Mean Plasma Selenium Research Articles

Provision of Small-Quantity Lipid-Based Nutrient Supplements Increases Plasma Selenium Concentration in Pregnant Women in Malawi: A Secondary Outcome of a Randomized Controlled Trial

ABSTRACTBackgroundPregnant women in Malawi are at risk of selenium deficiency, which can have adverse effects on pregnancy outcomes. Interventions for improving selenium status are needed.ObjectivesTo assess the effect of provision of small-quantity lipid-based nutrient supplements (SQ-LNSs) to Malawian women during pregnancy on their plasma selenium concentrations at 36 wk of gestation.MethodsPregnant women (≤20 wk of gestation) were randomly assigned to receive daily either: 1) iron and folic acid (IFA); 2) multiple micronutrients (MMN; 130 µg selenium per capsule); or 3) SQ-LNS (130 µg selenium/20 g). Plasma selenium concentrations were measured by inductively coupled plasma mass spectrometry at baseline and after ≥16 wk of intervention (at 36 wk of gestation) and compared by intervention group.ResultsAt 36 wk of gestation, median (quartile 1, quartile 3) plasma selenium concentrations (micromoles per liter) were 0.96 (0.73, 1.23), 0.94 (0.78, 1.18), and 1.01 (0.85, 1.28) in the IFA, MMN, and SQ-LNS groups, respectively. Geometric mean (GM) plasma selenium concentration was 5.4% (95% CI: 1.8%, 9.0%) higher in the SQ-LNS group than in the MMN group and tended to be higher than in the IFA group (+4.2%; 95% CI: 1.0%, 7.8%). The prevalence of adjusted plasma selenium concentrations <1 µmol/L was 55.1%, 57.8%, and 47.3% in the IFA, MMN, and SQ-LNS groups, respectively; it was lower in the SQ-LNS group than in the MMN group, OR = 0.44 (95% CI: 0.24, 0.83), and tended to be lower than in the IFA group, OR = 0.54 (95% CI: 0.29, 1.03). There was a significant interaction between baseline plasma selenium concentration and intervention group (P = 0.003). In the lowest tertile of baseline selenium concentrations, GM plasma selenium concentration was higher, and the prevalence of low values was lower in the SQ-LNS group compared with the MMN and IFA groups at 36 wk of gestation (P ≤ 0.007).ConclusionsProvision of SQ-LNS containing selenium to pregnant women can be an effective strategy for improving their selenium status.This trial was registered at clinicaltrials.gov (identifier: NCT01239693).

Selenium status in a Northern Irish pregnant cohort with iodine deficiency.

Selenium and iodine are trace elements that are maximally concentrated in the thyroid. Iodine is a substrate for thyroid hormone synthesis, while the selenoproteins protect the thyroid from the oxidative stress incurred. We measured plasma selenium concentration in 241 pregnant women in 1st trimester, previously reported to have iodine deficiency. Mean age was 30.3 years (SD 5.4), BMI 26.2 kg/m2 (SD 4.9) and 53% reported taking supplements. Median urinary iodine concentration was 73 μg/L (IQR 37-122) (WHO recommendation, ≥150 μg/L). Mean plasma selenium concentration was 75 µg/L (SD 7.7) which is below the 80-125 µg/L reported to be optimal. Four-day food diaries revealed a selenium intake of 43 µg/day (SD 15.9), also below the 55-70 µg/day reported to be optimal. This is the first report of selenium status in pregnancy on the island of Ireland. The possible combined effects of iodine and selenium deficiencies in pregnancy merit further investigation.

Socio-demographic and lifestyle determinants of the micronutrients status during pregnancy

