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PubMed1995

Effect of nationwide selenium supplementation in Finland on selenium status in children with juvenile rheumatoid arthritis. A ten-year follow-up study.

A study was performed on the effect of increased selenium intake on the serum selenium level of 212 children with juvenile rheumatoid arthritis (JRA) and of 214 controls in a follow-up study during the Finnish nationwide selenium fertilization programme, which was started in 1984. The mean serum level of selenium increased from 0.90 mumol l-1 in 1985 to 1.56 mumol l-1 in 1990 in the children with JRA. The corresponding selenium levels in the controls were 0.87 mumol l-1 in 1985 and 1.33 mumol l-1 in 1990. Boys had slightly higher selenium levels in all the age groups among the patients and the controls. During the entire 10-year observation period, the patients with JRA had slightly higher mean levels of selenium than the controls. The age of the children did not have any significant effect on the selenium level in either group. The present study shows that the main factor affecting the serum level of selenium was the dietary intake of selenium both in patients and in healthy controls.

Adolescent↗

PubMed1980

A biological assay for determination of availability of selenium for restoring blood plasma gluthathione peroxidase activity in selenium-depleted chicks.

This study was undertaken to develop an assay for the determination of biological availability of selenium. In a preliminary experiment, commercial male, White Leghorn chicks had significantly reduced glutathione peroxidase activity in blood plasma after 7 days of depletion on a selenium-deficient (0.04 ppm of Se) diet. Selenium-depleted chicks fed graded levels of selenium (0.02--0.10 ppm in steps of 0.02 ppm) for 9 days had glutathione peroxidase activity in blood plasma which was linearly, highly correlated with dietary selenium content. In three subsequent experiments, chicks were fed a selenium-deficient diet for 7 days and were then distributed into groups of five chicks each. The standard diets, which contained 0.02, 0.04, 0.06, 0.08 and 0.10 ppm of selenium added as NaHSeO3, and the test diets, which contained three levels of each test substance and provided selenium supplements within the standard range, were each fed to three groups of chicks for 9 days. The dose parameter was selenium, in the standard groups added as NaHSeO3 and in the test groups provided by the selenium present in the test substance. The response parameter was blood plasma glutathione peroxidase activity. Statistical analyses of the results utilizing four fish meals as test substances revealed that the assay complied with the requirements for statistical and fundamental validity.

Animals↗

PubMed1984

Effects of a low selenium status on the distribution and retention of selenium in the rat.

In the tissues of rats fed a selenium-deficient diet the changes in the selenium content and the retention of the element after administration of a small amount of selenium to the depleted animals were determined. In the liver and in the erythrocytes, which are the main glutathione peroxidase pools, the decrease in the selenium content was great and the retention in the depleted rats only slightly increased in comparison with the control animals fed sufficient amounts of the element. In the testes and in the adrenals the decreases in the selenium content were the smallest, and here retention was about 15 times greater than in the control animals. Also in other tissues, such as the thymus, spleen, bone and kidney, retention was considerably increased in the depleted rats. The results indicate that regulation mechanisms exist, which in nutritional selenium deficiency cause reduced excretion of the element and priority of supply to certain tissues. This, in turn, leads to a redistribution of selenium in the organism and, as the glutathione peroxidase decreases to a greater extent than the selenium, also to a redistribution of the element among its different binding forms. As the selenium content is most probably kept up in particular in sites in which the element is most needed, the findings suggest important functions of selenium in these tissues.

Adrenal Glands↗

PubMed1985

Selenium supplementation in X-linked muscular dystrophy. Effects on erythrocyte and serum selenium and on erythrocyte glutathione peroxidase activity.

