The selenium status of Belgian population groups : I. Healthy adults

Selenium status parameters in patients with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age. To date, no systematic study of interactions between selenium status parameters (SSPs: serum selenium concentration, plasma glutathione peroxidase, GPX3, plasma selenoprotein P, SELENOP), sex hormones, thyroid function parameters, and other laboratory parameters in patients with PCOS has been undertaken. Therefore we aimed to compare such parameters in women with PCOS and in the control groups, and to investigate the multidimensional interactions between various parameters in PCOS patients and in controls. The subjects were diagnosed either with PCOS (n=28, 25.4±5.2 y) or with PCOS+Hashimoto disease (n=13, 27.3±5.6 y). Female patients having normal menses were recruited into the first control group (n=70, 26.8±7.3 y) or to the second control group comprising women only with Hashimoto disease (n=10, 26.2±6.9 y). No apparent differences in SSPs between control subjects and patients with PCOS, also complicated with Hashimoto disease, were identified, though such differences were noticeable for total testosterone (tT), sex hormone binding globulin, free androgen index, dehydroepiandrosterone sulfate (DHEAS), and insulin profile. The correlation between tT and DHEAS was found the strongest. The other group of mutually highly and positively correlated parameters consisted of GPX3, follicle stimulating hormone, free triiodothyronine and free thyroxine. All the latter parameters correlated negatively with vitamin D3. SSPs took part in interactions with thyroid hormones, sex hormones and some other parameters, but only for GPX3 such interactions were statistically significant. The significance of these findings remains open for further investigation, particularly in patients with PCOS and/or Hashimoto disease.

Interference of gadolinium on the measurement of selenium in human serum by inductively coupled plasma-quadrupole mass spectrometry

Selenium is an important clinical biomarker of nutritional status; however, the occurrence of gadolinium in a patient's serum as a result of the contrast agents used during magnetic resonance imaging investigations, results in a significant positive bias in its measurement by inductively coupled plasma-quadrupole mass spectrometry.

Selenium status of the Swiss population: assessment and change over a decade

A monitoring study of serum selenium concentration was carried out on healthy blood donors from different regions of Switzerland. With an overall mean serum concentration of 98 microg/L (n=1847), the selenium status of the healthy adults can be assessed as adequate. The lowest measured concentration of 62 microg/L denotes that the risk of a marginal selenium deficiency in the Swiss population is small. Compared to a similar study carried out in 1993, the status improved for both genders, although the increase is higher among women. It is noteworthy that the supplementation practice has increased during this period with ca. 2% of the population taking Se-micronutrients. No correlation between the age and the serum concentration is detected, even though the age-range was enlarged in this study to 18-68 years for the women and to 19-72 years for the men. The place of residence only marginally influences the selenium concentration, which implies a certain uniformity of the dietary habits between the various regions of the country.

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+/-4.4ng/mL with a range of 55.0-117.4ng/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.

Relationships between selenium, lipids, iron status and hormonal therapy in women of the SU.VI.M.AX cohort

Significant differences in serum selenium concentration according to contraceptive treatment and age have been evidenced in women of the SU.VI.M.AX cohort. This study aimed at verifying the physiopathological hypothesis that the observed increase in serum selenium concentration could be related to serum lipid increase and/or bleeding decrease. Women were divided into six groups: menopausal with or without hormonal replacement therapy; non-menopausal using contraceptive pills; intrauterine device; other contraceptive treatment or no contraceptive treatment. Adjusted linear regression indicated positive associations between selenium and apolipoprotein A1 (r(2) from 0.038 to 0.074, p<0.07 depending on groups) or ferritin in serum (r(2) from 0.032 to 0.075, p<0.07 depending on groups). These relationships could explain the differences observed according to hormonal treatment and age in the SU.VI.MAX study.

