to summarize what is known to date about Se levels and the risk of deficiency related to regular consumption in infants and preschool children.

Associations of Dietary Intake and Nutrient Status with Micronutrient and Lipid Composition in Breast Milk of Donor Women

The influence of the diet and nutritional status of milk donors on the nutritional composition of donor human milk (DHM) is unknown. The present study aimed to determine the nutritional profile of DHM and the associations between donors' dietary intake and nutritional status and the micronutrient and lipid composition in DHM. For this purpose, 113 donors completed a food frequency questionnaire, provided a five-day weighed dietary record, and collected milk for five consecutive days. Nutrient determinations in donors' erythrocytes, plasma, urine, and milk were performed. Multiple linear regressions were conducted for the evaluation of the associations. We highlight the following results: DHM docosahexaenoic acid (DHA) was positively associated with donors' plasma DHA content and donors' DHA intake (R2 0.45, p < 0.001). For every 1 g/day DHA intake, an increase of 0.38% in DHA content and 0.78% in total omega-3 content was observed in DHM (R2 0.29, p < 0.001). DHM saturated fatty acids were positively associated with erythrocyte dimethyl acetals, plasma stearic acid, trans fatty acids intake, and breastfeeding duration and negatively associated with erythrocyte margaroleic acid (R2 0.34, p < 0.01). DHM cholecalciferol was associated with plasma cholecalciferol levels and dairy intake (R2 0.57, p < 0.01). Other weaker associations were found for free thiamin, free riboflavin, pyridoxal, dehydroascorbic acid, and the lipid profile in DHM. In conclusion, the diet and nutritional status of donors influence the fatty acid profile and micronutrient content of DHM.

Correlation of maternal dietary intake with breast milk composition and infant growth

Background: Maternal dietary intake during the period of lactation has an impact on infants growth. Macronutrients in breast milk are affected by several factors such as maternal dietary intake and maternal nutritional status. This study aims to prove the association between maternal protein and fat intake with the composition of breast milk and growth of infants (age 0-6 months). Methods: Prospective study was conducted for 6 months in 41 mother-infant pairs who were exclusively breastfed, and visited to hospitals or health centres. The mothers age is <40 years old with normal and single pregnancy. The breast milk was collected and analyzed using Human Milk Analyzer. Results: There was a negative correlation between maternal protein intake and breast milk composition at 3 months old infants (p = 0.042), between fat intake with HAZ score at 2 weeks (p = 0.048), and between protein intake with HAZ score at 3 months (p = 0.049). Finally, there was a significant increase in WAZ and HAZ score in all sample groups. Although the maternal protein intake of our subjects were only at 83% of Indonesian's RDA average, the protein composition of breast milk and the growth of the infants was sufficient. Conclusion: There is correlation between maternal dietary intake with the composition of breastmilk and infant growth. Even though the calories and protein intake of the mother is lower than the RDA, the breast milk is still sufficient for the growth of infants aged 0-6 months who are exclusively breastfed.

Human milk: From complex tailored nutrition to bioactive impact on child cognition and behavior

Human milk is a highly complex liquid food tailor-made to match an infant's needs. Beyond documented positive effects of breastfeeding on infant and maternal health, there is increasing evidence that milk constituents also impact child neurodevelopment. Non-nutrient milk bioactives would contribute to the (long-term) development of child cognition and behavior, a process termed 'Lactocrine Programming'. In this review we discuss the current state of the field on human milk composition and its links with child cognitive and behavioral development. To promote state-of-the-art methodologies and designs that facilitate data pooling and meta-analytic endeavors, we present detailed recommendations and best practices for future studies. Finally, we determine important scientific gaps that need to be filled to advance the field, and discuss innovative directions for future research. Unveiling the mechanisms underlying the links between human milk and child cognition and behavior will deepen our understanding of the broad functions of this complex liquid food, as well as provide necessary information for designing future interventions.

Human Milk Oligosaccharide Compositions Illustrate Global Variations in Early Nutrition

BACKGROUND

Human milk oligosaccharides (HMOs) are an abundant class of compounds found in human milk and have been linked to the development of the infant, and specifically the brain, immune system, and gut microbiome.

OBJECTIVES

Advanced analytical methods were used to obtain relative quantitation of many structures in approximately 2000 samples from over 1000 mothers in urban, semirural, and rural sites across geographically diverse countries.

METHODS

LC-MS-based analytical methods were used to profile the compounds with broad structural coverage and quantitative information. The profiles revealed their structural heterogeneity and their potential biological roles. Comparisons of HMO compositions were made between mothers of different age groups, lactation periods, infant sexes, and residing geographical locations.

RESULTS

A common behavior found among all sites was a decrease in HMO abundances during lactation until approximately postnatal month 6, where they remained relatively constant. The greatest variations in structural abundances were associated with the presence of α(1,2)-fucosylated species. Genomic analyses of the mothers were not performed; instead, milk was phenotyped according to the abundances of α(1,2)-fucosylated structures. Mothers from the South American sites tended to have higher proportions of phenotypic secretors [mothers with relatively high concentrations of α(1,2)-fucosylated structures] in their populations compared to the rest of the globe, with Bolivia at ∼100% secretors, Peru at ∼97%, Brazil at ∼90%, and Argentina at ∼85%. Conversely, the cohort sampled in Africa manifested the lowest proportion of secretors (South Africa ∼ 63%, the Gambia ∼ 64%, and Malawi ∼ 75%). Furthermore, we compared total abundances of HMOs in secretors compared with nonsecretors and found that nonsecretors have lower abundances of HMOs compared to secretors, regardless of geographical location. We also observed compositional differences of the 50+ most abundant HMOs between milk types and geographical locations.

CONCLUSIONS

This study represents the largest structural HMO study to date and reveals the general behavior of HMOs during lactation among different populations.