Abstract Micronutrients status during pregnancy is recognized as one of the environmental factors that can have an impact on maternal and children’s health. The study aims at evaluating sociodemographic, lifestyle, environmental, and pregnancy-related determinants of maternal micronutrients status during pregnancy. The analysis was based on data from the Polish Mother and Child Cohort (REPRO_PL). During the second trimester of pregnancy, 1306 women filled in a modified version of the validated food frequency questionnaire (FFQ) based on which the intake of the following micronutrients was estimated: calcium, magnesium, zinc, copper, selenium, folate, vitamin D, vitamin A and vitamin E. In addition, copper, zinc and selenium levels were measured in the blood collected during the second trimester of pregnancy. About 95% of the women took dietary supplements during pregnancy. Despite such supplementation in the case of a high proportion of the women the intake of majority of the analyzed micronutrients was below recommendations for the pregnancy period (based on the Estimated Average Requirement). The mean plasma zinc, copper and selenium concentrations were 0.9±0.3 mg/l, 2.0±0.6 mg/l and 48.4±10.5 ug/l, respectively. The chance to reach the recommended intake for vitamin A, vitamin D and selenium was higher among the multiparous women (OR = 1.53 p = 0.007; OR = 1.44 p = 0.02; OR = 1.48 p = 0.009) and for zinc among the women with a higher socio-economic status (SES) (OR = 1.43 p = 0.04). For other variables the results were not statistically significant. A higher selenium level in the plasma was observed among the older women (p = 0.01) and those with a higher SES (p = 0.03). The current study presents evidence on specific factors influencing the micronutrients intake. They need to be accounted for in educational programs and interventions that focus on healthy diet recommendations during pregnancy. Key messages In the case of a high proportion of the women the intake of majority of the analyzed micronutrients was below recommendations for the pregnancy period. More effort should be taken to educational programs and interventions that focus on healthy diet recommendations during pregnancy.

Selenium status and fungi in the protein-losing enteropathy of persistent diarrhea.

A vicious cycle of infection, malabsorption, and malnutrition has been implicated in the perpetuation of diarrheal disease. This study examined whether persistent diarrhea is associated with changes in selenium status and stool alpha-1 antitrypsin (AAT) concentration. This cross-sectional study included 30 children aged 1-12 years with persistent diarrhea who were hospitalized in Cipto Mangunkusumo Hospital and Fatmawati Hospital, Jakarta, and 30 apparently healthy children who were matched by age and sex and lived in a rural area of Jakarta. Clinical examinations, blood routine tests, erythrocyte glutathione peroxidase (GPX) activity and plasma selenium levels as well as AAT in fresh stool samples were performed in all the subjects. Of 30 children with persistent diarrhea, 17 had moderate malnutrition and 13 had severe malnutrition. The mean plasma selenium was significantly lower in children with persistent diarrhea than in children without diarrhea (86.0 μg/L [95% CI: 76.1-95.9] vs 110 μg/L [95% CI: 104-116, p<0.0001). The mean stool AAT concentration was significantly higher in children with persistent diarrhea than in those without diarrhea (115 mg/dL [95% CI: 38.5-191] vs 16 mg/dL [95% CI: 4.0-13.5, p<0.0001]). Selenium correlated with AAT (p=0.05). Fecal fungi were persistently present. Although selenium status in both groups was optimal for the obtained plasma GPX activity, children with persistent diarrhea exhibited lower plasma selenium levels. This study suggests that the decrease in the plasma selenium level may be the consequence of protein loss and that fungi may be involved.

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Plasma albumin, selenium, chromium and manganese levels of thirty patients each with HIV/AIDS, diabetes mellitus and cardiovascular disease (CVD), and one hundred and six apparently healthy adults in Akwa-Ibom and Cross River States, South-South Nigeria was studied. The mean plasma albumin was higher in the control than in the disease patients. The mean plasma selenium was lowest in the control (0.004 ± 0.01 mg/L) than in the HIV/AIDS (0.007 ± 0.00 mg/L), diabetes mellitus (0.007 ± 0.00 mg/L) and CVD (0.010 ± 0.00 mg/L) patients. The mean plasma chromium was highest in the HIV/AIDS patients (0.125 ± 0.45 mg/L) and lowest in the diabetes mellitus patients (0.106 ± 0.04 mg/L). Plasma manganese level was highest in the control (0.028 ± 0.02 mg/L). Manganese was detected in the plasma of all the diseased patients. For the total healthy subjects, only 55.67, 68.87 and 83.93% had selenium, chromium and manganese detected in their blood plasma. There was no significant correlation between plasma levels of albumin, selenium, chromium and manganese (P > 0.05) in the control. The poor nutritional status of the disease patients was reflected by the depressed albumin levels. Key words: Health, disease, trace elements, plasma levels.