Serum selenium determinants in French adults: the SU.VI.M.AX study

The objective of the present work was to assess the relationship between serum Se concentrations and environmental determinants (i.e. lifestyle, social activity, geographic region, urban status, education, familial status, physical activity, BMI, tobacco, and food and alcohol consumption). Baseline results from 13 017 subjects (7876 women aged 35-60 and 5141 men aged 45-60) who participated in the SU.VI.M.AX (Supplémentation en Vitamines et Minéraux Antioxydants) study were analysed. Fewer than 2 % of the volunteers had a serum Se status under 0.75 micromol/l, which has been quoted as the cut-off of biological Se sub-deficiency. Women had significantly lower serum Se concentrations than men (1.09 (sd 0.19) micromol/l (n 7423) and 1.14 (sd 0.20) micromol/l (n 4915), P<0.0001, respectively). Significant differences in serum Se concentrations were observed between geographic areas. In both sexes, the serum Se concentration increased with alcohol, meat and fish consumption, and decreased with smoking. In premenopausal women, the serum Se concentration was higher in contraceptive-pill users than in non-users. In women only, age was associated with increased serum Se concentrations, and obesity (BMI> or =30 kg/m2) was associated with decreased serum Se levels. In men, we observed a decrease in serum Se concentrations with increased consumption of vegetables and fruits. In conclusion, though few of the volunteers participating in the SU.VI.M.AX study had Se status in the sub-deficiency range, 83 % of women and 75 % of men had serum concentrations below the value considered optimal for glutathione peroxidase activity. The largest Se associations in both sexes were found with regions, smoking, alcohol, meat and fish consumption. Further studies are needed to understand the difference in Se status between genders.

Serum selenium is associated with plasma homocysteine concentrations in elderly humans

Low selenium levels in humans have been associated with several pathologies; however, an earlier animal investigation found a direct association between Se intake and total plasma homocysteine (tHcy) concentrations. To date, the importance of serum selenium levels in association with tHcy in humans has not been determined. We evaluated the cross-sectional association of blood selenium concentrations with plasma tHcy and other determinants of this cardiovascular disease risk factor. We estimated protein intake and measured the blood status of selenium, tHcy, and several other related factors in serum such as folate, vitamin B-12, and creatinine. Serum selenium was inversely associated with tHcy, explaining 5.8% of tHcy variance with respect to 2.2% accounted for by serum folate. Furthermore, there was a 63% decreased risk of higher tHcy concentrations (>14 micro mol/L) for subjects with serum selenium in the highest tertile (P = 0.013). We also found an inverse association of protein intake with tHcy in men (beta = -0.144; P = 0.036), which disappeared after controlling for serum Se concentrations (beta = -0.055; P = 0.003). In conclusion, selenium should be considered as a potential factor to lower tHcy. In addition, the described association between protein intake and homocysteine levels could be mediated by this trace element.

Comparison of the serum selenium content of healthy adults living in the Antwerp region (Belgium) with recent literature data

Graphite furnace atomic absorption spectrometry, after improved matrix modification and using Zeeman background correction, was used to measure the serum selenium content of healthy adults living in the Antwerp region (Belgium). The mean serum concentration of 13 men and 13 women, sampled once a month during 1 year, was 84.3 +/- 9.4ng/ml with a broad range of 51.4-121.7 ng/ml. The intra-individual variation was remarkably high. Recent literature on selenium concentrations is reviewed and values are tabulated, with limitation to healthy adults and European countries. The mean serum selenium concentration measured corresponded well to older literature data for Belgium. The obtained values were found to be in the medium range compared with the literature data for other European countries.

Selenium status of low-selenium area residents: Polish experience

The concentration of selenium (Se) in human organism varies widely between geographical areas depending on its content in soil and plants, dietary Se intake, bioavailability and retention, mineral interactions and other factors. The study includes healthy inhabitants of different regions of Poland; pregnant women, lactating women, children from 0 to 15 years of age and adults. Systematic determinations allow us to observe changes of the concentration of Se in time, which may be significant for developing preventive action. The results obtained confirm our thesis that Se concentration in the blood of the inhabitants of Poland depends on the region of the country. In recent years, in a considerable number of Polish inhabitants, the concentration of Se in blood plasma has been relatively low-about 50-55 microg/l, and the calculated daily dietary intake about 30-40 microg/day. The low levels of the element in the blood and urine are probably due to its deficiency in the diet.