Infant Iodine and Selenium Status in Relation to Maternal Status and Diet During Pregnancy and Lactation

Iodine and selenium are essential trace elements. Recent studies indicate that pregnant and lactating women often have insufficient intake of iodine and selenium, but the impact on fetal and infant status is unclear. Here, we assessed iodine and selenium status of infants in relation to maternal intake and status of these trace elements in the birth cohort NICE, conducted in northern Sweden (n = 604). Iodine was measured in urine (UIC) in gestational week 29, and in breast milk and infant urine 4 months postpartum, while selenium was measured in maternal plasma and erythrocytes in gestational week 29, and in breast milk and infant erythrocytes 4 months postpartum, in both cases using ICP-MS. Maternal intake was assessed with semi-quantitative food frequency questionnaires in gestational week 34 and at 4 months postpartum. The median intake of iodine and selenium during pregnancy (98 and 40 μg/d, respectively) and lactation (108 and 39 μg/d, respectively) was below recommended intakes, reflected in insufficient status (median UIC of 113 μg/L, median plasma selenium of 65 μg/L). Also, breast milk concentrations (median iodine 77 μg/L, median selenium 9 μg/L) were unlikely to meet infant requirements. Median UIC of the infants was 114 μg/L and median erythrocyte selenium 96 μg/kg, both similar to the maternal concentrations. Infant UIC correlated strongly with breast milk levels (rho = 0.64, p < 0.001). Their erythrocyte selenium correlated with maternal erythrocyte selenium in pregnancy (rho = 0.38, p < 0.001), but not with breast milk selenium, suggesting formation of prenatal reserves. Our results indicate that the transport of iodine and selenium to the fetus and infant is prioritized. Still, it is uncertain whether most infants had sufficient intakes. Further, the results might indicate an involvement of iodine in asthma development during the first year of life, which is essential to follow up. The low maternal and infant dietary intake of both iodine and selenium, especially when the mothers did not use supplements or iodized table salt, suggest a need for a general screening of women and young children.

Effect of selenium-free parenteral nutrition on serum selenium of neonates and infants maintained on long-term parenteral nutrition

BACKGROUND

The risk of selenium deficiency increases for infants receiving long-term parenteral nutrition (PN). This study analyzed selenium deficiency in neonates and infants requiring long-term PN and evaluated the effect of intravenous (IV) selenium provision.

METHODS

This study was a retrospective study of neonates and infants who were admitted to a neonatal intensive care unit from January 2010 to December 2019, received PN for ≥2 weeks, and had their serum selenium concentration measured. Patients were divided into two groups, depending on their serum selenium concentration, a deficient group (n = 55) and a nondeficient group (n = 47).

RESULTS

Of the study participants, 53.9% (55 of 102) were deficient in selenium. No difference in demographic and clinical characteristics existed except bronchopulmonary dysplasia. A subgroup analysis was performed for patients (n = 29). The average dose of IV selenium administered to patients was 2.7 ± 1.0 mcg/kg/day. The average initial serum selenium concentration was 36.5 ± 18.0 mcg/L, and the serum concentration significantly increased to 52.5 ± 19.1 mcg/L after IV selenium administration (P < .001). The correlation between the average IV selenium dose and the change in serum selenium concentrations was statistically significant (r = .423; P = .022).

CONCLUSION

Selenium deficiency is common in neonates and infants receiving long-term PN. Serum selenium concentration increased proportionally as the IV selenium dose increased. Therefore, it is recommended to supply a proper dose of IV selenium depending on the degree of selenium deficiency.

Fetal Programming Is Deeply Related to Maternal Selenium Status and Oxidative Balance; Experimental Offspring Health Repercussions

Nutrients consumed by mothers during pregnancy and lactation can exert permanent effects upon infant developing tissues, which could represent an important risk factor for diseases during adulthood. One of the important nutrients that contributes to regulating the cell cycle and tissue development and functionality is the trace element selenium (Se). Maternal Se requirements increase during gestation and lactation. Se performs its biological action by forming part of 25 selenoproteins, most of which have antioxidant properties, such as glutathione peroxidases (GPxs) and selenoprotein P (SELENOP). These are also related to endocrine regulation, appetite, growth and energy homeostasis. In experimental studies, it has been found that low dietary maternal Se supply leads to an important oxidative disruption in dams and in their progeny. This oxidative stress deeply affects gestational parameters, and leads to intrauterine growth retardation and abnormal development of tissues, which is related to endocrine metabolic imbalance. Childhood pathologies related to oxidative stress during pregnancy and/or lactation, leading to metabolic programing disorders like fetal alcohol spectrum disorders (FASD), have been associated with a low maternal Se status and intrauterine growth retardation. In this context, Se supplementation therapy to alcoholic dams avoids growth retardation, hepatic oxidation and improves gestational and breastfeeding parameters in FASD pups. This review is focused on the important role that Se plays during intrauterine and breastfeeding development, in order to highlight it as a marker and/or a nutritional strategy to avoid diverse fetal programming disorders related to oxidative stress.

Prenatal dietary diversity may influence underweight in infants in a Ugandan birth-cohort

Growth faltering in early childhood is prevalent in many low resource countries. Poor maternal dietary diversity during pregnancy has been linked with increased risk of fetal growth failure and adverse birth outcomes but may also influence subsequent infant growth. Our aim is to assess the role of prenatal maternal dietary diversity in infant growth in rural Uganda. Data from 3291 women and infant pairs enrolled in a birth cohort from 2014 to 2016 were analysed (NCT04233944). Maternal diets were assessed using dietary recall in the second or third trimesters of pregnancy. Maternal dietary diversity scores (DDS) were calculated using the FAO Minimum Dietary Diversity for Women (MDD‐W). Cox regression models were used to evaluate associations of the DDS with the incidence of underweight, stunting and wasting in infants from 3 to 12 months, adjusting for confounding factors. The median DDS for women was low, at 3.0 (interquartile range 3.0–4.0), relative to the threshold of consuming five or more food groups daily. Infants of women in highest quartile of DDS (diverse diets) were less likely to be underweight (adjusted hazard ratio: 0.70, 95% confidence interval: 0.61, 0.80) compared with infants of women in Quartile 1 (p for trend <0.001) in models controlling for maternal factors. There was no significant association between DDS and stunting or wasting. Our findings suggest a relationship between higher maternal dietary diversity and lower risk of underweight in infancy. These findings suggest that programmes to improve infant growth could additionally consider strengthening prenatal dietary diversity to improve child outcomes globally.

Nutritional supplements and mother's milk composition: a systematic review of interventional studies

Background

This study aims to systematically review the effects of maternal vitamin and/or mineral supplementation on the content of breast milk.

