Essentiality of selenium in the human body: relationship with different diseases

Dietary diphenyl diselenide reduces the STZ-induced toxicity

Oxidative stress is implicated in the pathogenesis of diabetes mellitus. Selenium supplementation has some benefits in experimental models of diabetes mellitus. This study evaluated whether dietary diphenyl diselenide, a simple synthetic organoselenium compound with antioxidant properties, reduces the streptozotocin (STZ)-induced toxicity. STZ-induced diabetic rats were fed with either standard and diphenyl diselenide (10 ppm) supplemented diets. In experimental trials, dietary diphenyl diselenide significantly decreased mortality rate (p<0.05) induced by STZ treatment. No correlation between this effect and glycemic levels were found. Diphenyl diselenide intake also promoted an increase in vitamin C, -SH levels (liver, kidney and blood) and in catalase (liver and kidney) activity, which were decreased in STZ-treated rats. In enzyme assays, diphenyl diselenide supplementation caused a significant improvement in platelets NTPDase and 5'-nucleotidase activities in STZ-induced diabetic rats when compared to the control and diabetic groups (p<0.05). Nevertheless, this supplementation did not modify the inhibition induced by STZ in delta-ALA-D activity. Our findings suggest that diphenyl diselenide compound showed beneficial effects against the development of diabetes by exhibiting antioxidant properties.

Diphenyl diselenide supplementation delays the development of N-nitroso-N-methylurea-induced mammary tumors

The effect of dietary diphenyl diselenide (1 ppm) on N-nitroso-N-methylurea (NMU)-induced mammary carcinogenesis was examined in female Wistar rats. Beginning at 5 weeks of age, the animals were fed with either control or diphenyl-diselenide-supplied diets until the end of the study (210 days). At 50 days of age, mammary tumor was induced by the administration of three doses of NMU (50 mg/kg body wt, intraperitoneally) once a week for 3 weeks. In experimental trials, latency to tumor onset was extended in rats fed with diet supplemented with diphenyl diselenide (P < 0.05). The incidence and frequency of tumors were significantly small in animals supplemented with diphenyl diselenide. However, the multiplicity of tumors was not altered by dietary diphenyl diselenide. Diphenyl diselenide supplementation also restored superoxide dismutase (SOD) activity and vitamin C levels altered in the NMU group (P < 0.05). Our results suggest that diphenyl diselenide can be considered a chemopreventive agent, even when supplemented at a relatively low concentration.

Selenium level in the environment and the population of Zhoukoudian area, Beijing, China

The objective of this study was to detect the selenium level in the environment and the population of Zhoukoudian area, Beijing, and to discuss the influence of various factors on serum selenium level. The soil, drinking water, and foodstuff samples and venous blood samples of 401 individuals were obtained to determine the selenium level by gas chromatograph equipped with a (63)Ni electron capture detector (ECD). The selenium level was 0.210+/-0.013 microg/g in soil, 0.017 microg/L+/-0.002 in drinking water, 0.034+/-0.002 microg/g in rice, and 0.034+/-0.012 microg/g in wheat flour. This index showed that the Zhoukoudian area of Beijing was a moderate or marginal level selenium ecological landscape. The mean serum selenium level of the population was 75.01+/-28.35 microg/L, ranging between 35.2 and 160.4 microg/L. A total of 279 (69.6%) individuals exhibited serum selenium level below 80 microg/L, which is the lowest threshold for the activity of glutathione peroxidases (GPx) in vivo. A total of 35 (8.5%) individuals exhibited serum selenium level below 45 microg/L. It is widely recommended that below this value (45 microg/L) there is an increased risk of cardiovascular disease and cancer. Multiple linear regression analysis showed that serum selenium level was positively associated with body mass index (beta=0.137; P=0.011), serum total cholesterol TC (beta=0.785; P=0.000), however, negatively associated with systolic blood pressure (beta=-0.172; P=0.023), serum triglyceride (beta=-0.170; P=0.007), high density lipoprotein-cholesterol (beta=-0.121; P=0.027), and low high density lipoprotein-cholesterol (beta=-0.568; P=0.027).