Selenium and breast-feeding

The objective of the present review is to discuss Se nutrition during breast-feeding, encompassing environmental and maternal constitutional factors affecting breast-milk-Se metabolism and secretion. A literature search of Medline and Webofscience was used to retrieve and select papers dealing with Se and breast milk. Although Se in natural foods occurs only in organic form, breast milk responds to organic and inorganic Se in supplements. Inorganic Se (selenite, selenate), which is largely used in maternal supplements, is not detectable in breast milk. The mammary-gland regulating mechanism controls the synthesis and secretion of seleno-compounds throughout lactation, with a high total Se level in colostrum that decreases as lactation progresses. Se appears in breast milk as a component of specific seleno-proteins and seleno-amino-acids in milk proteins that are well tolerated by breast-fed infants even in high amounts. Se in breast milk occurs as glutathione peroxidase (4-32 % total Se) > selenocystamine > selenocystine > selenomethionine. The wide range of breast-milk Se concentrations depends on Se consumed in natural foods, which reflects the Se content of the soils where they are grown. Se prophylaxis, either through soil Se fertilization or maternal supplements, is effective in raising breast-milk Se concentration. In spite of wide variation, the median Se concentration from studies worldwide are 26, 18, 15, and 17 microg/l in colostrum (0-5 d), transitional milk (6-21 d), mature milk (1-3 months) and late lactation (>5 months) respectively. Se recommendations for infants are presently not achieved in 30 % of the reported breast-milk Se concentrations; nevertheless Se status is greater in breast-fed than in formula-fed infants.

Selenium status and its correlates in a British national diet and nutrition survey: people aged 65 years and over

Plasma selenium (Se) concentrations were measured in 1134 British people aged 65 years and over, living in mainland Britain during 1994-1995. Eight hundred and eighty-three lived in the community ("free-living"), while the remainder lived in institutions (residential and nursing homes). The overall mean plasma Se concentrations was 0.90 micromol/l (inner 95% range 0.50-1.36 micromol/l). Free-living people had significantly higher values than counterparts living in institutions, and there was an overall inverse correlation with age. Plasma Se varied with season (lower from October to December than at other times of the year), while values were higher in southern Britain than in the North. Socio-economic associations also existed (lower plasma Se in people receiving state benefits or with poorer educational attainment), while smokers had lower values than non-smokers. Several indices of poor health status or of medicine use were correlated with lower plasma Se, which was also predicted by several biochemical or haematological indices of infection or inflammation. Plasma Se was strongly and directly correlated with plasma albumin, zinc, cholesterol, vitamin C, several carotenoids, alpha-tocopherol, pyridoxal phosphate, and with blood haemoglobin and several anthropometric indices. All relationships were independent of age and gender, and are consistent with the view that plasma Se levels are higher in fit and well-nourished elderly people and lower in those who are frail, poorly-nourished and unwell. Whole-blood glutathione peroxidase generally did not share these relationships, was only very weakly correlated with plasma Se, and appeared to be less useful as a status indicator in this population group.

Serum selenium levels in healthy Slovak children and adolescents

Blood serum selenium levels were measured in 891 healthy children and adolescents (aged 11-18 yr, 450 girls and 441 boys) residing in both rural and urban areas from eight regions of Slovakia. Subjects were divided into four age groups (11-12 y, 13-14 y, 15-16 y, and 17-18 y). Serum selenium concentration was determined by the electrothermal atomic absorption spectrometric method. The mean (+/-SD) serum selenium concentrations were 0.750+/-0.255 micromol/L in girls and 0.773+/-0.235 micromol/L in boys. A large proportion of the individuals (25.7% in girls, 18.1% in boys) exhibited serum selenium levels under 0.57 micromol/L (45 microg/L). An increasing trend of the serum selenium values with age has been observed in both boys (p < 0.01) and girls (p < 0.05). Boys had higher serum selenium levels in the all age groups but the differences were not statistically significant.