Methods

We systematically searched electronic databases including Medline via PubMed, Scopus and ISI Web of Science till May 24, 2018. The following terms were used systematically in all mentioned databases: (“human milk” OR “breast milk” OR “breast milk composition” OR “human breast milk composition” OR “composition breast milk” OR “mother milk” OR “human breast milk” OR “maternal milk”) AND (“vitamin a” OR “retinol” OR “retinal” OR “retinoic acid” OR “beta-carotene” OR “beta carotene” OR “ascorbic acid” OR “l-ascorbic acid” OR “l ascorbic acid” OR “vitamin c” OR “vitamin d” OR “cholecalciferol” OR “ergocalciferol” OR “calciferol” OR “vitamin e” OR “tocopherol” OR “tocotrienol” OR “alpha-tocopherol” OR “alpha tocopherol” OR “α-tocopherol” OR “α tocopherol” OR “vitamin k” OR “vitamin b” OR “vitamin b complex” OR “zinc” OR “iron” OR “copper” Or “selenium” OR “manganese” OR “magnesium”) and we searched Medline via Medical subject Headings (MeSH) terms. We searched Google Scholar for to increase the sensitivity of our search. The search was conducted on human studies, but it was not limited to the title and abstract. Methodological quality and risk of bias of included studies were evaluated by Jadad scale and Cochrane risk of bias tools, respectively.

Results

This review included papers on three minerals (zinc, iron, selenium) and 6 vitamins (vitamin A, B, D, C, E and K) in addition to multi-vitamin supplements. Although studies had different designs, e.g. not using random allocation and/or blinding, our findings suggest that maternal use of some dietary supplements, including vitamin A, D, vitamin B1, B2 and vitamin C might be reflected in human milk. Vitamin supplements had agreater effect on breast milk composition compared to minerals. Higher doses of supplements showed higher effects and they were reflected more in colostrum than in the mature milk.

Conclusion

Maternal dietary vitamin and/or mineral supplementation, particularly fat- soluble vitamins, vitamin B1, B2 and C might be reflected in the breast milk composition. No difference was found between mega dose and single dose administration of minerals.

Investigation of amino acids and minerals in Chinese breast milk

BACKGROUND

The nutrients in human milk, particularly amino acids and minerals, are important for infant growth and development. Since there are few reports of amino acids and minerals in Chinese breast milk, we conducted this study to establish a representative preliminary database of breast milk nutrients in Chinese breast milk. In this study, we collected breast milk from healthy mothers in seven cities in western, southern and central China. The composition, content and proportion of total amino acids and ten elements (potassium, sodium, calcium, magnesium, iron, zinc, manganese, copper, selenium and phosphorus) in human milk in different lactation stages were investigated.

RESULTS

In this study, it was found that the content of total essential amino acids (671.47 mg 100 mL^-1 ) in Chinese breast milk was higher compared with the European Society for Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN) (574 mg 100 mL^-1 ), but the content of leucine (LEU) (129.01 mg 100 mL^-1 ) and cysteine (CYS) (20.31 mg 100 mL^-1 ) was much lower than that recommended by ESPGHAN. Moreover, it was found that the content of most of these ten elements decreased during lactation, and the content of calcium in Chinese breast milk was lower compared with ESPGHAN. In addition, the content of selenium (7.23-20.55 mg 1000 mL^-1 ) in breast milk from the three cities Nanchang, Shanghai and Guangzhou in China was much higher than that recommended by ESPGHAN.

CONCLUSIONS

In a word, amino acids and minerals in Chinese human milk showed a significant difference from other countries. Human milk meal or infant food should be regulated to meet the requirements of the infant and to maintain the balance of the amino acids and minerals. © 2020 Society of Chemical Industry.

Selenium intake and status of postpartum women and postnatal depression during the first year after childbirth in New Zealand - Mother and Infant Nutrition Investigation (MINI) study

BACKGROUND

Selenium (Se) plays an important role in selenoproteins as an antioxidant, and is involved in thyroid function, mental health and child development. Selenium is low in the local food supplies in NZ. Low selenium intake has been reported in women of childbearing age and postmenopausal women, however, there is little research relating to breastfeeding women and their infants.

PURPOSE

The study investigates maternal and infant selenium intake and status during the first year postpartum, and possible relationships to postnatal depression and anxiety.

BASIC PROCEDURES

The Mother and Infant Nutrition Investigation (MINI) study is an observational longitudinal cohort study. In total 87 breastfeeding mother-infant pairs were recruited and followed up at 3, 6 and 12 months postpartum. Maternal selenium intake was estimated from a four-day diet diary (4DDD). Selenium concentrations were measured in maternal spot urine, breastmilk and plasma; and infant spot urine samples. Postnatal depression was screened by the Edinburgh Postnatal Depression Scale (EPDS) questionnaire.

MAIN FINDINGS

Median maternal selenium intake was 62 (50, 84) μg/day, with 56 % below the Estimated Average Requirement (EAR) of 65 μg/day. At 3, 6, and 12 months postpartum, median maternal urinary selenium:creatinine ratios were 29.0 (22.4, 42.0), 29.5 (23.1, 28.4), and 30.9 (24.3, 35.3) μg/g; median infant urinary selenium concentrations (IUSC) were 8 (6,13), 11 (6, 15), and 24 (10, 40) μg/L; median breastmilk selenium concentrations (BMSC) were 13 (11, 14), 11 (9, 11) and 12 (11, 13) μg/L; 18 %, 11 % and 14 % of women reported probable minor depression based on the EPDS scores equal or above 10. Estimated median infant selenium intake at 3 and 6 months were 9 (8, 11) and 8 (7, 10) μg/day with 85 % and 93 % below the Adequate Intake of 12 μg/day. Median maternal plasma selenium was 105.8 μg/L at 6 months postpartum. Minor depression at three months postpartum was significantly different across tertiles of plasma selenium concentrations (p = 0.041).

PRINCIPLE CONCLUSIONS

Suboptimal selenium intake was observed among breastfeeding mothers and their infants in the MINI study. Potentially, some women had insufficient selenium status. Relation between selenium status and risk of postnatal depression and anxiety was inconclusive.Further research is required to explore effects on maternal thyroid function and infant neurodevelopment among women with inadequate selenium intake and status.