Comparative study of plasma zinc and selenium levels amongst Human Immunodeficiency Virus(HIV) positive and negative subjects

The study was a comparative evaluation of plasma levels of selenium and zinc trace elements amongst HIV-positive and HIV-negative apparently healthy, individuals. The comparative cross sectional study comprised two groups of forty HIV positive and HIV negative subjects respectively who were gotten by consecutive clinic recruitment and random sampling respectively. A structured questionnaire was used to retrieve the sociodemographic data after obtaining informed consent from willing participants. Blood samples were collected aseptically into ethylenediaminetetraacetic acid (EDTA) vacutainer bottles and later analyzed by atomic absorption spectrophotometry (AAS). Data analyses were carried out using data analysis software EpiInfo 7 and Microsoft Word Excel 2007. Results were presented as mean ± standard deviation and the student t- test was used to compare means with significance set at P≤0.05. Findings included, instructively, a mean plasma selenium (μg/dl) of 0.0052 ± 0.0024 and 0.0223 ± 0.0054 among HIV negative and positive subjects respectively (p <0.00001). This was in contradistinction to plasma zinc levels where in mean plasma levels(μg/dl) were 122.620 ± 8.571 and 83.35 ± 5.49 for HIV negative and positive subjectsrespectively (p < 0.00001). This may be a pointer to the need for supplementation of certain micronutrients during treatment of HIV infection, as had been noted in some other studies.

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&nbsp; The soil contents of trace elements selenium, chromium and manganese were measured to determine&nbsp; their impact on the plasma levels of 160 healthy adult Nigerians in five different experimental locations&nbsp; in Cross River and Akwa Ibom States, South - South Nigeria. The mean (&plusmn;SD) soil selenium, chromium&nbsp; and manganese concentrations were 2.86 &plusmn; 3.97, 15.93 &plusmn; 3.35 and 90.33&plusmn; 42.65 mg/kg, respectively.&nbsp; Manganese soil concentration was the highest and selenium soil concentration was the lowest in all the&nbsp; locations. The mean (&plusmn;SD) plasma selenium, chromium and manganese concentrations were 0.006,&nbsp; 0.111 &plusmn; 0.031 and 0.028 &plusmn; 0.024 mg /1, respectively. There were no significant differences between the&nbsp; concentrations of the trace elements in the soil and the plasma levels as determined by t-test. Plasma&nbsp; levels of chromium and manganese according to the study were adequate but that of selenium was low.&nbsp; &nbsp; Key words: Healthy adult Nigerians, trace elements, plasma level, soil content.

Plasma selenium status in a group of Australian blood donors and fresh blood components

The purpose of this study was to assess plasma selenium levels in an Australian blood donor population and measure extra-cellular selenium levels in fresh manufactured blood components. Selenium levels were measured using graphite furnace atomic absorption spectrometry with Zeeman background correction. The mean plasma selenium level in healthy plasmapharesis donors was 85.6±0.5μg/L and a regional difference was observed between donors in South East Queensland and Far North Queensland. Although participants had selenium levels within the normal range (55.3–110.5μg/L), 88.5% had levels below 100μg/L, a level that has been associated with sub-optimal activity of the antioxidant enzyme glutathione peroxidase (GPx). Extra-cellular selenium levels in clinical fresh frozen plasma (cFFP) and apheresis-derived platelets (APH Plt) were within the normal range. Packed red blood cells (PRBC) and pooled buffy coat-derived platelets (BC Plt) had levels at the lower limit of detection, which may have clinical implications to the massively transfused patient.