A pilot study of blood antioxidant and free radical marker profiles in patients awaiting coronary artery bypass grafting

Coronary artery bypass grafting (CABG) carries a high risk of acute pancreatitis. We report a pilot study to investigate whether pre-existing oxidative stress might underlie this susceptibility, in that a burst of free radical activity not only accompanies the reperfusion stage of CABG but seems to be a pivotal step in the pathogenesis of pancreatitis. Samples of peripheral venous blood were obtained on the morning of surgery from 8 consecutive patients (age, median and range, 62, 35-70 years) with > 75% stenosis in at least three coronary vessels and a further 8 (64, 49-70 years) who had received 1200 mg allopurinol in divided doses in the previous 48 h: the results were compared with profiles of 8 healthy controls (56, 50-60 years) with normal exercise ECG. None of the patients or controls currently smoked cigarettes and the majority drank alcohol on a social basis. Compared with controls, untreated patients had lower levels of glutathione (P < 0.001) and ascorbate (P < 0.05) in plasma, alpha-tocopherol (vitamin E as molar ratio of cholesterol, P < 0.025 and beta-carotene (P < 0.05) in serum. There was no difference in serum selenium levels, but values in patients and controls were lower than in younger controls from this area (P < 0.02). Samples from the patients contained higher concentrations of lipid peroxides than control samples (P < 0.25) but there was no evidence of excessive isomerisation of linoleic acid or oxidation of ascorbate and erythrocytes showed normal ATP and energy charge with no increase in membrane lipid peroxidisability. Treatment with allopurinol did not alter this pattern, such that the ratio of oxidised to total glutathione in plasma was higher among the 16 patients than 8 controls (P < 0.025). Habitually inadequate intakes are the best explanation for the patients' deficits in aqueous phase antioxidants; prescribed low cholesterol diets would exacerbate any prior insufficiency of lipid-phase antioxidants. Correction of these deficits during the months leading up to surgery should reduce the risk of CABG-induced acute pancreatitis.

Reference values for serum selenium in various areas-evaluated according to the TRACY protocol

Published reports on selenium concentrations in serum and plasma were critically reviewed according to the criteria set up by the expert group of the international project TRACY. The aim was to examine both pre-analytical (sampling conditions and characteristics of the group) and analytical factors described in papers to establish reference values for evaluation of persons with deficiency or excessive exposure to the element. Out of 291 papers published during the period 1983 to 1993, which we reviewed, 36 were considered suitable for the TRACY project. In order to eliminate sources of variation due to age and health status, only data concerning healthy adults were retained. Of the sampling and other pre-analytical factors, geographical area and time of sampling were found to be of high importance. Gender, occupation, diet data and use of supplements or medications were also considered important determinants, but ethnic origin, smoking and fasting, contamination control and storage of sample were held to be of relatively low importance. Concerning analytical factors, accuracy criteria were generally satisfied although not extensively documented. Reference materials for serum selenium, which contribute to better analytical reliability have been available for over 10 years. Due to the geographical variation of selenium intake, one universal reference serum selenium value for the world's population was not feasible but the data selected allowed documentation of the serum selenium concentration levels among populations of different areas, mostly in Europe. Critical use of the published TRACY criteria in future papers will certainly extend their reliability and scientific significance.

Determination of selenium in the serum of healthy Swiss adults and correlation to dietary intake

The serum selenium (Se) concentrations of apparently healthy 20-40 year old blood donors from different parts of Switzerland were determined by electrothermal atomic absorption spectrometry (GFAAS). Application of a rhodium/magnesium matrix-modifier resulted in improved performance in comparison with a palladium modifier. The method was validated by hydride ICP-MS and quality-controlled by independent analysis using GFAAS with palladium as matrix-modifier; no bias was detected. The serum Se concentrations for male (n = 387) and female (n = 243) subjects fell into a normal distribution with mean values and standard deviations of 96.0 +/- 13.3 micrograms/L (1.22 +/- 0.17 mumol/L) and 87.9 +/- 14.4 micrograms/L (1.11 +/- 0.18 mumol/L), respectively. These values corresponded well to the formerly estimated mean daily intakes. Small but significant differences in mean serum Se concentrations were found between genders, ethnic groups as well as geographic regions, whereas age had no influence. The overall Se status of the Swiss population is assessed as adequate, somewhat higher than in the countries adjacent to Switzerland, but lower than in the U.S.A. or Finland. There is no evidence that the Se status of the population has changed over the past 10 years. However, it appears that some Swiss population groups may have a borderline Se status.