Green and simple extraction of free seleno-amino acids from powdered and lyophilized milk samples with natural deep eutectic solvents

Natural deep eutectic solvents (NADES) were introduced for the extraction of free seleno-amino acids from lyophilized and powdered milk samples. Different NADES were evaluated, and lactic acid:glucose (LGH) showed the highest selenium recoveries. Selenium analysis was performed by inductively coupled plasma mass spectrometry (ICP MS). Se-NADES analysis in ICP MS was optimized according to the radio frequency power and nebulization gas flow rate. Se-NADES extraction was optimized by an experimental design. LGH dilution, LGH volume, sample quantity, and ultrasound time were factors influencing the extraction. Seleno-amino acids were determined by liquid chromatography-ICP MS. After optimization, the limits of detection obtained were 7.37, 8.63, and 9.64 µg kg^-1 for selenocysteine, selenomethionine, and seleno-methyl-selenocysteine, respectively. The NADES-extraction is a green procedure with 2 penalty points in the EcoScale. The method was applied to the analysis of powdered milk, lyophilized Se-fortified sheep milk, and ERM-BD151 skimmed milk powder.

Selenium biofortified alfalfa hay fed in low quantities improves selenium status and glutathione peroxidase activity in transition dairy cows and their calves

The hypothesis of the study was that feeding a relatively low amount of Se biofortified alfalfa hay during the dry period and early lactation would improve selenium status and glutathione peroxidase activity in dairy cows and their calves. Ten Jersey and 8 Holstein primiparous dairy cows were supplemented with Se biofortified (TRT; n = 9) or non-biofortified (CTR; n = 9) alfalfa hay at a rate of 1 kg/100 kg of BW mixed with the TMR from 40 d prior parturition to 2 weeks post-partum. Se concentration in whole blood, liver, milk, and colostrum, the transfer of Se to calves, and the glutathione peroxidase (GPx) activity were assessed. TRT had 2-fold larger (P < 0.05) Se in blood v. CTR that resulted in larger Se in liver and colostrum but not milk and larger GPx activity in plasma and erythrocytes but not in milk. Compared to CTR, calves from TRT had larger Se in blood but only a numerical (P = 0.09) larger GPx activity in plasma. A positive correlation was detected between Se in the blood and GPx activity in erythrocytes and plasma in cows. Our results demonstrated that feeding pregnant primiparous dairy cows with a relatively low amount of Se-biofortified alfalfa hay is an effective way to increase Se in the blood and liver, leading to greater antioxidant activity via GPx. The same treatment was effective in improving Se concentration in calves but had a modest effect on their GPx activity. Feeding Se biofortified hay increased Se concentration in colostrum but not in milk.

A novel HPLC column switching method coupled to ICP-MS/QTOF for the first determination of selenoprotein P (SELENOP) in human breast milk

In this work, we describe for the first time the presence of selenoprotein P in human breast milk. To this end, a novel analytical method has been developed based on a two-dimensional column switching system, which consisted of three size exclusion columns and one affinity column coupled to inductively coupled plasma mass spectrometry (ICP-MS). The method combines the accurate quantification of selenoproteins and selenometabolites by species unspecific isotopic dilution ICP-MS, with unequivocal identification by quadrupole-time-of-flight mass spectrometry. Several selenopeptides, which contain the amino acid selenocysteine (U, SeCys), were identified after tryptic digestion followed by their separation. The results reveal that the relative selenium concentration in colostrum follows the order: glutathione peroxidase (GPX) ≈ selenoprotein P (SELENOP) > selenocystamine (SeCA) > other selenometabolites (SeMB), in contrast with previously published papers (GPX > SeCA > selenocystine > selenomethionine). A mean concentration of 20.1 ± 1.0 ng Se g^-1 as SELENOP (1.45 μg SELENOP/g) was determined in colostrum (31% of total selenium).

Anthropometry before Day 46 and Growth Velocity before 6 Months of Guatemalan Breastfed Infants Are Associated with Subclinical Mastitis and Milk Cytokines, Minerals, and Trace Elements

BACKGROUND

Subclinical mastitis (SCM) is an inflammatory condition of the mammary gland, but its association with human milk composition and infant growth is not well described.

OBJECTIVES

We investigated whether SCM, milk cytokines, and/or estimated intakes of milk minerals and trace elements were associated with infant anthropometry or growth velocity before 6 mo.

METHODS

Breast milk was collected from Mam-Mayan mothers (n = 114) at both early (2-46 d) and established (4-6 mo) lactation. Concentrations of 9 elements (sodium, potassium, calcium, magnesium, copper, iron, manganese, selenium, zinc) analyzed by inductively-coupled plasma mass spectrometry were used to estimate infants' daily intakes. Concentrations of 4 cytokines were measured. Milk concentrations and infants' estimated elemental intakes and anthropometric measurements during early and established lactation were compared by SCM status. Multiple regression was used to identify factors associated with infant growth attainment (<46 d) for infant weight- (WAZ), length- (LAZ), and head circumference-for-age (HCAZ) and weight-for-length (WLZ) z scores and with growth velocity (expressed as Δ/d) from early to established lactation.

RESULTS

SCM prevalence was higher in early (30%) than established (10%) lactation. Breast milk of SCM mothers had higher cytokine concentrations and higher magnesium in early and higher selenium concentrations in both early and established lactation (Padj < 0.0121). At day 46, regression models showed inverse associations of SCM with WLZ and IL-1β with LAZ (Padj < 0.0150). In contrast, linear growth velocity was positively associated with IL-1β measured in early lactation (Padj < 0.0124), whereas cranial growth velocity was positively associated with IL-8 measured during established lactation ( Padj < 0.0124).

CONCLUSIONS

Despite a high prevalence of inadequate intakes, only infants' intake of milk magnesium during early lactation was associated with linear growth velocity in breastfed infants <6 mo. Evidence shows that SCM, breast-milk cytokines, and infants' estimated intakes of select elements are independently associated with growth attainment and growth velocity during lactation.

