Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Selenium”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 613 records · Page 34Linked to original sources
PubMed2001

[Nutritional consideration for changes in dietary habit and health promotion practices in community health care; from the view point of selenium].

The Japanese recommended dietary allowances (RDA) for major and some minor nutrients were revised in 1999, and included those for trace elements such as selenium. The requirement of selenium in animals was first recognized in 1957. It has been shown that cellular glutathione peroxidase (GPx) contains selenium but it was subsequently revealed that selenium has diverse biochemical effects, rather than simply functioning in the enzyme. At least twelve different selenoproteins have been identified. The role of selenium has been known as antioxidant, and non-antioxidant mediated through these enzymes. Now, selenium is well recognized as a preventive factor for cancer and cardiovascular diseases. Several dietary studies have shown that the selenium intake in Japan is adequate. One study estimated daily selenium intake to be 104.2 micrograms/day for adults. This value was 2 or 3 times higher than the lower limit of the safe range of dietary selenium (40 micrograms/day for men and 30 micrograms/day for women) estimated by WHO, and also exceeded the newly established RDA of 55-60 micrograms/day for men and 45 micrograms/day for women by the Japanese Public Health Council. However, the established RDA for selenium is tentative because of a lack of information on the 1) chemical forms of selenium in food, 2) differences in absorption rate and bio-availability in the chemical forms, and 3) interactions with other metals and trace elements. There are two potential problems concerning selenium nutrition in Japan. The first problem is that rice, which is the Japanese staple food, contains less than 0.05 microgram/g selenium whereas U.S. rice contains more than 0.3 microgram/g, probably due to differences in soil chemistry. The second problem is that although studies have shown that seafood, fish, shellfish and oysters, contain high levels of selenium (0.4-0.5 microgram/g), these being the main selenium source for Japanese, the bio-availability in fish is low. Thus, it is likely that the selenium status of those Japanese who eat an imbalanced diet is not sufficient or is not optimal even if the intake exceeds the RDA. Further studies are needed so that community health care specialists have available appropriate knowledge on the role of trace nutrients, including selenium, in human nutrition and health, to promote proper nutritional practices in the community.

Adolescent↗
PubMed1990

An investigation of bulk tank milk selenium levels in the San Joaquin Valley of California.

We evaluated selenium determination of bulk milk tank samples as an alternative to testing blood selenium for evaluating herd selenium status in DHIA dairy herds in the San Joaquin Valley of California. A method of determining milk selenium levels using inductively coupled plasma spectrometry is described. Mean bulk tank milk selenium levels were 0.0224 mg/L (Range 0.0126-0.0418 mg/L). No statistically significant relationships were found between bulk tank milk selenium levels of a herd and calving interval, days open or log somatic cell counts. Mean herd blood and milk levels were directly proportional to bulk tank milk selenium levels. Within a herd milk selenium levels of a cow were directly proportional to the cow's blood selenium level. Herd selenium levels were not significantly related to soil selenium levels. Determination of bulk tank milk selenium levels has the potential to be a low cost, non-invasive means of evaluating herd selenium levels in order to determine selenium deficiency. Further studies with this technique in areas which are deficient in selenium may provide estimates of the sensitivity, specificity and predictive value of bulk milk tank selenium for determining selenium deficiency in dairy herds.

Analysis of Variance↗
PubMedDate not supplied

Correlations of blood selenium with hematological parameters in West German adults.