Selenium dependent glutathione peroxidase activity in human follicular fluid

The purpose of this study was to evaluate the follicular fluid selenium status of in vitro fertilization patients in relation to their individual characteristics and treatment outcome. A total of 135 samples of follicular fluid were collected from 112 patients during transvaginal oocyte retrieval. Selenium levels and glutathione peroxidase (GSHPx) activity were measured in follicular fluid (FF) and blood serum. A selenium dependent GSHPx activity in follicular fluid has been demonstrated. Patients with unexplained infertility had significantly decreased follicular selenium levels as compared with those with tubal infertility or male factor. The mean GSHPx activity in follicles yielding oocytes which were subsequently fertilized exceeded that of the follicles with non-fertilized oocytes. Tobacco smoking resulted in significantly diminished follicular GSHPx activity. The Se/GSHPx pattern of the FF seems to be significant for the evaluation of the follicular milieu.

Trace element reference values in tissues from inhabitants of the European Community. VII. Review of trace elements in blood, serum and urine of the Belgian population and critical evaluation of their possible use as reference values

The availability of accurate trace element reference values in human tissues represents an important indicator to the health status of the general population and occupational groups exposed to trace elements. The EURO TERVIHT project (Trace Element Reference Values In Human Tissues) aims to establish and compare trace element reference values in tissues from inhabitants of the European Community as baseline values for clinical/toxicological assessment studies (Sabbioni et al., 1992a,b). In this context one of the first steps considered is the critical evaluation (state of the art) of existing literature on trace element reference values in blood, serum and urine in the general population of each EC country. This paper reviews the Belgian situation.

Serum selenium levels in Slovak population

Blood serum selenium levels were measured in 576 healthy middle aged adults (40-60 yr, 255 men and 321 women) residing in both urban and rural areas in four districts of Slovakia. Serum selenium was determined by electrothermal AAS. The mean (+/- SD) serum selenium concentration was 0.852 +/- 0.335 mumol/L, ranging from 0.219-2.30 mumol/L. A large proportion of the individuals (19.62%) exhibited serum selenium levels under 0.57 mumol/L (45 mumol/L). There was no significant correlation between serum selenium concentration and age, sex, and smoking status. There were significant differences between districts. The lowest mean (+/- SD) serum selenium was 0.664 +/- 0.269 mumol/L, the highest mean serum selenium (+/- SD) was 0.975 +/- 0.361 mumol/L. This differences could probably be attributed to the selenium content in the soil of the different areas, which would contribute to the average daily selenium intake. In comparison with serum selenium levels in other European countries, the concentrations of selenium in the Slovak population are relatively low.

Serum selenium in adult Czechoslovak (central Bohemia) population

The serum selenium levels in 367 healthy adult (25-64 yr) Central Bohemia residents, 176 men and 191 women, were determined using atomic absorption spectrometry. An extremely wide range of values was found in the whole population sample (< 20-296 micrograms/L) as well as in each sex or age category studied. The mean selenium concentration and 95% confidence interval calculated after logarithmic transformation of the data were 74 micrograms/L (71-77) for the whole population sample, 72 micrograms/L (67-76) for men, and 76 micrograms/L (72-81) for women. About 10% of the residents exhibited serum selenium level below 45 micrograms/L. There was no significant correlation between serum selenium and sex, age, or smoking status of participants. However, the lowest average level was found in the group of heavy smoking women: 66 micrograms/L. The selenium status of the Central Bohemia population seems to be below European average. Groups of residents having a very low nutritional selenium intake may be expected to occur in this population.

Selenium status of healthy immigrant Parisian preschool children

Plasma selenium (Se) concentration and erythrocyte glutathione peroxidase activity (GPx) were assessed in a population of healthy preschool children two to five years old, residing in the city of Paris. In the 118 subjects, mean (+/- SD) plasma Se concentration was 62.10 +/- 13.96 micrograms/L, and mean GPx activity was 23.58 +/- 8.52 U/g Hb. Mean plasma Se of male children was significantly (p = 0.001) higher (12%) than levels of girls. Plasma selenium levels were not correlated with erythrocyte GPx activity. Children from Mediterranean origin had a slightly lower erythrocyte GPx activity (p < 0.05) than children from other regions. Mean plasma Se concentration of this group corresponded to the lower limit of intervals, which characterizes geographical regions of intermediate selenium concentrations.