Selenium Intake in Iodine-Deficient Pregnant and Breastfeeding Women in New Zealand

Selenium plays a role in antioxidant status and, together with iodine, in thyroid function. Iodine deficiency exists in New Zealand during pregnancy and lactation, and selenium deficiency may further affect thyroid function. This study investigated selenium intakes of pregnant and lactating women, in Palmerston North, in the North Island of New Zealand. Dietary intake was estimated using three repeated 24-h dietary recalls. Dietary intake in pregnancy was also estimated from 24-h urinary excretion of selenium. Selenium concentrations were determined in urine and breastmilk using inductively-coupled plasma mass spectrometry. Median selenium intakes based on dietary data were 51 (39, 65) μg/day in pregnancy and 51 (36, 80) μg/day in lactation, with 61% and 68% below estimated average requirement (EAR). Median daily selenium intake in pregnancy based on urinary excretion was 49 (40, 60) µg/day, with 59% below EAR. Median selenium concentration in breastmilk was 11 (10, 13) µg/L and estimated median selenium intake for infants was 9 (8, 10) µg/day, with 91% below the Adequate Intake of 12 μg/day. These pregnant and breastfeeding women were at risk of dietary selenium inadequacy. Further research is required to assess selenium status in relation to thyroid function and health in this group.

Are breast milk adipokines affected by maternal dietary factors?

Background Maternal diet and gestational age of infant may affect the composition of breast milk. The aim of this study was to evaluate the relationship between breast milk adiponectin and leptin levels of mothers delivering preterm and term infants and maternal diet. Methods Sixty-five mothers (31 preterm, 34 term) were included in the study. General information about parents and infants and food consumption of mothers were determined through a questionnaire. Milk samples were taken from mothers during the period between the 15th and 30th day after birth (mature milk). For the evaluation of maternal diet, the nutrient adequacy ratio (NAR) and mean adequacy ratio (MAR) were used. Results According to MAR, 71.0% of preterm mothers' and 79.4% of term mothers' dietary adequacy was categorized as "good", and none of the mothers fell into the "insufficient" category (p>0.05). The median (interquartile range [IQR]) level of adipokines was found to be higher in preterm than in term mothers (24.6 [14.3] ng/mL; 22.9 [9.7] ng/mL for adiponectin and 2.0 [2.5] ng/mL; 0.0 [2.3] ng/mL for leptin, respectively) (p>0.05). A negative correlation was found between the leptin level and intake of unsaturated fatty acids, protein NAR and meat, poultry and fish consumption in preterm mothers (p<0.05). A positive correlation was found between leptin concentration and MAR, protein, calcium, potassium NAR and consumption of dairy products in term mothers (p<0.05). In the regression model, gestational age and MAR are important predictors of leptin. Conclusions These results show that maternal diet is related to the leptin content in breast milk.

Maternal selenium status and neuropsychological development in Spanish preschool children

BACKGROUND

The relationship between maternal selenium (Se) status and child neurodevelopment has been scarcely assessed. In a previous study we observed an inverse U-shaped association between maternal Se concentrations and infant neurodevelopment at 12 months of age. In this study, this non-linear association was explored at preschool age. The effect modification by breastfeeding, child's sex and cord blood mercury was also evaluated.

METHODS

Study subjects were 490 mother-child pairs from the Spanish Childhood and Environment Project (INMA, 2003-2012). Child neuropsychological development was assessed at around 5 years of age by the McCarthy Scales of Children's Abilities (MSCA). Sociodemographic and dietary characteristics were collected by questionnaire at the first and third trimester of gestation and at 5 years of age. Se was measured in serum samples by ICP-MS at the end of the first trimester of pregnancy (mean ± standard deviation (SD) = 12.4 ± 0.6 weeks of gestation).

RESULTS

The mean ± SD of maternal serum Se concentrations was 79.9 ± 8.1 µg/L. In multivariate analysis, no linear association was found between Se concentrations and the nine MSCA scales. Generalized additive models indicated inverted U-shaped relationships between Se concentrations and the verbal and global memory scales. When assessing the influence of effect modifiers, breastfeeding played a role: the association between Se and neuropsychological development was inverted U-shaped for the quantitative, general cognitive, working memory, fine motor, global motor and executive function scales only for non-breastfed children.

CONCLUSION

Low and high maternal Se concentrations seem to be harmful for child neuropsychological development, however further studies should explore this non-linear relationship.

Selenium fortification of infant formulas: does selenium form matter?

Selenium is a trace element essential for the health and development of the growing infant. It is a necessary component of proteins and enzymes required for a variety of functions, including antioxidant defense, modulation of the inflammatory response, and production of thyroid hormones. In breast-fed infants, selenium stores depend on the selenium content of the mother's diet. In formula-fed infants, selenium levels are correlated to the residual selenium stores accumulated in utero and the level and type of selenium fortification used in the formula. Today, the United States Food and Drug Administration (FDA) recommends that infant formulas contain selenium at levels between 2.0 and 7.0 μg per 100 kcal. While the US FDA does not recommend a particular selenium form for fortification, evidence indicates that organically bound selenium forms (e.g., selenomethionine and selenium-enriched yeast) are better absorbed and retained than inorganic forms (e.g., selenite and selenate). Preliminary data from studies in adults do suggest that fortification with standardized selenium-enriched yeast may offer benefits compared to fortification with other organically bound selenium forms. However, because most studies evaluating the impact of selenium fortification of infant formula have assessed inorganic selenium supplements, additional research into the bioavailability and outcomes associated with the use of selenium-enriched yeast in infants is needed.

Overview of Nutrients in Human Milk

The WHO recommends exclusive breastfeeding for the first 6 mo of life to promote optimal infant health and development. Understanding the micro- and macronutrient concentrations of human milk and how each nutrient fluctuates with lactational stage, maternal factors, and supplementation is imperative for supporting good breastfeeding practices. Where maternal undernutrition compromises human milk quality, a thorough awareness of the effectiveness of interventions can direct efforts to achieve both maternal and infant nutrient sufficiency. This review of current knowledge covers trends in nutrient concentrations over the course of lactation and describes the influence of maternal intake, status, supplementation, and other factors on human milk concentrations of each nutrient.

They Are What You Eat: Can Nutritional Factors during Gestation and Early Infancy Modulate the Neonatal Immune Response?

The ontogeny of the human immune system is sensitive to nutrition even in the very early embryo, with both deficiency and excess of macro- and micronutrients being potentially detrimental. Neonates are particularly vulnerable to infectious disease due to the immaturity of the immune system and modulation of nutritional immunity may play a role in this sensitivity. This review examines whether nutrition around the time of conception, throughout pregnancy, and in early neonatal life may impact on the developing infant immune system.