The serum selenium and the whole blood selenium of 72 healthy persons (47 women, 25 men) was determined. There exist sex specific differences of the whole blood selenium between men (98 +/- 19 micrograms Se/L) and women (89 +/- 17 micrograms Se/L). The serum selenium did not show sex specific differences, but sex specific differences are found if the total amount of extracellular selenium is calculated by correction of the serum selenium with the hematocrit. Women have more extra-cellular selenium/L whole blood (40 +/- 8 micrograms Se) than men (36 +/- 7 micrograms Se). Men have more intraerythrocyte selenium (cellular selenium = 67 +/- 14 micrograms Se) in one L whole blood than women (52 +/- 17 micrograms Se). There exist also sex specific differences if the cellular selenium is calculated/g hemoglobin (men .44 micrograms Se/g Hb, women .37 micrograms Se/Hb) or per erythrocyte (men 136.1 x 10(-19) g Se/Ery, women 113.9 x 10(-19) g Se/Ery). In the cellular compartment of one L whole blood on the average 1.56 times more selenium is present than in the extracellular compartment. Most of the intraerythrocyte selenium is hemoglobin bound (84%) and utmost 16% glutathione peroxidase associated. An erythrocyte contains about 3500 mol glutathione peroxidase, or, for every 80000 mol hemoglobin one mol glutathione peroxidase. A standard man needs about 2.5 micrograms selenium/d for the synthesis of the hemoglobin and the erythrocyte. The hematological parameters hemoglobin and the erythrocyte number are correlated with the cellular selenium and the ratio cellular selenium/extracellular selenium. Positive significant correlations are found that are best if a parabolic model is used to interpret the shape of the curves. From the shape of the best correlation lines it can be concluded that selenium may be beneficial for hemoglobin synthesis and erythropoesis. The extracellular selenium may have influence on the volume of the erythrocyte by protecting the outer erythrocyte membrane from lipid peroxidation. A method is reported based on the carbon furnace atomic absorption spectroscopy, which is able to determine without wet digestion selenium in whole blood.

Adult↗
PubMed1985

Projected uptake and toxicity of selenium compounds from the environment.

Industrial workers and members of the general public may be exposed to selenium by inhalation of selenium in the workplace or atmosphere or by ingestion of selenium in food. A model has been developed to evaluate the potential uptake of selenium in body tissues by these two exposure routes. Rates were estimated for transport of selenium between five compartments including lung, gastrointestinal tract, blood, liver and other tissues. Results of model simulations were compared to published tissue distribution information obtained from single inhalation exposures of rats and dogs to radiolabeled selenium compounds at concentrations from 20 mg/m3 to 20 micrograms/m3 with initial body burdens of selenium ranging from 28 to 0.09 micrograms Se/kg body wt. The model was then modified to predict equilibrium organ concentrations of selenium in people after continual exposure to selenium in the air or in the diet. Daily intake levels of 100 micrograms/day and a fractional absorption value of 0.8 were used. With an air concentration of 1 ng Se/m3, model predictions indicated that most of the total body selenium in people is likely to come from their diet because selenium in the urban atmosphere contributes a very small part of the total body selenium. However, continual inhalation of selenium at the threshold limit value (TLV; 200 micrograms/m3) could contribute significantly to the total body burden of selenium. Levels of selenium predicted in lung, liver, and blood after inhalation of selenium at the TLV were 22,000, 1200, and 440 ng Se/g tissue. Predicted lung concentrations were near those that produced toxic effects in animals after ingestion of Se.

Absorption↗
PubMed2002

Selenium incorporation into Saccharomyces cerevisiae cells: a study of different incorporation methods.