The selenium concentrations in serum and erythrocytes and the erythrocyte glutathione peroxidase activity were determined in 15 boys with the Duchenne type and in 5 boys with the Becker type of X-linked muscular dystrophy before and during long-term selenium and alpha-tocopherol supplementation and compared with values in unsupplemented controls. The purpose of the treatment was to improve the muscular strength. Twelve of the 20 patients had pretreatment levels of selenium in serum that were within the 95% confidence limit of the unsupplemented control children. The values in 2 patients, both with the Duchenne type of muscular dystrophy, fell below this level. Selenium supplementation in a daily dose of 6 micrograms/kg/day for 6 months caused a substantial rise in both serum and erythrocyte selenium, suggesting suboptimal pretreatment body contents of selenium. The greatest increases in both serum and erythrocyte selenium were observed in subjects with initially low selenium levels. Only in 4 of the 20 patients did the selenium supplementation result in a significant rise in erythrocyte glutathione peroxidase activity. As no sure improvement was noted in muscular strength during this treatment period, the Se dose was increased to 20 micrograms/kg/day. This resulted in a further rise in both serum and erythrocyte selenium, but not in erythrocyte glutathione peroxidase activity.

Adolescent↗

PubMed1992

Glutathione redox cycle enzymes and selenium in severe rheumatoid arthritis: lack of antioxidative response to selenium supplementation in polymorphonuclear leucocytes.

The antioxidant capacity of the glutathione redox cycle and the concentrations of selenium in serum, red blood cells or whole blood, and polymorphonuclear leucocytes was evaluated in nine patients with severe rheumatoid arthritis (RA) and eight healthy controls receiving daily supplementation with 250 micrograms selenomethionine for six months. Serum and whole blood concentrations of selenium and the activity of the selenium dependent enzyme glutathione peroxidase (GSH-Px) were low in the serum, red blood cells, and polymorphonuclear leucocytes of patients with RA before selenium supplementation. During supplementation serum and whole blood concentrations of selenium and the activity of GSH-Px in serum and red blood cells of patients with RA and serum GSH-Px in controls increased. Selenium and GSH-Px in polymorphonuclear leucocytes were unaffected in patients with RA in contrast with the controls where both were augmented. Glutathione reductase activity in the red blood cells and polymorphonuclear leucocytes of patients with RA was low but increased during selenium supplementation. Whole blood concentrations of glutathione were slightly lower in patients with RA than controls and no difference in the content in polymorphonuclear leucocytes was found between the groups. The activity in red blood cells of glucose-6-phosphate dehydrogenase was high in patients with RA, indicating sufficient function of the hexose monophosphate pathway. The reduced antioxidant activity of the glutathione redox cycle in patients with severe RA was mainly due to the low availability of selenium. This was further supported by the response to selenium supplementation in serum and red blood cells. In the polymorphonuclear leucocytes, however, no biochemical effects of selenium supplementation were seen. This lack of antioxidative response could play a pathogenetic part in inflammation in patients with RA.

Adult↗

PubMed2006

Selenium supplementation of lactating dairy cows: effect on selenium concentration in blood, milk, urine, and feces.

The objectives were to determine effects of graded levels of selenized yeast derived from a specific strain of Saccharomyces cerevisiae (CNCM I-3060) on animal performance and in selenium concentrations in the blood, milk, feces, and urine of dairy cows compared with sodium selenite; and to provide preliminary data on the proportion of selenium as selenomethionine in the milk and blood. Twenty Holstein cows were used in a 5 x 5 Latin square design study in which all cows received the same total mixed rations, which varied only in source or concentration of dietary selenium. There were 5 experimental treatments. Total dietary selenium of treatment 1, which received no added selenium, was 0.15 mg/kg of dry matter, whereas values for treatments 2, 3, and 4, derived from selenized yeast, were 0.27, 0.33, and 0.40 mg/kg of dry matter, respectively. Treatment 5 contained 0.25 mg of selenium obtained from sodium selenite/kg of dry matter. There were no significant treatment effects on animal performance, and blood chemistry and hematology showed few treatment effects. Regression analysis noted significant positive linear effects of increasing dietary selenium derived from selenized yeast on selenium concentrations in the milk, blood, urine, and feces. In addition, milk selenium results indicated improved bioavailability of selenium from selenized yeast, compared with sodium selenite. Preliminary analyses showed that compared with sodium selenite, the use of selenized yeast increased the concentration of selenomethionine in the milk and blood. There was no indication of adverse effects on cow health associated with the use of selenized yeast.

Animal Feed↗

PubMed1990

Dietary selenium intakes and plasma selenium concentrations of formula-fed and cow's milk-fed infants.