Impact of Maternal Selenium Status on Infant Outcome during the First 6 Months of Life

Pregnant women and infants are at risk for selenium deficiency, which is known to have negative effects on immune and brain function. We have investigated selenium levels in 158 healthy never-pregnant women and in 114 pregnant and lactating women and their infants at age 6 months and related this to clinical outcomes during the first 6 months of life. Neurodevelopment was assessed with the parental questionnaire Ages and Stages (ASQ) at 6 months. A maternal selenium level ≤0.90 µmol/L in pregnancy week 18 was negatively related to infant neurodevelopment at 6 months (B = -20, p = 0.01), whereas a selenium level ≤0.78 µmol/L in pregnancy week 36 was associated with an increased risk (odds ratio 4.8) of having an infant infection during the first 6 weeks of life. A low maternal selenium status in pregnancy was found to be associated with an increased risk of infant infection during the first 6 weeks of life and a lower psychomotor score at 6 months. We suggest a cutoff for maternal serum selenium deficiency of 0.90 µmol/L in pregnancy week 18 and 0.78 µmol/L in pregnancy week 36. This should be reevaluated in an intervention study.

Impact of maternal nutrition on breast-milk composition: a systematic review

BACKGROUND

It is widely reported that maternal diet influences the nutritional composition of breast milk. The amount of variability in human milk attributable to diet remains mostly unknown. Most original studies that reported a dietary influence on breast-milk composition did not assess diet directly, did not quantify its association with milk composition, or both.

OBJECTIVE

To gather the quantitative evidence on this issue, we carried out a systematic PubMed and Medline search of articles published up to January 2015 and filtered the retrieved articles according to predefined criteria.

DESIGN

Only studies that provided quantitative information on both maternal diet and milk data, measured in individual healthy mothers of healthy term infants and based on an original observational or experimental design, were included. Exclusion criteria were a focus on supplements, transfer of toxic metals or other contaminants from diet to milk, or on marginally nourished women.

RESULTS

Thirty-six publications-including data on 1977 lactating women-that matched our criteria were identified. Seventeen studies investigated dietary effects on fatty acids in breast milk. The rest included studies that focused on a diverse spectrum of other nutritional properties of breast milk. The largest evidence, in terms of number of articles, for any link between maternal diet and a nutritive property of breast milk came from 3 studies that supported the link between fish consumption and high docosahexaenoic acid in breast milk and 2 studies that reported a positive correlation between dietary vitamin C and milk concentrations of this vitamin.

CONCLUSIONS

The available information on this topic is scarce and diversified. Most of the evidence currently used in clinical practice to make recommendations is limited to studies that only reported indirect associations.

Plasma and breast-milk selenium in HIV-infected Malawian mothers are positively associated with infant selenium status but are not associated with maternal supplementation: results of the Breastfeeding, Antiretrovirals, and Nutrition study

BACKGROUND

Selenium is found in soils and is essential for human antioxidant defense and immune function. In Malawi, low soil selenium and dietary intakes coupled with low plasma selenium concentrations in HIV infection could have negative consequences for the health of HIV-infected mothers and their exclusively breastfed infants.

OBJECTIVE

We tested the effects of lipid-based nutrient supplements (LNS) that contained 1.3 times the Recommended Dietary Allowance of sodium selenite and antiretroviral drugs (ARV) on maternal plasma and breast-milk selenium concentrations.

DESIGN

HIV-infected Malawian mothers in the Breastfeeding, Antiretrovirals, and Nutrition study were randomly assigned at delivery to receive: LNS, ARV, LNS and ARV, or a control. In a subsample of 526 mothers and their uninfected infants, we measured plasma and breast-milk selenium concentrations at 2 or 6 (depending on the availability of infant samples) and 24 wk postpartum.

RESULTS

Overall, mean (± SD) maternal (range: 81.2 ± 20.4 to 86.2 ± 19.9 μg/L) and infant (55.6 ± 16.3 to 61.0 ± 15.4 μg/L) plasma selenium concentrations increased, whereas breast-milk selenium concentrations declined (14.3 ± 11.5 to 9.8 ± 7.3 μg/L) from 2 or 6 to 24 wk postpartum (all P < 0.001). Compared with the highest baseline selenium tertile, low and middle tertiles were positively associated with a change in maternal plasma or breast-milk selenium from 2 or 6 to 24 wk postpartum (both P < 0.001). With the use of linear regression, we showed that LNS that contained selenium and ARV were not associated with changes in maternal plasma and breast-milk selenium, but maternal selenium concentrations were positively associated with infant plasma selenium at 2 or 6 and 24 wk postpartum (P < 0.001) regardless of the study arm.

CONCLUSIONS

Selenite supplementation of HIV-infected Malawian women was not associated with a change in their plasma or breast-milk selenium concentrations. Future research should examine effects of more readily incorporated forms of selenium (ie, selenomethionine) in HIV-infected breastfeeding women.

Metals and trace element concentrations in breast milk of first time healthy mothers: a biological monitoring study

BACKGROUND

Breast milk is the best source of nutrition for the newborn infant. However, since all infants cannot be breast-fed, there is a need for background data for setting adequate daily intakes. Previously, concentration data on major essential elements and some toxic elements in breast milk, based on different analytical techniques, have been published. There is no recent study on a large number of metals and trace elements in breast milk, using a sensitive analytical method for determination of low element concentrations.

METHODS

Breast milk concentrations of 32 metals and elements in early lactation (days 14-21) were determined in a random sample of first time Swedish mothers (n = 60) using inductively coupled plasma mass spectrometry (ICPMS).

RESULTS

There were small inter-individual concentration variations in the macroelements Ca, K, Mg, P and S, and striking similarities across studies and over time, supporting a tight regulation of these elements in breast milk. Large inter-individual and over time differences were detected for Na concentrations, which may reflect an increase in salt consumption in Swedish women. Large inter-individual differences were also detected for the microelements Co, Cr, Mn and Mo, and the toxic metals As, Cd, Pb, Sb and V. Arsenic and B were positively correlated with fish consumption, indicating influence of maternal intake on breast milk concentrations. Observed differences in breast milk element concentrations across studies and over time could be attributed to the timing of sampling and a general decline over time of lactation (Cu, Fe, Mo, Zn), a possible lack of regulation of certain elements in breast milk (As, B, Co, Mn, Se) and time trends in environmental exposure (Pb), or in some cases to differences in analytical performance (Cr, Fe).