AIMS: To study the effects of the selenium enrichment protocols in yeast at various points in the cell cycle, total selenium accumulation and the forms of selenium incorporated. METHODS AND RESULTS: The use of selenized yeast as enriched selenium supplements in human nutrition has become a topic of increasing interest over the last decade. Four enrichment procedures have been evaluated using sodium selenite as the selenium source: enrichment during the growth phase; enrichment at the non-growth phase, both of these at different selenium levels; enrichment by seeding in a fermentable carbon source (glucose); Se-enrichment with a non-fermentable carbon source (glycerol). A nitric acid digestion of the yeast samples prepared under different conditions has been performed in order to evaluate the total selenium incorporated into the yeast cells. Also, an enzymatic digestion of the yeast samples with pepsin has been carried out as an initial step to begin the process of determining which of the different possible selenium species are formed. The cell count evaluations of the selenium-enriched yeast showed that the growth phase, seeding and the use of YEPG media is influenced by the addition of Se, while the non-growth phase is not. Total selenium incorporation studies showed that seeding the yeast permits more accumulation of selenium. Speciation studies of the enriched yeast showed that the growth phase increases the formation of L-Se-methionine. CONCLUSIONS: When the aim of enriching yeast with selenium is the formation of L-Se-methionine, the best enrichment procedure is using the growth phase with small concentrations of sodium selenite. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of selenium supplements is widespread and most of the supplements use selenium-enriched yeast in their formulation. Studies made on supplements do not have the appropriate Se-species for optimal absorption in the human body. This study presents and compares methods for the best selenium yeast enrichment that could ultimately be used in selenium supplement formulations.

Colony Count, Microbial↗
PubMed1984

Effect of dietary selenium on plasma selenoprotein P, selenoprotein P1 and glutathione peroxidase in the rat.

The purpose of this study was to determine the effect of dietary selenium on the abundance of selenium in plasma selenoprotein P, selenoprotein P1 and glutathione peroxidase. Weanling rats were provided water that contained 1.0, 0.1 or 0.01 ppm selenium and 75Se for 21 days. Gel filtration of denatured subunits was used to identify 75Se in the selenoproteins. Rats provided 1.0 ppm selenium accumulated 1.5 times more 75Se in liver cytosolic selenoprotein P1, but not in the two other selenoproteins, than did rats provided 0.1 ppm selenium. Most of the liver and blood selenium in rats provided 1.0 ppm selenium was insoluble and in an unknown chemical form. The tissue accumulation of unrecoverable selenium was apparently a response to the high dietary level of selenium. The proportion of selenium in plasma selenoprotein P, a putative selenium-transport protein, reflected the long-term selenium status of rats and varied from approximately 11-58% depending on the level of selenium supplementation. Turnover of selenium from this protein was affected by the dietary selenium of the rats. The results indicate that selenium incorporation into plasma selenoprotein P and selenoprotein P1 is affected by diet in ways that may reflect their importance to the rat.

Animals↗
PubMedDate not supplied

Report on the 1986 A.S.P.E.N. Research Workshop on selenium in clinical nutrition.

Selenium in human nutrition was the theme of the 1986 Research Workshop of the American Society for Parenteral and Enteral Nutrition. At the workshop, evidence for the nutritional essentiality of selenium to humans was reviewed, and it was concluded that Keshan disease, the cardiomyopathy of children and young women described in China, is now firmly linked to selenium deficiency, although other factors may be involved. Selenium metabolism and techniques for assessing selenium status also received attention at the workshop. A measurement of blood selenium levels was accepted, in general, as a valid technique for assessing selenium status in individuals with relatively constant selenium intakes. Clinical practitioners at the workshop reported that some of their total parenteral nutrition patients not receiving selenium presented biochemical evidence of selenium deficiency, but no characteristic clinical syndrome due to selenium deficiency has yet been observed in such patients. The workshop attendees acknowledged the need for an official guideline for selenium use in total parenteral nutrition, but were unable to develop a consensus regarding such a guideline. However, the workshop agreed that any guideline established in the future should specify the type of patients to be supplemented, the dose of selenium to be administered, and the selenium compound to be used. Until that time, the physician supervising the therapy must assume responsibility both for determining the need for selenium supplementation, and for the administration of the supplemental selenium.

Adult↗
PubMed2002

Effects of selenium on the structure of the mandible in experimental diabetics.