The plasma selenium concentrations of 57 infants 8 to 12 months of age were assessed using flameless atomic absorption spectrophotometry. The infants ingested either cow's milk or whey-predominant milk-based infant formula as their primary beverage as part of a mixed diet for at least 3 months. The calculated mean +/- standard deviation (SD) daily dietary selenium intake of 26 infants fed cow's milk (34 +/- 13 micrograms), assessed by a 3-day diet record and/or a 24-hour diet recall, was significantly (p less than or equal to .001) greater than that of 31 formula-fed infants (22 +/- 11 micrograms). The mean +/- SD plasma selenium concentration of infants fed cow's milk (39 +/- 11 micrograms/L) was also significantly (p less than or equal to .05) greater than that of infants fed formula (31 +/- 12 micrograms/L). Both groups of infants ingested similar amounts of total energy; however, the infants fed cow's milk received more total protein and selenium and a greater percentage of protein and selenium from their primary beverage than did the infants receiving formula. Both groups of infants were consuming a mixed diet with similar sources of selenium. To examine the selenium status of infants as well as other individuals better, further analysis of foods is clearly needed to provide more information on dietary selenium sources. The influence of variables such as body size and ethnicity, intake, sources and forms of dietary protein, and dietary forms of selenium on plasma selenium concentrations must also be investigated.

Animals↗

PubMed1988

Effect of selenium supplementation on the distribution of selenium in plasma proteins of healthy subjects.

The influence of an increased intake of selenium on the distribution of this element among plasma proteins was studied. 200 micrograms of yeast selenium was given to healthy subjects daily for 8 weeks, and then the subjects refrained from selenium supplementation for 16 weeks. Plasma selenium increased almost two-fold during supplementation, and most of the increase occurred during the first 4-week-period. Plasma glutathione peroxidase activity increased only marginally. At all times studied, most of the selenium in plasma was located in proteins, migrating close to immunoglobulin G on gel filtration. The selenium content of this fraction was only moderately increased after supplementation for 8 weeks, and instead more marked increases occurred in the regions for high-molecular-weight proteins and albumin. This change implied that the distribution of selenium approached that of total protein, and we therefore conclude that most of the increase in plasma selenium occurred via unspecific incorporation of selenium into a wide variety of proteins. Sixteen weeks after the end of supplementation the selenium distribution had essentially returned to that before supplementation.

Adult↗

PubMed1977

Effects of intramuscular injections of selenium and vitamin E on selenium-vitamin E deficiency in young pigs.

Effects of intramuscular injections of selenium and vitamin E on lesions in pigs with selenium-vitamin E deficiency syndrome were determined in 2 factorial experiments, using a total 69 pigs. The pigs were fed a selenium-vitamin E deficient, 22.3% protein ration, supplemented with methionine, minerals, and vitamins. Weekly intramuscular injections of isotonic saline solution, vitamin E, selenium, or vitamin E and selenium were given to the respective treatment groups. Selenium-vitamin E deficiency lesions occurred only in pigs that were given saline injections. Weekly intramuscular injections of either selenium (as selenous acid buffered to pH (7.3) at the rate of 0.05 mg/kg of body weight or vitamin E at the rate of 20 IU/kg of body weight or the combination of selenium and vitamin E prevented cardiac and skeletal myodegeneration, hepatic necrosis, and death. Significant increases of serum aspartate aminotransferase activity values were noted in pigs with liver, heart, or skeletal muscle lesions, but these increases were not correlated with the extent of the lesions. Vascular lesions, epicardial and endocardial hemorrhages, and yellow discoloration of body fat were not features of this experimentally induced disease. These lesions may be related to factors other than the deficiency of selenium, vitamin E, or selenium and vitamin E in rations previously used in reported studies.

Animals↗

PubMed1997

Effects of water supplementation with selenium and vitamin E on growth performance and blood selenium and serum vitamin E concentrations in weanling pigs.