CONCLUSIONS

This study provides reliable updated information on a number of metals and elements in breast milk, of which some have not previously been reported.

Prenatal and Postnatal Epigenetic Programming: Implications for GI, Immune, and Neuronal Function in Autism

Although autism is first and foremost a disorder of the central nervous system, comorbid dysfunction of the gastrointestinal (GI) and immune systems is common, suggesting that all three systems may be affected by common molecular mechanisms. Substantial systemic deficits in the antioxidant glutathione and its precursor, cysteine, have been documented in autism in association with oxidative stress and impaired methylation. DNA and histone methylation provide epigenetic regulation of gene expression during prenatal and postnatal development. Prenatal epigenetic programming (PrEP) can be affected by the maternal metabolic and nutritional environment, whereas postnatal epigenetic programming (PEP) importantly depends upon nutritional support provided through the GI tract. Cysteine absorption from the GI tract is a crucial determinant of antioxidant capacity, and systemic deficits of glutathione and cysteine in autism are likely to reflect impaired cysteine absorption. Excitatory amino acid transporter 3 (EAAT3) provides cysteine uptake for GI epithelial, neuronal, and immune cells, and its activity is decreased during oxidative stress. Based upon these observations, we propose that neurodevelopmental, GI, and immune aspects of autism each reflect manifestations of inadequate antioxidant capacity, secondary to impaired cysteine uptake by the GI tract. Genetic and environmental factors that adversely affect antioxidant capacity can disrupt PrEP and/or PEP, increasing vulnerability to autism.

Blood dynamics of mercury and selenium in northern elephant seals during the lactation period

The effects of reproduction and maternal investment (i.e., milk transfer) on trace element levels remain poorly understood in marine mammals. We examined the blood dynamics of mercury (Hg) and selenium (Se) during lactation in the northern elephant seal (Mirounga angustirostris), a top predator from the North Pacific Ocean. Total Hg and Se levels were measured in whole blood and milk of 10 mother-pup pairs on days 5 and 22 of lactation. Both Hg and Se were transferred to offspring through the milk. Results suggested that the maternal transfer of Se was prominent during lactation, whereas the Hg transfer was larger during gestation. The lactation period affected Hg and Se levels in the blood of elephant seal mothers and pups. Physiological processes and their relationship to body condition should be considered carefully when interpreting trace element levels in the framework of biomonitoring.

Effects of antioxidant supplementation on duodenal Se-Met absorption in ethanol-exposed rat offspring in vivo

The nutritional deficiencies provoked by ethanol consumption, during gestation or lactation, can contribute to multiple birth defects in offspring. In order to improve our knowledge about selenium (Se) distribution in pups exposed to ethanol, the present study evaluated the effect of this drug on intestinal development and determined its action on duodenal absorption of selenomethionine (Se-Met). To determinate if supplementation could improve Se absorption and its serum values, we used two antioxidant supplemented regimens on dams, with selenium alone or selenium plus folic acid, and obtained six groups of pups: C (control), A (alcohol), CS (control + Se), AS (alcohol + Se), CFS (control + Se + folic acid) and AFS (alcohol + Se + folic acid). Duodenal Se-Met transport was performed using an in vivo perfusion method. Se levels were measured by graphite furnace atomic absorption spectrometry. The supplemented diets utilized had a positive influence on body growth, duodenal perimeter and Se content in ethanol-exposed pups. Ethanol exposure increased Se-Met duodenal absorption in all pups, supplemented or not, presenting the highest values of maximal velocity (V(max)) compared with their control counterparts. The affinity constant (K(m)) increased according to rank: A>AS>AFS groups. These results suggest that although antioxidant supplementation does not restore Se-Met absorption to normal values, it enhances the affinity of the transporters for the substrate and improves the damage caused by ethanol in the duodenal mucosa.

Selenium and preeclampsia: A global perspective

Preeclampsia is a complex multisystem disorder of pregnancy where oxidative stress plays an important aetiological role. The role of selenium in the synthesis of endogenous antioxidants is well documented, and a significant reduction in selenium has been reported in preeclamptic women. The objective of this study was to map global selenium status and preeclampsia incidence. This study identified peer reviewed journal articles reporting national preeclampsia incidence (%) and matched these with reported values of selenium intake and plasma/serum selenium concentrations (μg/L). Matched data were obtained for 45 regions, reporting 6456,570 births, spanning Europe, Asia, Australasia, Africa, North and South America. Increasing plasma selenium concentration was found to be correlated with a reduction in preeclampsia incidence (Pearson's r=-0.604, P<0.0001). Countries with a reported serum/plasma selenium level of ⩾95μg/L were considered selenium sufficient and a significant reduction in preeclampsia incidence for countries above this value (P=0.0007) was noted. Significant reductions in preeclampsia incidence were found to coincide with increases in plasma/serum selenium concentration in the New Zealand (P=0.0003) and Finland (0.0028) populations following Government intervention. This study supports the hypothesis that selenium supplementation may be beneficial in reducing oxidative stress in women at risk of preeclampsia.

High concentrations of essential and toxic elements in infant formula and infant foods - A matter of concern

This study assessed concentrations in and intake of toxic and essential elements from formulas and foods intended for infants during their first 6months of life. Concentrations of the essential elements Ca, Fe, Zn, Mn and Mo were significantly higher in most formulas than in breast milk. Daily intake of Mn from formula varies from ten up to several hundred times the intake of the breast fed infant, levels that may be associated with adverse health effects. One portion of infant food provided significantly more Fe, Mn, Mo, As, Cd, Pb and U than one feeding of breast milk, but less Ca, Cu and Se. Rice-based products in particular contained elevated As concentrations. Drinking water used to mix powdered formula may add significantly to the concentrations in the ready-made products. Evaluation of potentially adverse effects of the elevated element concentrations in infant formulas and foods are warranted.

Effect of dietary selenite on development and intestinal absorption in offspring rats

AIM

The present study aims to compare selenium (Se) status in offspring rats born to selenium-deficient and selenium supplemented dams and to analyse Se's influence on intestinal parameters and the intestinal absorption of selenomethionine (Se-Met).