In the treatment of diabetes-induced pathologies, beneficial results have been obtained with administration of antioxidants. Selenium is an antioxidant and essential trace element in living organisms. The aim of this study was to investigate the possible effects of selenium on the structural alterations of the mandible due to diabetes. In this study thirty-nine Wistar rats were used and a control, a selenium given control, a diabetic and a selenium given diabetes groups were formed. Experimental diabetes was induced by a single i.p. injection (50 mg/kg) of streptozotocin (STZ). The diabetic + selenium and the control + selenium groups were injected with a daily dose of 5 micro mol/kg/day sodium selenite (i.p.) for 4 weeks while the diabetic and the control groups were injected with distilled water. Mandibles of all the animals were excised and examined at the 5th week. High blood glucose level and low body weight in the diabetic group were not significantly affected by selenium administration. Furthermore, a negligible increase in blood glucose level was observed in the selenium given control group. Densitometric analysis revealed a significant reduction in bone density and presence of resorption in the diabetic and the selenium given control groups as compared to the selenium given diabetes and the control groups. In X-ray diffraction analysis, the reduction in peak intensity of the reflected light in both the diabetic and the selenium given control groups indicated a possible alteration in the crystallinity or a poor crystalline substance. Histological investigation showed that there was progressive resorption, trabecular and cortical irregularity and vascular proliferation in the diabetic and the selenium given control groups, whereas a more healthy appearance was detected in the selenium given diabetes group. The results of this study suggest the positive effects of selenium on diabetes-induced structural alterations in the mandible. However, the unexpected results in the selenium given control group necessitate further studies on the mechanism of selenium effects in organisms.

Absorptiometry, Photon↗
PubMed1975

Selenium in ruminant nutrition: a review.

The early interest in selenium related primarily to its toxicity, but since 1957 the element has been recognized as a dietary essential. The dietary requirement for selenium by most species is about .1 ppm. Deficiencies of selenium in cattle and sheep have been confirmed under natural grazing conditions in many countries of the world. Overt signs of inadequacy such as white muscle disease (nutritional muscular dystrophy) occur primarily in young calves or lambs born to selenium deficient dams. Infertility has increased in ewes grazing pastures low in selenium. In general, signs of deficiency have not occurred in older animals such as finishing beef cattle and lactating dairy cows. Subclinical deficiencies of selenium are not determined easily, however, and thus an inadequacy of the element may be limiting maximum animal performance under certain circumstances of drylot feeding. The current nutritional status of ruminant animals in many geographical areas and involving various feeding programs with this element has not been established. The recent widespread deficiency problems with nonruminants suggest that such an assessment should be made. Concentration of selenium in tissue, particularly in the liver, has been used in establishing selenium status of the animal. With lambs glutathione peroxidase activity in certain tissues may be a more accurate indicator of selenium adequacy than is selenium content of the tissue. Supplemental sodium selenite and sodium selenate by either oral administration or parenteral injection have prevented clinical signs of selenium deficiency and animal losses in both ruminant and nonruminant animals. Heavy pellets containing elemental selenium for placement in the rumen have proved effective. In general, organic forms of selenium are absorbed more readily by animals than are inorganic compounds. The dietary requirements for selenium and its metabolism are influenced by many nutrient interrelationships, including its interactions with sulfur, lipids, vitamin E, proteins, amino acids, and several microelements. The Food and Drug Administration gave approval in 1974 for the oral administration of supplemental selenium as either sodium selenite or sodium selenate to certain classes of swine and poultry. Similar approval in the United States for ruminants will require additional information, particularly with regard to the influence of dietary intake on concentrations of selenium in tissue and milk in beef and dairy animals.

Animal Feed↗
PubMed1984

Maternal transfer and retention of supplemental selenium in neonatal calves.