Gas chromatographic-mass spectrometric method for the determination of selenium in biological samples

The determination of selenium by capillary gas chromatography-mass spectrometry (GC-MS), using an enriched stable isotope 76Se as internal standard, is described. Reference values for selenium in human biological fluids (serum, red blood cells and urine) are reported. With the advent of new compact capillary GC-MS (benchtop) instruments, this method will be very simple and accurate for routine analysis.

Determination of selenium in blood components by X-ray emission spectrometry. Procedures, concentration levels, and health implications

Sampling, storing, sample pretreatment, and experimental conditions for selenium (Se) determination in human serum, plasma, and whole blood by X-ray emission spectrometric (XRS) methods are described. Concentration levels in these biological fluids, found by this technique, are discussed and compared to values found by other techniques for the same healthy population group in the same area. XRS analysis of blood from patients with various pathological conditions is reviewed, with special attention to the relation of Se with the concentration level of other essential or nonessential trace elements.

Selenium and vitamin E status of healthy and institutionalized elderly subjects: analysis of plasma, erythrocytes and platelets

Levels of selenium in whole blood, plasma, erythrocytes and platelets, glutathione peroxidase (EC 1.11.1.9; GSH-Px) activity in erythrocytes and platelets and vitamin E, low-density-lipoprotein (LDL)-cholesterol and vitamin E: LDL cholesterol in plasma were measured in seventy-five healthy subjects aged less than 65 years and twenty-eight healthy and twenty-three institutionalized elderly people aged greater than 65 years. Healthy elderly subjects had significantly lower levels of Se in whole blood and plasma when compared with younger subjects. Other measurements of Se status were not significantly different. In the healthy subjects plasma levels of vitamin E and LDL-cholesterol increased with age to 60 years and decreased above 80 years. Vitamin E: LDL cholesterol values were not affected by age. Measurements of Se and vitamin E status in the institutionalized elderly compared with the healthy elderly were all reduced with the exception of platelet Se levels and erythrocyte GSH-Px activity. Ageing per se had minimal effect on Se and vitamin E status but intercurrent illness and decreased food intake can lead to reduced levels in the elderly.

Selenium: clinical significance and analytical concepts

Selenium is an essential trace element in humans and animals. Its only established function in humans is the antioxidant activity of glutathione peroxidase, a selenoenzyme. Severe prolonged deficiency may cause a fatal cardiomyopathy. Iatrogenic causes of selenium deficiency include parenteral and enteral nutrition. Low plasma selenium is also found in malabsorption, cystic fibrosis, rheumatoid arthritis, neoplasia, and other varied clinical disorders. Death has resulted from a single massive ingestion of selenium, while chronic excessive intake causes skin, nail, and hair pathology. Extreme geographical variation in population blood and urine selenium levels and a marked age-specific variation in population reference intervals are important factors in understanding selenium nutrition. Nutritional requirements, biological availability, and metabolism are discussed in relation to geographical, age, and method variability. Sampling, processing procedures, and methods for selenium quantitation are reviewed. Selenium content in different biological matrices and reference values for pediatric, adult, and obstetric populations are provided.

Blood glutathione peroxidase : A method for measurement and the influence of storage, cyanide, and Drabkin's reagent on enzyme activity

Manual and automated assays for the determination of glutathione peroxidase activity in bovine, sheep, pig, and human blood samples are described. The reactivation of the enzyme in blood samples after storage at -20°C was examined. Cyanide and Drabkin's reagent, as used to prepare hemolysates in other assays, have been shown to inhibit enzyme activity, particularly in stored blood samples, and is omitted from this assay.