DEFICIENCIA DE SELENIO EN UNA POBLACIÓN ADULTA SANA ESPAÑOLA

Introduction: Selenium is an essential micronutrient for human health, being a cofactor for enzymes with antioxidant activity that protect the organism from oxidative damage. An inadequate intake of this mineral has been associated with the onset and progression of chronic diseases such as hypertension, diabetes, coronary diseases, asthma, and cancer. For this reason, knowledge of the plasma and erythrocyte selenium levels of a population makes a relevant contribution to assessment of its nutritional status. Objetive: The objective of the present study was to determine the nutritional status of selenium and risk of seleniumdeficiency in a healthy adult population in Spain by examining food and nutrient intake and analyzing biochemical parameters related to selenium metabolism, including plasma and erythrocyte levels and selenium-dependent glutathione peroxidase (GPx) enzymatic activity. Material and methods: We studied 84 healthy adults (31 males and 53 females) from the province of Granada, determining their plasma and erythrocyte selenium concentrations and the association of these levels with the enzymatic activity of glutathione peroxidase (GPx) and with life style factors. We also gathered data on their food and nutrient intake and the results of biochemical analyses. Correlations were studied among all of these variables. Results: The mean plasma selenium concentration was 76.6 ± 17.3 μg/L (87.3 ± 17.4 μg/L in males, 67.3 ± 10.7 μg/L in females), whereas the mean erythrocyte selenium concentration was 104.6 μg/L (107.9 ± 26.1 μg/L in males and 101.7 ± 21.7 μg/L in females). The nutritional status of selenium was defined by the plasma concentration required to reach maximum GPx activity, establishing 90 μg/L as reference value. According to this criterion, 50% of the men and 53% of the women were selenium deficient. Conclusions: Selenium is subjected to multiple regulation mechanisms. Erythrocyte selenium is a good marker of longerterm selenium status, while plasma selenium appears to be a marker of short-term nutritional status. The present findings indicate a positive correlation between plasma selenium concentration and the practice of physical activity. Bioavailability studies are required to establish appropriate reference levels of this mineral for the Spanish population.

Deficient selenium status of a healthy adult Spanish population.

Selenium is an essential micronutrient for human health, being a cofactor for enzymes with antioxidant activity that protect the organism from oxidative damage. An inadequate intake of this mineral has been associated with the onset and progression of chronic diseases such as hypertension, diabetes, coronary diseases, asthma, and cancer. For this reason, knowledge of the plasma and erythrocyte selenium levels of a population makes a relevant contribution to assessment of its nutritional status. The objective of the present study was to determine the nutritional status of selenium and risk of selenium deficiency in a healthy adult population in Spain by examining food and nutrient intake and analyzing biochemical parameters related to selenium metabolism, including plasma and erythrocyte levels and selenium-dependent glutathione peroxidase (GPx) enzymatic activity. We studied 84 healthy adults (31 males and 53 females) from the province of Granada, determining their plasma and erythrocyte selenium concentrations and the association of these levels with the enzymatic activity of glutathione peroxidase (GPx) and with life style factors. We also gathered data on their food and nutrient intake and the results of biochemical analyses. Correlations were studied among all of these variables. The mean plasma selenium concentration was 76.6 ± 17.3 μg/L (87.3 ± 17.4 μg/L in males, 67.3 ± 10.7 μg/L in females), whereas the mean erythrocyte selenium concentration was 104.6 μg/L (107.9 ± 26.1 μg/L in males and 101.7 ± 21.7 μg/L in females). The nutritional status of selenium was defined by the plasma concentration required to reach maximum GPx activity, establishing 90 μg/L as reference value. According to this criterion, 50% of the men and 53% of the women were selenium deficient. Selenium is subjected to multiple regulation mechanisms. Erythrocyte selenium is a good marker of longer term selenium status, while plasma selenium appears to be a marker of short-term nutritional status. The present findings indicate a positive correlation between plasma selenium concentration and the practice of physical activity. Bioavailability studies are required to establish appropriate reference levels of this mineral for the Spanish population.

Plasma selenium concentrations in pregnant women in two countries with contrasting soil selenium levels