Selenium concentrations in blood serum of heifer calves from dams fed 0, 1, or 5 mg supplemental selenium daily during the dry period were compared. Dry cows were fed corn silage top dressed with a soybean meal mineral mix containing the desired amount of selenium. At birth, calves were assigned to one of six treatments in a 3 x 2 factorial arrangement. Calf treatments were 0, 1 (at birth), or 2 (at birth and 14 days of age) injections of selenium/vitamin E with feeding of starter commencing at 14 or 28 days of age. Dosage per injection was .078 mg selenium and 5.4 IU vitamin E per kilogram body weight. Selenium concentrations of blood serum of cows at parturition were 14, 32, and 58 ppb for cows fed 0, 1, and 5 mg selenium per day. Amount of selenium fed to cows affected selenium concentrations in blood serum of their calves with those from cows fed 5 mg selenium having the greatest concentrations. Calves from cows fed no supplemental selenium showed increased selenium in serum at day 28 and 42 when given one or two injections of selenium. Two injections, however, were necessary to elicit a response in calves from cows fed 1 mg per day. Selenium in blood serum of calves from cows fed 5 mg per day was not elevated when calves were given one or two injections of selenium. Prepartum selenium supplementation of the dam elevated selenium of blood serum in the calf at birth.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed2006

Primary school children from northeast Thailand are not at risk of selenium deficiency.

Selenium has important roles as an antioxidant, in thyroid hormone metabolism, redox reactions, reproduction and immune function, but information on the selenium status of Thai children is limited. We have assessed the selenium status of 515 northeast Thai children (259 males; 256 females) aged 6 to 13 years from 10 rural schools in Ubon Ratchthani province. Serum selenium (n=515) was analyzed by Graphite Furnace Atomic Absorption Spectrophotometry and dietary selenium intake by Hydride Generation Absorption Spectrophotometry from one-day duplicate diet composites, from 80 (40 females; 40 males) randomly selected children. Inter-relationships between serum selenium and selenium intakes, and other biochemical micronutrient indices were also examined. Mean (SD) serum selenium was 1.46 (0.24) micro mol/L. Concentrations were not affected by infection or haemoglobinopathies, but were dependent on school (P< 0.001), sex (P=0.038), and age group (P=0.003), with serum zinc as a significant covariate. None of the children had serum selenium concentrations indicative of clinical selenium deficiency (i.e. <0.1 micro mol/L). Significant correlations existed between serum selenium and serum zinc (r= 0.216; P < 0.001), serum retinol (r = 0.273; P < 0.001), urinary iodine (r = -0.110; P = 0.014), haemoglobin (r = 0.298; P <0.001), and haematocrit (r = 0.303; P< 0.001). Mean (SD) dietary selenium intake was 46 (22) micro g/d. Children with low serum selenium concentrations had a lower mean selenium intake than those with high serum selenium concentrations (38 +/- 17 vs.51 +/- 24 micro g/d; P< 0.010). In conclusion, there appears to be no risk of selenium deficiency among these northeast Thai children.

Adolescent↗
PubMed1985

Effects of dietary selenium concentration on the development of enzyme-altered liver foci and hepatocellular carcinoma induced by diethylnitrosamine or N-acetylaminofluorene in rats.