Glutathione peroxidase activity, selenium, and lipid peroxide concentrations in blood from a healthy Polish population : I. Maternal and cord blood

Selenium (Se) concentrations in whole blood and plasma of 19 nonpregnant women. 14 mothers at delivery, 14 neonates, and 13 infants, aged 2-12 mo, were evaluated. The activity of glutathione peroxidase (GSH-Px) in erythrocytes and plasma and the level of lipid peroxides in plasma were also analyzed. Selenium concentrations in whole blood and plasma in mothers at delivery were significantly lower compared to nonpregnant women. Selenium concentrations in cord blood components were lower compared to mothers, but the differences were not significant. The concentration of the element decreased in the first few months of life. Glutathione peroxidase activity in erythrocytes differed only slightly in the examined groups. In plasma, however, the enzyme activity was significantly lower in pregnant compared to nonpregnant women and in neonates compared to their mothers. Lipid peroxide concentrations in plasma differed only slightly in the examined groups. The results obtained are discussed in terms of the observations of other investigators.

Mercury-selenium interaction in workers exposed to elemental mercury vapor

Mercury (Hg) and selenium (Se) levels were determined for erythrocytes, plasma and urine of 25 male and 29 female workers exposed to elemental mercury (Hgo) vapor. Interrelationship between the Hg levels and the Se levels was examined by the correlational analysis and the stepwise regression analysis. Indicators of Se status (erythrocyte Se levels, plasma Se levels and urinary Se levels) were closely intercorrelated; similarly, indicators of exposure to Hgo vapor (erythrocyte inorganic Hg levels, plasma Hg levels and urinary Hg levels) were significantly intercorrelated. Since plasma Hg level was one of the significant independent variables in determining the erythrocyte Se and plasma Se levels, Hgo vapor exposure was thought likely to influence the Se metabolism in workers. None of the Se status indicators were significant as determinants of the indicators of Hgo vapor exposure.

Selenium deficiency

Selenium is undoubtedly an essential trace element: its involvement in GPx structure, the presence of deleterious effects of selenium deficiency in animals, and the recognition of deficiency states in man attest to its importance. However, if the consequences of selenium deficiency in man are now widely recognized, the mechanisms underlying these conditions are poorly understood. The definition of the exact role of selenium in human homeostasis has been hampered by the lack of a sensitive parameter, usable in routine investigation, to assess selenium status. Measurements of plasma and urinary levels, although useful in clinical practice, are inadequate indicators. The only true evidence of selenium deficiency lies in a positive response to selenium therapy. Deficiency states have been demonstrated for inhabitants of regions where selenium supply is limited, in protein-energy malnutrition, and in patients maintained on total parenteral nutrition without selenium supplementation. The benefit of selenium supplementation, together with other antioxidant drugs, in non-deficient subjects is still a matter of debate; its protective effect in neoplastic, cardiovascular and neurological degenerative diseases is not yet proven.

Selenium status in vegans and lactovegetarians

Plasma and urinary selenium were determined among vegans, lactovegetarians and several groups of omnivorous subjects, using gas-liquid chromatography. Plasma Se was lower among lactovegetarians (0.80 (SD 0.18) mumol/l) than in the other groups (0.98 (SD 0.15) mumol/l). This was not related to Se intake, since the vegans had a lower and the lactovegetarians a higher intake of Se than omnivorous subjects in Sweden. Urinary Se was 0.36 (SD 0.10) mumol/d for controls, 0.17 (SD 0.10) mumol/d for vegans and 0.16 (SD 0.07) mumol/d for lactovegetarians. No relation between dietary Se and urinary Se was observed. Among vegetarians, plasma Se and urinary Se were correlated (r 0.51; P less than 0.05).

The selenium status of Belgian population groups : II. Newborns, children, and the aged

The selenium state of 40 elderly Belgian people, residing in geriatric homes, has been evaluated. Data are presented on the selenium (Se) contents of their blood, plasma, and erythrocytes. The activity of glutathione peroxidase (GSH-Px) has been assayed. All data were compared with those obtained for 164 young, working adults as presented in Part I of this study. Plasma selenium levels were significantly lower in the old (73 ng/mL) as compared to the young people (97 ng/mL), but erythrocyte Se levels (200 ng/mL) and GSH-Px activity were significantly higher.The selenium concentration in plasma during infancy has also been estimated. The results reveal a very low Se level during the first months of life, with a gradual increase with age. The results are discussed in the light of literature data.