Project Selenium has an important role in antioxidant defense and cell mediated immunity. Plasma selenium is a useful biomarker for comparing selenium status across populations, and influenced by selenium levels of soils and plants. Procedure This cross-sectional study compared plasma selenium (by electrothermal atomic absorption spectrophotometry) of women at 24 weeks gestation in Malawi ( n = 152) and the Philippines ( n = 301), countries with low and high soil selenium levels, respectively. Data on anthropometry, smoking, intakes of energy, nutrients and food groups (via 24-h recalls), hemoglobin, serum zinc, and C-reactive protein (CRP) were also collected. Results Mean (95% CI) plasma selenium was lower for Malawian than Filipino women (0.79, 0.77, 0.82 μmol/L vs. 1.44, 1.41, 1.47 μmol/L; p < 0.001); 83% had concentrations below 1.0 μmol/L compared to 3% in the Filipinos. Cereals provided 78% and 67% of the energy in Malawi and the Philippines, respectively compared to 4% and 8.5%, respectively for cellular animal protein. Plasma selenium was correlated modestly with BMI ( r = −0.138; p = 0.096) and elevated CRP (>5.0 mg/L) ( r = −0.143; p = 0.084) in Malawi, and significantly with intake of cellular animal protein (g/d) ( r = 0.23; p = 0.020) and serum zinc ( r = 0.13; p = 0.044) in the Philippines. No comparable relationships were observed in either group for smoking, hemoglobin, or cereal intakes. Conclusion Differences in plasma selenium paralleled reported trends in selenium concentrations in soils and staple cereals in Malawi and the Philippines. The biological significance of the lower plasma selenium for the Malawian women, and the extent to which they pose a risk for fetal and neonatal development, is uncertain.

The effect of the classical and medium chain triglyceride ketogenic diet on vitamin and mineral levels

The risk of nutritional deficiency in children on restrictive dietary treatments and a lack of ketogenic diet (KD)-specific UK supplements raises concerns about micronutrient status. Vitamin A, E, zinc, selenium and magnesium levels were therefore examined in children with intractable epilepsy treated with the KD. Plasma vitamins A and E, zinc, selenium and magnesium levels were measured at baseline and after 3, 6 and 12months on the classical (n=46) or medium chain triglyceride (MCT) (n=45) KD in children aged 2-16years, as part of a randomised trial, and pairwise comparisons with baseline were performed. Data were available from 91 children. From baseline to 12months, mean plasma vitamin A decreased from 1.41μmol L(-1) to 1.13μmol L(-1) in the classical group (P<0.001) but increased from 1.52μmol L(-1) to 1.81μmol L(-1) in the MCT group (P<0.001). Mean plasma vitamin E increased from 22.7μmol L(-1) to 33.2μmol L(-1) in the classical group (P<0.001) and from 22.3 μmol L(-1) to 23.3μmol L(-1) in the MCT group (P<0.05). No significant change in plasma zinc was seen at 12months, although mean plasma selenium decreased from 0.95μmol L(-1) to 0.88μmol L(-1) in the group as a whole (P<0.05). Mean plasma magnesium decreased from 0.87mmol L(-1) to 0.83mmol L(-1) in the group as a whole (P<0.001); when subdivided by KD type, this was limited to the classical group. Changes in plasma vitamins A and E and the decline in magnesium status after 12months of KD treatment suggest that micronutrient status may be suboptimal in this group and that available formulations for KD supplementation may need reviewing.