Three protocols were used to determine the effects of dietary selenium concentration on the development of gamma-glutamyl-transpeptidase (GGT)-positive foci and hepatocellular carcinoma induced by either diethylnitrosamine (DEN) or N-acetylaminofluorene in rats. In the first experiment, foci were induced by a carcinogenic dose of DEN (100 mg/kg body weight, p.o.) at 20-22 h after two-thirds partial hepatectomy. One wk after DEN administration, during which time 0.1 ppm (representing a control level), 3.0, or 6.0 ppm selenium as Na2SeO3 was fed for 8 or 16 wk, at which time focal analysis was conducted using quantitative stereology. The results demonstrated that 3.0 and 6.0 ppm dietary selenium, initiated 1 wk following carcinogen administration, decreased focal growth rate without affecting the number of GGT foci compared to 0.1 ppm selenium. Decreased focal growth was temporary and reversible with 6.0 ppm selenium which may be related to chronic selenosis observed after 16 wk of 6.0 ppm selenium feeding. A second experiment involved a noncarcinogenic dose of DEN (25 mg/kg body weight, p.o.), then 0.1 or 6.0 ppm selenium feeding for 8 wk, followed by 0.05% phenobarbital (PB), a liver tumor promoter in a diet containing 0.1 ppm selenium. Analysis of GGT foci at 5 or 8 wk of PB feeding indicated that 6.0 ppm selenium caused a trend towards an increase in the number of foci/cm3 of liver and mean focal volume and a significant increase in GGT focal volume as a percentage of liver volume by 8 wk of PB feeding. Thus, high dietary selenium concentrations prior to PB enhance the tumor-promoting ability of PB. In a third experiment, using male Fischer 344 rats (150 g), 0.1 or 6.0 ppm selenium was fed concurrently with 0.02% AAF which was fed in a cyclic regimen. After 4 cycles, where 1 cycle equalled 4 wk of AAF, followed by 1 wk of control diet (0.1 ppm selenium), 6.0 ppm selenium significantly decreased the mean focal volume and focal volume as a percentage of liver volume, while not affecting the number of foci/cm3 of liver, again indicating a selenium effect on focal growth while not affecting the number of "preneoplastic" lesions in the liver. Six ppm selenium feeding after AAF treatment had no effect on the percentage of incidence of hepatocellular carcinoma (100%) but did cause a significant decrease in the percentage of liver volume occupied by macroscopic subcapsular liver lesions compared to 0.1 ppm selenium.(ABSTRACT TRUNCATED AT 400 WORDS)

2-Acetylaminofluorene↗
PubMed2003

Selenium supplementation to prevent short-term morbidity in preterm neonates.

BACKGROUND: Selenium is an essential trace element and component of a number of selenoproteins including glutathione peroxidase, which has a role in protecting against oxidative damage. Selenium is also known to play a role in immunocompetence. Blood selenium concentrations in newborns are lower than those of their mothers and lower still in preterm infants. In experimental animals low selenium concentrations appear to increase susceptibility to oxidative lung disease. In very preterm infants low selenium concentrations have been associated with an increased risk of chronic neonatal lung disease and retinopathy of prematurity. OBJECTIVES: To assess the benefits and harms of selenium supplementation in preterm or very low birthweight infants. SEARCH STRATEGY: Searches were made of the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2003), MEDLINE (1966-May 2003), and Embase (1980-May 2003). The reference lists of recent trials were also searched and abstracts from the Society for Pediatric Research from 1990 were hand-searched. SELECTION CRITERIA: Randomised controlled trials which compared selenium supplementation either parenterally or enterally with placebo or nothing from soon after birth in preterm or very low birthweight infants and which reported clinical outcomes were considered for the review. DATA COLLECTION AND ANALYSIS: Data on selenium supplementation dose, formulation and route of administration; mortality, oxygen requirement at 28 days and 36 weeks post-menstrual age, retinopathy of prematurity, and one or more episodes of sepsis; blood selenium and glutathione peroxidase concentrations at or close to 28 days, were excerpted by both reviewers independently. Data analysis was conducted according to the standards of the Cochrane Neonatal Review Group. MAIN RESULTS: Three eligible trials were identified. Two trials, including one trial with a much larger sample size than the others combined, were from geographical areas with low population selenium concentrations. Meta-analysis of the pooled data showed a significant reduction in the proportion of infants having one or more episodes of sepsis associated with selenium supplementation [summary RR 0.73 (0.57, 0.93); RD -0.10 (-0.17, -0.02); NNT 10 (5.9, 50)]. Supplementation with selenium was not associated with improved survival, a reduction in neonatal chronic lung disease or retinopathy of prematurity. REVIEWER'S CONCLUSIONS: Supplementing very preterm infants with selenium is associated with benefit in terms of a reduction in one or more episodes of sepsis. Supplementation was not associated with improved survival, a reduction in neonatal chronic lung disease or retinopathy of prematurity. Supplemental doses of selenium for infants on parenteral nutrition higher than those currently recommended may be beneficial. The data are dominated by one large trial from a country with low selenium concentrations and may not be readily translated to other populations.