OBJECTIVE: To determine effects of supplementation of drinking water with selenium and vitamin E on blood selenium and serum vitamin E concentrations, growth performance, and water intake of pigs. DESIGN: Prospective controlled study. ANIMALS: 228 weanling pigs. PROCEDURE: In experiments 1 and 2, pigs were given drinking water supplemented with selenium and vitamin E, and blood selenium and serum vitamin E concentrations were measured. In experiment 3, growth performance and water intake were measured in pigs that received supplemented water for 2 or 5 weeks and in control pigs. RESULTS: In experiment 1, blood selenium concentrations were significantly increased after 7 days of supplementation, and serum vitamin E concentrations were significantly increased after 1 and 7 days of supplementation, compared with baseline concentrations. In experiment 2, blood selenium concentrations were not significantly different between treated and control pigs, and serum vitamin E concentrations were significantly increased on day 7. In experiment 3, gain-to-feed ratios were significantly higher for pigs supplemented with selenium and vitamin E for 5 weeks, but other differences were not detected. CLINICAL IMPLICATIONS: Supplementation of drinking water with selenium and vitamin E may improve the selenium and vitamin E status of weanling pigs by increasing selenium and vitamin E intake.

Analysis of Variance↗

PubMed2005

Laser ablation synthesis of selenium superoxide anion SeO4- via selenium trioxide photolysis. Time-of-flight mass spectrometry and ab initio calculations.

Laser desorption/ionisation and laser ablation of solid selenium trioxide, as well as the gas-phase behaviour of selenium trioxide, were studied. Selenium trioxide undergoes photochemical decomposition and, from the mass spectra obtained by laser desorption/ionisation time-of-flight mass spectrometry (LDI-TOF-MS), the following species were identified: O-, O2-, O3-, SeO-, SeO2-, SeO3-, SeO4-, Se2O7-, Se3O11-, and Se4O14-. Formation of the selenium superoxide SeO4- anion is described in this work for the first time. In addition, low-abundance selenium species such as Se2O8H2-, Se3O11H-, and Se4O15H2- were also detected. The stoichiometry of all ions was confirmed via isotopic pattern modeling and/or post-source decay (PSD) analysis. Photolysis of selenium trioxide leads partly to ozone formation. It was found that the most likely mechanisms of selenium superoxide formation are oxidation of selenium trioxide with ozone and/or reactive oxygen radicals, or photolysis of selenium trioxide tetramer (SeO3)4. Therefore, ab initio calculations were performed to support the mass spectrometric evidence and to suggest probable geometries for selenium superoxide anion SeO4- and diselenium superoxide anion Se2O7-, as well as to provide insight into and/or predict possible formation pathways. It has been found that both cyclic and non-cyclic peroxide structures of SeO4- and Se2O7- ions are possible. In addition, the SeO4 structure was also calculated guided by thermodynamic considerations using Gaussian-2 methodology, and the inferred stability of the SeO4 neutral molecule was supported by ab initio calculations.

Journal Article↗

PubMed1991

Selenium metabolism and platelet glutathione peroxidase activity in healthy Finnish men: effects of selenium yeast, selenite, and selenate.

The mean dietary selenium intake in Finland increased from 40 to 100 micrograms/d in 1987 because of the addition in 1985 of selenium to fertilizers. A selenium-supplementation study was performed in 1987 on the same men as were followed in a 1981 study that had a similar design (200 micrograms Se/d). Selenite and selenate, but not selenium yeast increased platelet glutathione peroxidase (GSHPx) activity by 30% compared with placebo, much less than the 70% found in the previous study. Selenium yeast and selenite increased plasma selenium after 11 wk from 1.39 mumol/L to peak values of 2.15 and 1.58 mumol/L, respectively. Only yeast selenium was incorporated into red cells. From a regression plot based on present and literature data, it was estimated that the plasma selenium concentration needed to achieve maximal platelet GSHPx activity was 1.25-1.45 mumol/L. At the present selenium intake in Finland, 100 micrograms/d, GSHPx activity is saturated in plasma and red cells and almost saturated in platelets.

Analysis of Variance↗

PubMed1993

Significance of selenium-labeled proteins for selenium's chemopreventive functions.