Effect of Supplementation With High-Selenium Yeast on Plasma Lipids

High selenium status has been linked to elevated blood cholesterol levels in cross-sectional studies. To investigate the effect of selenium supplementation on plasma lipids. Randomized, placebo-controlled, parallel-group study stratified by age and sex. Participants, research nurses, and persons assessing outcomes were blinded to treatment assignment. (International Standard Randomised Controlled Trial Number Register registration number: ISRCTN25193534) 4 general practices in the United Kingdom. 501 volunteers aged 60 to 74 years. Participants received selenium, 100 mcg/d (n = 127), 200 mcg/d (n = 127), or 300 mcg/d (n = 126), as high-selenium yeast or a yeast-based placebo (n = 121) for 6 months. Total and high-density lipoprotein (HDL) cholesterol concentrations were measured in nonfasting plasma samples stored from participants in the UK PRECISE (United Kingdom PREvention of Cancer by Intervention with SElenium) Pilot Study at baseline (n = 454) and at 6 months (n = 394). Non-HDL cholesterol levels were calculated. Mean plasma selenium concentration was 88.8 ng/g (SD, 19.2) at baseline and increased statistically significantly in the treatment groups. The adjusted difference in change in total cholesterol levels for selenium compared with placebo was -0.22 mmol/L (-8.5 mg/dL) (95% CI, -0.42 to -0.03 mmol/L [-16.2 to -1.2 mg/dL]; P = 0.02) for 100 mcg of selenium per day, -0.25 mmol/L (-9.7 mg/dL) (CI, -0.44 to -0.07 mmol/L [-17.0 to -2.7 mg/dL]; P = 0.008) for 200 mcg of selenium per day, and -0.07 mmol/L (-2.7 mg/dL) (CI, -0.26 to 0.12 mmol/L [-10.1 to 4.6 mg/dL]; P = 0.46) for 300 mcg of selenium per day. Similar reductions were observed for non-HDL cholesterol levels. There was no apparent difference in change in HDL cholesterol levels with 100 and 200 mcg of selenium per day, but the difference was an adjusted 0.06 mmol/L (2.3 mg/dL) (CI, 0.00 to 0.11 mmol/L [0.0 to 4.3 mg/dL]; P = 0.045) with 300 mcg of selenium per day. The total-HDL cholesterol ratio decreased progressively with increasing selenium dose (overall P = 0.01). The duration of supplementation was limited, as was the age range of the participants. Selenium supplementation seemed to have modestly beneficial effects on plasma lipid levels in this sample of persons with relatively low selenium status. The clinical significance of the findings is unclear and should not be used to justify the use of selenium supplementation as additional or alternative therapy for dyslipidemia. This is particularly true for persons with higher selenium status, given the limitations of the trial and the potential additional risk in other metabolic dimensions. The Cancer Research Campaign (now Cancer Research UK) and the University of Surrey.

Health and Nutritional Status of Wild Australian Psittacine Birds: An Evaluation of Plasma and Hepatic Mineral Levels, Plasma Biochemical Values, and Fecal Microflora

To evaluate the health and nutritional status of 3 wild Australian psittacine species, plasma and hepatic mineral concentrations and plasma biochemical values were measured in wild-caught galahs (Eolophus roseicapilla), long-billed corellas (Cacatua tenuirostris), and sulphur-crested cockatoos (Cacatua galerita). No correlations were found between hepatic and plasma mineral levels. Mean plasma calcium (1.79 mmol/L [7.16 mg/dL]) and sodium (103 mmol/ L [103 mEq/L]) concentrations were lower, whereas mean total phosphorus (6.53 mmol/L [20.22 mg/dL]) and potassium (8.87 mmol/L [8.87 mEq/L]) concentrations were higher than values for captive counterparts. Plasma iron levels were higher than those reported for captive counterparts, with evidence of interspecific (sulphur-crested cockatoos, 109 micromol/L [609 microg/dL]; corellas, 57 micromol/L [318 microg/dL]; galahs, 90 micromol/L [503 microg/dL]) and temporal variation (galahs: May, 107 micromol/L [598 microg/dL]; July, 59 micromol/L [330 microg/dL]). Hepatic iron concentrations were as high as 1030 mg/kg. Interspecific variation was minimal in mean plasma selenium (11.8 micromol/L [929 microg/L]) and zinc (31.2 micromol/L [204 microg/dL]) concentrations. Plasma biochemical values varied significantly from reported reference ranges. Ranges for total protein, albumin, and bile acid concentrations were lower, whereas uric acid, glutamate dehydrogenase, amylase, and cholesterol concentrations were higher than those previously reported for these species, and interspecific variation was evident. Variation in measures of mineral status or plasma biochemical values between males and females were negligible. An evaluation of fecal microflora showed a distinct absence of gram-negative bacteria or budding yeast. Results of this study show that analyte values used to determine health and nutritional status of wild birds differ from those published for captive counterparts. Although analyte values appear to vary minimally by sex, distinct taxonomic and some temporal differences exist in values from wild birds of these 3 species.