Chronic Disease↗
PubMed1996

Toxicity of seleno-L-methionine, seleno-DL-methionine, high selenium wheat, and selenized yeast to mallard ducklings.

The toxicity of four chemical forms of selenium (seleno-L-methionine, seleno-DL-methionine, selenized yeast, and high selenium wheat) was compared in day-old mallard ducklings (Anas platyrhynchos). In the first experiment, in which the basal diet was 75% wheat, survival after 2 weeks was lower for ducklings fed 30 micrograms/g selenium as seleno-L-methionine (36%) than for ducklings fed 30 micrograms/g selenium as seleno-DL-methionine (100%) or 30 micrograms/g selenium from high selenium yeast (88%). The concentration of selenium at 2 weeks in the livers of survivors was similar for ducklings fed 15 micrograms/g selenium as seleno-DL-methionine (12 micrograms/g, wet weight), seleno-L-methionine (11 micrograms/g), and high selenium wheat (11 micrograms/g), but was lower when the selenium came from selenized yeast (6.2 micrograms/g). When fed 30 micrograms/g selenium from the various sources, the selenium concentrations in liver were 20 micrograms/g for seleno-DL-methionine, 19 micrograms/g for seleno-L-methionine, and 9.9 micrograms/g for selenized yeast. In a second experiment, in which the basal diet was a commercial duck feed, survival after 2 weeks was 100% in ducklings fed 30 micrograms/g selenium as seleno-DL-methionine, seleno-L-methionine, or selenized yeast. Selenium concentrations in liver were similar for ducklings fed the 30-micrograms/g selenium diets as the DL or L forms of selenomethionine (27 and 25 micrograms/g), but lower for ducklings fed selenized yeast (13 micrograms/g).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

[Effect on metabolism of thyroid hormones in deficient to subtoxic selenium supply levels].

In an experiment with 72 male weanling Sprague Dawley rats the effect of varying selenium intake on parameters of thyroid hormone metabolism was investigated. The animals were divided into 6 groups. One of the groups was fed a semi-synthetic diet based on casein which was poor in selenium (38 micrograms/kg). The other groups were fed the same diet supplemented with Na2SO3.5H2O to achieve a selenium concentration of 50, 100, 300, 600 and 3,000 micrograms/kg. The experiment lasted 40 days. Different selenium intake had no effect on food intake, weight gain, hematological and selected clinical-chemical parameters. Determination of glutathione peroxidase activity and selenium concentration of serum showed a selenium deficiency in animals fed the diet not supplemented with selenium. Serum T3 concentration and hepatic type-I-deiodinase activity were decreased in the group without selenium supplementation in contrast to the groups fed diets adequate in selenium (100, 300 micrograms/kg). A diet supplementation of 50 micrograms/kg already increased hepatic type-I-deiodinase activity to levels of the groups fed diets adequate in selenium. In groups supplemented with 600 and 3,000 micrograms/kg diet, serum T3 concentration was reduced by half of groups fed diets adequate in selenium. Supplementation with 3,000 micrograms Se/kg lowered the type-I-deiodinase activity in contrast to groups fed diets adequate in selenium, but not significantly. Serum concentrations of T4 and fT4 were not changed by various selenium intake. The results of this investigation show an alteration in thyroid hormone metabolism at low selenium intake as well as at high selenium intake.

Animals↗
PubMed1998

Bioavailability of enteral yeast-selenium in preterm infants.