A 58 kDa selenium-labeled protein purified from mouse mammary epithelial cells (MMEC) was used to examine whether selenium modulates protein synthesis or is just a marker for cellular selenium status. The protein was isolated using Sephadex G150 gel filtration and DEAE-Sephadex A50 ion-exchange chromatography. It was further analysed using 2-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and was found as a single spot with a pI of 4.6. The immunoreactivity with anti-58 kDa antiserum and the 75Se signal co-localized on a single 58 kDa protein band on both 1D- and 2D-PAGE. Partial amino acid analysis of the peptide showed homology with the thiol protein disulfide oxidoreductase (TPDO). Varying the selenium concentration in culture medium did not affect the protein content or the immunoreactivity of the 58 kDa protein. Additionally, selenium did not seem to regulate the activity of TPDO in TM6 cells. The glutathione peroxidase activity of TM6 cells, taken as the internal positive control, was enhanced with the increase in selenium concentration in the medium. The results suggest that selenium is attached to the 58 kDa protein, but does not regulate either its protein synthesis or its functional activity. We conclude that selenium labeling of the 58 kDa protein reflects the cellular selenium status but probably is not involved in its chemopreventive ability.

Amino Acid Sequence↗

PubMed1995

Iodothyronine deiodinase activity in methionine-deficient rats fed selenium-deficient or selenium-sufficient diets.

We examined the effect of methionine deficiency on iodothyronine 5'-deiodinase activity in selenium-deficient rats or selenium-sufficient rats fed sodium selenate or selenomethionine. Forty-two weanling male Wistar rats were divided into six groups and pair fed the respective purified L-amino acid-based diets for 4 wk. L-methionine concentrations in the diet were 8.0 g/kg for sufficient rats, and 2.0 g/kg for deficient rats. Selenium concentrations in the diet were 0.5 mg/kg (as sodium selenate or selenomethionine) for selenium-sufficient rats and less than 0.005 mg/kg for selenium-deficient rats. Type I 5'-deiodinase activities were significantly lower in liver and higher in kidney of methionine-deficient rats than in those of methionine-sufficient rats fed either the selenium-sufficient or the selenium-deficient diets. The type I 5'-deiodinase activity in brain was significantly lower in the methionine-deficient rats than in the methionine-sufficient rats fed the selenium-deficient diet. Type II 5'-deiodinase activity in brain was significantly higher in the methionine-deficient rats than in the methionine-sufficient rats fed selenium-sufficient diet as sodium selenate. Both thyroxine and 3,3',5-triiodothyronine concentrations in plasma were significantly higher in the methionine-deficient rats than in the methionine-sufficient rats. It is suggested that the methionine deficiency affects the 5'-deiodinase activity and thyroid hormones level in the rats.

Animals↗

PubMed1978

Selenium and cancer: effects of selenium and of the diet on the genesis of spontaneous mammary tumors in virgin inbred female C3H/St mice.

Inbred female C3H/St mice exhibit the normal incidence of spontaneous mammary adenocarcinoma of 80--100% if they are maintained on a standard commercial laboratory diet containing 0.15 ppm of selenium with meat and dried skimmed milk as major sources of protein. The tumor incidence drops to 42% if animals of the same strain are kept on a diet containing 0.45 ppm of selenium, with fishmeal as the main source of protein. The tumor incidence declines further to 25, 19 and 10% if the animals in addition receive 0.1, 0.5, and 1.0 ppm of selenium in the drinking water. Selenium supplementation at these levels has no noticable adverse effects on weight-grains and survival of the mice. Selenium supplmented groups of animals also remained tumor-free for longer periods than the unsupplemented controls. The results of this study indicate that a diet rich in seafoods and cereals provides more selenium and may in turn lower the probability of cancer development. Reference is made to the average human diet in the U.S.A., which only contains 0.07--0.15 ppm of selenium due to the comparatively low consumption of cereals and seafoods. An equivalent mouse diet would not have any cancer-protecting effect in the C3H/St mice of our study. Australian workers have reported significantly lower tumor incidence in a different strain of C3H mice if it was kept in Australia rather than in the U.S.A. We have found that the Australian feed contained three times more selenium than that employed in the U.S.A. and propose that this difference in selenium content was primarily responsible for these previous observations.

Animals↗

PubMed1980

Sulfur--selenium studies in sheep. II. Effect of a dietary sulfur deficiency on selenium and sulfur metabolism in sheep fed varying levels of selenomethionine.