Higher Selenium Status is Associated with Adverse Blood Lipid Profile in British Adults1–3

Recent findings have raised concern about possible associations of high selenium exposure with diabetes and hyperlipidemia in the US, a population with high selenium status. In the UK, a population with lower selenium status, there is little data on the association of selenium status with cardio-metabolic risk factors in the general population. We examined the association of plasma selenium concentration with blood lipids in a nationally representative sample of British adults. A cross-sectional study was conducted among 1042 white participants (aged 19–64 y) in the 2000–2001 UK National Diet and Nutrition Survey. Plasma selenium was measured by inductively coupled-plasma mass spectrometry. Total and HDL cholesterol were measured in nonfasting plasma samples. Mean plasma selenium concentration was 1.10 ± 0.19 μmol/L. The multivariate adjusted differences between the highest (≥1.20 μmol/L) and lowest (<0.98 μmol/L) quartiles of plasma selenium were 0.39 (95% CI 0.18, 0.60) mmol/L for total cholesterol, 0.38 (0.17, 0.59) for non-HDL cholesterol, and 0.01 (−0.05, 0.07) for HDL cholesterol. Higher plasma selenium (i.e., ≥1.20 μmol/L) was associated with increased total and non-HDL cholesterol levels but not with HDL in the UK adult population. These findings raise additional concern about potential adverse cardio-metabolic effects of high selenium status. Randomized and mechanistic evidence is necessary to assess causality and to evaluate the impact of this association on cardiovascular risk.

Effects of selenomethionine supplementation on selenium status and thyroid hormone concentrations in healthy adults

Background: Selenium, a potential cancer prevention agent currently being tested against prostate cancer in the Selenium and Vitamin E Cancer Prevention Trial (SELECT), plays an integral role in thyroid metabolism. The effects of long-term selenium supplementation on thyroid hormone concentrations are unknown.Objective: The objective was to investigate the effects of long-term selenium supplementation on thyroid hormone concentrations.Design: Twenty-eight healthy adults took 200 μg selenomethionine/d for 28 mo. The thyroid hormones triiodothyronine (T3), thyroxine (T4), and thyrotropin (TSH) were measured in plasma for 4 mo before supplementation and quarterly during supplementation. The assay methods were changed midstudy; the results of the 2 methods were not comparable. Therefore, one analysis was conducted based on the results of the first method, and a second analysis was based on all of the data, adjusted for the change. Serial data collection permitted a test for trends rather than simply a difference between initial and final values.Results: By 9 mo, mean (±SEM) plasma selenium concentrations had increased from 1.78 ± 0.07 μmol/L at baseline to 2.85 ± 0.11 μmol/L for men and from 1.64 ± 0.04 to 3.32 ± 0.1.2 μmol/L for women. T3 concentrations in men increased 5% per year (P = 0.01). T4 and TSH concentrations were unchanged.Conclusions: Selenium supplementation produced no clinically significant changes in thyroid hormone concentrations. A small but statistically significant increase in T3 concentrations was noted in men, with no corresponding decreases in TSH. A subset of SELECT subjects might be monitored periodically for changes during long-term selenium supplementation.

Interaction between Single Nucleotide Polymorphisms in Selenoprotein P and Mitochondrial Superoxide Dismutase Determines Prostate Cancer Risk

Selenium may affect prostate cancer risk via its plasma carrier selenoprotein P which shows dramatically reduced expression in prostate cancer tumors and cell lines. The selenoprotein P (SEPP1) Ala234 single nucleotide polymorphism (SNP) allele is associated with lower plasma selenoprotein P in men, reducing the concentration/activity of other antioxidant selenoproteins. Selenium status also modifies the effect of the mitochondrial superoxide dismutase (SOD2) SNP Ala16Val on prostate cancer risk. We investigated the relationship of these SNPs with prostate cancer risk. DNA from 2,975 cases and 1,896 age-matched controls from the population-based Prostate Cancer in Sweden study were genotyped using TaqMan assays. Cases were designated aggressive or nonaggressive prostate cancers at diagnosis by clinical criteria. Association with prostate cancer was investigated by logistic regression; gene-gene interaction using a general linear model. The mean plasma selenium concentration measured in 169 controls was relatively low (76.0 +/- 17.2 microg/L). SNP genotype distributions were in Hardy-Weinberg equilibrium. SOD2-Ala16+ men were at a greater risk of prostate cancer [odds ratios (OR), 1.19; 95% confidence intervals (CI), 1.03-1.37] compared with SOD2-Val16 homozygotes. Men homozygous for SEPP1-Ala234 who were also SOD2-Ala16+ had a higher risk of prostate cancer (OR, 1.43; 95% CI, 1.17-1.76) and aggressive prostate cancer (OR, 1.60; 95% CI, 1.22-2.09) than those who were SOD2-Val16 homozygotes (interaction, prostate cancer P = 0.05; aggressive prostate cancer P = 0.01). This interaction was stronger in ever-smokers: SOD2-Ala16+ men homozygous for SEPP1-Ala234 had an almost doubled risk of prostate cancer (OR, 1.97; 95% CI, 1.33-2.91; interaction P = 0.001). In a low-selenium population, SOD2-Ala16+ men homozygous for SEPP1-Ala234 are at an increased risk of prostate cancer/aggressive prostate cancer especially if ever-smokers, because they are likely to produce more mitochondrial H(2)O(2) that they cannot remove, thereby promoting prostate tumor cell proliferation and migration.