There is no data or literature on the effects of supplementing infants with yeast selenium, although its intestinal absorption and bioavailability are higher in adults compared with other selenium compounds. The aim of the present investigation was to study the impact of selenium enriched yeast on the serum selenium concentration of preterm infants living in a low selenium area (Hungary). Twenty-eight preterm infants with mean+/-SD birth weight of 962+/-129 g and gestational age 27+/-1 wk were randomized into two groups at birth with respect to selenium supplementation. In the supplemented group (n=14) infants received 4.8 mg yeast selenium containing 5 microg selenium daily via nasogastric drip during the first 14 postnatal days. The nonsupplemented infants were used as a reference group. In the supplemented group, the serum selenium concentration increased from 32.1+/-8.5 microg/L to 41.5+/-6.5 microg/L and in the nonsupplemented group it decreased from 25.9+/-6.8 microg/L to 18.2+/-6.4 microg/L from birth in two weeks time. Compared with previous studies, our results suggest that the bioavailability of selenium in the form of yeast selenium is higher than that of other selenium compounds used for preterm infants. We did not observe any complications or side-effects owing to enteral yeast selenium supplementation. We conclude that selenium enriched yeast is a safe and an effective form of short-term enteral selenium supplementation for infants.

Biological Availability↗
PubMed1990

Relationship between selenium, immunity and resistance against infection.

1. Food selenium content, selenium supply and selenium needs are presented, along with methods of evaluation of selenium status. Glutathione peroxidase, a selenium-containing enzyme, is ubiquitous in the organism. 2. Some experimental studies on animal models reported a positive relationship between selenium status and resistance against infections. 3. Only one study in humans concerned the mechanisms of immune functions in selenium deficiency. Several experimental works suggest that severe selenium deficiency compromises T-cell dependent immune functions such as the blastogenic response to mitogens, but selenium deficiency was concomitant with vitamin E deficiency in most of them. Delayed hypersensitivity response is controversial in selenium-supplemented rats and guinea-pigs. 4. Selenium deficiency in animals decreases the antibody response, especially if associated with vitamin E deficiency. Low dietary selenium supplementation of healthy animals has a positive effect upon humoral responses. 5. Despite some controversies, most experimental studies on selenium-deficient animals report normal phagocytosis and an altered bactericidal capacity of neutrophils. The decrease in glutathione peroxidase activity of polymorphonuclear cells following selenium deficiency could explain some of these alterations. 6. Splenic Natural Killer cells activity is enhanced in selenium-supplemented, healthy animals.

Animals↗
PubMed2005

Toenail and plasma levels as biomarkers of selenium exposure.

PURPOSE: Both blood and toenail selenium are used to assess selenium exposure in epidemiologic studies. Little is known about the relationship of these biomarkers with each other or about whether there are differences in the relationships of these biomarkers with diet, supplement use, or participant characteristics. METHODS: Data are from 220 participants in a large cohort study of supplement use and cancer risk. Measures of selenium exposure included supplement use (current and 10-year) from a self-administered questionnaire, an inventory of currently used supplements (multivitamins and single supplements), dietary intake from a food frequency questionnaire (FFQ), and selenium concentration in toenails and plasma. RESULTS: Plasma and toenail selenium concentrations were significantly correlated (r=.56 [95% confidence interval: .46, .64]). Supplemental selenium was the strongest predictor of both selenium biomarkers, and these associations were slightly stronger when based on the supplement inventory and 10-year self-reported use compared to current self-reported use. Correlations of current and 10-year questionnaire dose and inventory dose with toenail selenium were .26, .36, and .33; for plasma selenium, these were .27, .36, and .36. Neither dietary selenium nor any participant characteristics, except smoking, was related to either biomarker. Current smokers had lower toenail, but not plasma, selenium levels compared to nonsmokers (.89 versus 1.03 microg/g, p = .03); however, the difference was not significant after control for supplement use (p = .09). CONCLUSIONS: Both toenail and plasma selenium levels similarly reflect selenium intake exposure. There do not appear to be independent associations of toenail or plasma selenium with FFQ-derived selenium intakes, health-related behaviors, or demographic characteristics.

Biomarkers↗