The effect of a sulfur deficiency on the metabolism of selenium and sulfur was investigated in eight merino wethers. The sheep were fed high-sulfur (2 g S/kg) or low-sulfur (0.5 g S/kg) diets for two periods of 35 days each, and received selenium as selenomethionine at dietary concentrations of 0.02, 0.06, 0.09 and 0.67 mg Se/kg. Sheep fed the low-sulfur diet had reduced feed intake, reduced nitrogen, sulfur and selenium balance, but elevated plasma and wool selenium concentrations. Selenium concentrations in organs and tissues of slaughtered animals paralleled the selenium intake of the animal, with the renal cortex containing the highest concentration and bone the lowest. The effect of the 0.5 g S/kg diet on feed intake is in contrast with the results from the previous experiment (White and Somers 1977) using 0.7 g S/kg. It is this difference in fed intake which was responsible for many of the effects on selenium metabolism observed in this experiment. Once the feed intake effects are accounted for, the implications for sulfur--selenium interactions remain as before, i.e. more selenium is incorporated into wool and plasma protein when dietary sulfur is limiting than when it is not.

Animals↗

PubMed2004

An increase in selenium intake improves immune function and poliovirus handling in adults with marginal selenium status.

BACKGROUND: Dietary selenium intakes in many countries, including the United Kingdom, are lower than international recommendations. No functional consequences of these lower intakes have been recognized, although experimental studies suggest that they might contribute to reduced immune function, increased cancer incidence, and increased susceptibility to viral disease. OBJECTIVE: The objective was to assess whether administration of small selenium supplements to otherwise healthy UK subjects leads to functional changes in immune status and the rates of clearance and mutation of a picornavirus: live attenuated polio vaccine. DESIGN: Twenty-two adult UK subjects with relatively low plasma selenium concentrations (<1.2 micromol/L, approximately 60% of those screened) received 50 or 100 microg Se (as sodium selenite) or placebo daily for 15 wk in a double-blind study. All subjects received an oral live attenuated poliomyelitis vaccine after 6 wk and enriched stable (74)Se intravenously 3 wk later. RESULTS: Selenium supplementation increased plasma selenium concentrations, the body exchangeable selenium pool (measured by using (74)Se), and lymphocyte phospholipid and cytosolic glutathione peroxidase activities. Selenium supplements augmented the cellular immune response through an increased production of interferon gamma and other cytokines, an earlier peak T cell proliferation, and an increase in T helper cells. Humoral immune responses were unaffected. Selenium-supplemented subjects also showed more rapid clearance of the poliovirus, and the poliovirus reverse transcriptase-polymerase chain reaction products recovered from the feces of the supplemented subjects contained a lower number of mutations. CONCLUSIONS: The data indicate that these subjects had a functional selenium deficit with suboptimal immune status and a deficit in viral handling. They also suggest that the additional 100 microg Se/d may be insufficient to support optimal function.

Adult↗

PubMed1989

Increased plasma and erythrocyte selenium concentrations but decreased erythrocyte glutathione peroxidase activity after selenium supplementation in children with Down syndrome.

An investigation was made of the activity of glutathione peroxidase (GSH-Px) in erythrocytes and the levels of selenium in plasma and erythrocytes before, during and after selenium supplementation in children with Down syndrome (DS). This subject is of interest since it has been suggested that selenium supplementation could enhance the GSH-Px activity in erythrocytes, probably leading to improved protection against oxygen radicals, which might cause damage by lipid peroxidation, especially in the brain. Forty-eight children with DS were treated with selenium-rich yeast tablets (10 micrograms/kg body weight/day) for 6 months. The supplementation was well tolerated and no side effects were observed. Selenium supplementation resulted in increased concentrations of selenium both in plasma and erythrocytes, but decreased GSH-Px-activity in erythrocytes. Plasma and erythrocyte selenium levels but almost regained the initial values 12 months after termination of the supplementation. Erythrocyte GSH-Px activity, on the other hand, remained reduced and did not return to the presupplementation levels. Until we gain more knowledge about the biological functions of selenium in man and the role of oxygen metabolism in the development of presenile dementia in DS, universal selenium supplementation in DS patients cannot be recommended.

Adolescent↗