A case‐control study of the relation between plasma selenium and asthma in European populations: a GA2LEN project*

There is evidence that selenium levels are relatively low in Europe and may be falling. Low levels of selenium or low activity of some of the enzymes dependent on selenium have been associated with asthma. The GA(2)LEN network has organized a multicentre case-control study in Europe to assess the relation of plasma selenium to asthma. The network compared 569 cases in 14 European centres with a diagnosis of asthma and reporting asthma symptoms in the last 12 months with 576 controls from the same centres with no diagnosis of asthma and no asthmatic symptoms in the last 12 months. All cases and controls were selected from the same population defined by age and place of residence. Mean plasma selenium concentrations among the controls ranged from 116.3 microg/l in Palermo to 67.7 microg/l in Vienna and 56.1 microg/l among the children in Oslo. Random effects meta-analysis of the results from the centres showed no overall association between asthma and plasma selenium [odds ratio (OR)/10 microg/l increase in plasma selenium: 1.04; 95% confidence interval (CI): 0.89-1.21] though there was a significantly protective effect in Lodz (OR: 0.48; 95% CI: 0.29-0.78) and a marginally significant adverse effect in Amsterdam (OR: 1.68; 95% CI: 0.98-2.90) and Ghent (OR: 1.35; 95% CI: 1.03-1.77). This study does not support a role for selenium in protection against asthma, but effect modification and confounding cannot be ruled out.

Low plasma selenium concentrations and mortality among older community-dwelling adults: the InCHIANTI Study

We examined the relationship between plasma selenium levels at enrollment and all-cause mortality over a 6-year period among participants in the InCHIANTI study. 1042 men and women > or =65 years from the InCHIANTI study, a population- based study of older adults living in the Chianti region of Tuscany, a population-based cohort in Tuscany, Italy. Plasma selenium was measured at enrollment (1998-2000), and vital status was ascertained until May 2006. During follow-up, 237 participants (22.7%) died. At enrollment, mean (SD) plasma selenium concentrations among participants who survived or died were 0.96 (0.14) and 0.87 (0.18) micromol/L (p<0.0001), respectively. The proportion of participants who died, from lowest to highest quartile of selenium, was 41.3, 27.0, 18.1 and 13.5% (p<0.0001 by Mantel-Haenszel chi-square). After adjusting for age, sex, education, and chronic diseases, adults in the lowest quartile of plasma selenium at enrollment had higher mortality compared with those in the highest quartile (Hazard Ratio (HR) 1.60, 95% Confidence Interval (CI) 1.04-2.47, p=0.034). Low plasma selenium may be an independent predictor of mortality among older adults living in the community.

Plasma selenium levels in healthy blood bank donors in the central-eastern part of Belgium

Graphite furnace atomic absorption spectrometry, with Zeeman background correction and after improved matrix modification, was used to measure the plasma selenium content of healthy blood bank donors in the central part of Belgium. The mean plasma selenium concentration of 80 men and 80 women was 79.7±4.4 ng/mL with a range of 55.0–117.4 ng/mL. There was no gender difference observed. Plasma selenium level was significantly highest for the adult group, aged 45–64 years, compared to the others, except the young adults (18–24 years). The mean plasma selenium concentration measured corresponded well with literature data for Belgium. The obtained values were found to be in the medium range, compared with recent literature values for the European countries.