MAIN METHODS

Male and female Wistar rats (150-200 g) were randomised in: control (C) (0.1 ppm Se), Se-deficient (SD) (0.01 ppm Se) and Se-supplemented (SS) (0.5 ppm Se) groups; and were mated to obtain their offspring. Se levels in serum, urine and faeces in offspring and in mothers' milk were measured by graphite-furnace atomic absorption spectrometry. Duodenal transport studies in offspring were performed using an in vivo perfusion of different Se-Met concentrations (2, 5, 10, 25, 75 and 150 μM).

KEY FINDING

A Se-deficient diet provoked a decrease in the offspring's body weight and intestinal parameters, while the supplemented diet increased these values. Serum Se levels were similar between Se-deficient and control offspring because the urinary excretion of Se was smaller to compensate for Se homeostasis. Intestinal Se-Met absorption obeys the Michaelis-Menten equation with lower apparent constant (K(m)) and maximal velocity (V(max)) in the SD group. However, the C and SS groups presented similar K(m) and different V(max). The V(max) showed greater values in the following order of rank: SS>C>SD groups.

SIGNIFICANCE

Selenium intake deficiencies in offspring lead to the development of compensatory mechanisms in order to normalise serum selenium levels. These mechanisms, however, do not permit normal body development; nor do they regulate intestinal parameters and Se-Met transport.

Folic acid and selenite during reproduction, gestation and lactation protect against ethanol changed Se bioavailability

AIMS

Levels of antioxidants such as folic acid and selenium decrease in dams exposed to ethanol during gestation and lactation, affecting their antioxidant status, their reproductive function and consequently the health of their progeny. We will study whether a Se (0.5 p.p.m.) plus folic acid (8 p.p.m.) supplemented diet administered to ethanol-exposed dams and male rats prevents the effects provoked by ethanol in Se bioavailability and in their glutathione peroxidase (GPx) activity, thus improving the health of their offspring.

METHODS

Se levels in tissue were measured by graphite-furnace atomic absorption spectrometry and serum GPx activity by spectrophotometry.

RESULTS

Results show that ethanol decreases Se retention in dams, affecting their tissues' Se deposits, decreasing serum GPx activity, gestational parameters and the weight of their progeny.

CONCLUSIONS

Se plus folic acid balance Se bioavailability, something that is especially important during gestation and lactation, and as a direct result, the health of their progeny is improved.

Ethanol consumption by Wistar rat dams affects selenium bioavailability and antioxidant balance in their progeny

Ethanol consumption affects maternal nutrition, the mothers’ antioxidant balance and the future health of their progeny. Selenium (Se) is a trace element cofactor of the enzyme glutathione peroxidase (GPx). We will study the effect of ethanol on Se bioavailability in dams and in their progeny. We have used three experimental groups of dams: control, chronic ethanol and pair-fed; and three groups of pups. Se levels were measured by graphite-furnace atomic absorption spectrometry. Serum and hepatic GPx activity was determined by spectrometry. We have concluded that ethanol decreased Se retention in dams, affecting their tissue Se deposits and those of their offspring, while also compromising their progeny’s weight and oxidation balance. These effects of ethanol are caused by a reduction in Se intake and a direct alcohol-generated oxidation action.

The selenium levels of mothers and their neonates using hair, breast milk, meconium, and maternal and umbilical cord blood in Van Basin

The objective of the present study is to calculate linear regressions between a mother and her child with respect to their selenium concentration (ng/g) in the following traits: maternal blood and umbilical cord blood, maternal and child hair, maternal milk and child umbilical cord blood, maternal milk and meconium, maternal blood plasma, and child meconium. The data were collected at Research Hospital of the University of Yüzüncü Yil from 30 pairs of mothers and their newborn baby. The mean maternal serum Se level in 30 mothers was 68.52 +/- 3.57 ng/g and cord plasma level was 119.90 +/- 18.08 ng/g. The Se concentration in maternal and neonatal hair was 330.84 +/- 39.03 and 1,124.76 +/- 186.84 ng/g, respectively. The Se concentration of maternal milk at day 14 after delivery was determined as 68.63 +/- 7.78 ng/g (n = 13) and the concentration of Se was 418.90 +/- 45.49 ng/g (n = 22) for meconium of neonatal. There was no significant difference between maternal blood and milk Se levels. However, hair Se concentration was significantly higher than milk and maternal blood Se level. For each trait comparison, the average absolute difference in log(10)-transformed Se concentration was calculated between a mother and her child. The observed average absolute difference was compared with a test distribution of 1,000 resampled bootstrap averages where the number of samples was maintained but the relationship between a mother and her child was randomized among samples (alpha = 0.05).

Effects of selenium status and supplementary seleno-chemical sources on mouse T-cell mitogenesis

Although selenium is thought to be essential for various immune responses, the excess supplementation may have an adverse effect on certain immunological functions. The present study was designed to determine the effective chemical forms of selenium and their optimal levels on T-cell mitogenesis with splenic cells from mice given a selenium-deficient diet for 8 weeks to avoid effects of cellular selenium sources. Although selenium in tissues, except for spleen and thymus, was almost depleted by feeding selenium-deficient diet, the lymphoid organs still contained low levels of selenium. Both activities of cellular glutathione peroxidase (cGPx) and thioredoxin reductase (TR) in liver and splenic cells showed a tendency to decrease by selenium deficiency. However, splenic cells were tolerant against decrease of the selenoenzyme activities, and TR was also more tolerant than cGPx. T-cell proliferation of the selenium-insufficient splenic cells induced by concanavalin A was increased by addition of Na2SeO3, Na2SeO4, Na2Se, seleno-DL-cystine, seleno-L-methionine and selenocystamine. Their promoting action was observed at levels lower than 0.1 micromol/L and was completely suppressed at the highest concentration (1 micromol/L), except for selenocystamine. Na2SeO3 was one of the efficient selenocompounds for the mitogenesis, which was concomitant with the significant induction of cGPx and TR. However, recovery of cGPx activity in the selenium-insufficient cells by supplementary Na2SeO3 was only partial,while TR activity was readily recovered from selenium deficiency. These results therefore indicate that only low levels of selenium is essential for T-cell mitogenesis even in selenium-insufficient splenic cells, and TR, which is readily recovered by Na2SeO3, may be the critical enzyme.