Vicia root-mirconucleus and sister chromatid exchange assays on the genotoxicity of selenium compounds

Selenium (Se) is an important metalloid with industrial, environmental, biological and toxicological significance. Excessive selenium in soil and water may contribute to environmental selenium pollution, and affect plant growth and human health. By using Vicia faba micronucleus (MN) and sister chromatid exchange (SCE) tests, possible genotoxicity of sodium selenite and sodium biselenite was evaluated in this study. The results showed that sodium selenite, at concentrations from 0.01 to 10.0mg/L, induced a 1.9-3.9-fold increase in MN frequency and a 1.5-1.6-fold increase in SCE frequency, with a statistically significantly difference from the control (P<0.05 and 0.01, respectively). Sodium selenite also caused mitotic delay and a 15-80% decrease in mitotic indices (MI), but at the lowest concentration (0.005mg/L), it slightly stimulated mitotic activity. Similarly, the frequencies of MN and SCE also increased significantly in sodium biselenite treated samples, with MI decline only at relatively higher effective concentrations. Results of the present study suggest that selenite is genotoxic to V. faba root cells and may be a genotoxic risk to human health.

A strategy for controlling potential interactions between natural health products and chemotherapy: a review in pediatric oncology

The high prevalence of complementary and alternative medicine use including natural health products (NHPs) in the pediatric oncology population is well established. The potential for concurrent use of NHPs with conventional chemotherapy necessitates physician awareness regarding the potential risks and benefits that might come from this coadministration. Knowledge of interactions between NHPs and chemotherapy is poorly characterized; however, an understanding of potential mechanisms of interaction by researchers and clinicians is important. Concerns regarding the use of antioxidants during chemotherapy are controversial and evidence exists to support both adherents and detractors in this debate. Our review addresses issues regarding potential interactions between NHPs and chemotherapies used in pediatric oncology from a pharmacokinetic and pharmacodynamic perspective. Examples of combinations of NHP and chemotherapies are briefly presented in addition to a strategy to avoid (or induce) a possible interaction between a NHP and chemotherapy. In conclusion, more clinical research is needed to substantiate or preclude the use of NHPs in the treatment of cancer and especially in combination with chemotherapy.

Evaluation of colon cancer elements contents in serum using statistical methods

Classification of normal and different cancer groups (TNM classification) with univariate and multivariate statistical methods according to the contents of Cu, Fe, Mn, Se, and Zn in blood serum is discussed. All serum samples were digested by acid mixture in a microwave mineralization unit prior to the analysis by atomic absorption spectrometry. Results show that univariate methods can distinguish normal and cancer groups. Level of selenium evaluated as arithmetic mean with its standard deviation in colorectal cancer patients was (42.61 ± 23.76) µg L−1. Retransformed mean was used to evaluate levels of managanese (11.99 ± 1.71) µg L−1, copper (1.05 ± 0.06) mg L−1, zinc (2.14 ± 0.21) mg L−1, and iron (1.82 ± 0.22) mg L−1. Conclusions of multivariate statistical procedures (principal component analysis, hierarchical, and k-means clustering) do not correlate very well with the division of serum samples according to the TNM classification.

Diphenyl diselenide reduces temporarily hyperglycemia: Possible relationship with oxidative stress

This study was designed to determine the effect of diphenyl diselenide and ebselen, synthetic organoselenium compounds with antioxidant properties, in diabetic rats. Diabetes was induced by the administration of streptozotocin (STZ) (45mg/kg, intravenous). In experimental trials, diphenyl diselenide, but not ebselen, caused a significant reduction in blood glucose levels of STZ-treated rats. This effect of diphenyl diselenide was accompanied by a reduction in the levels of glycated proteins. Diphenyl diselenide ameliorate superoxide dismutase activity (liver and erythrocytes) and Vitamin C levels (liver, kidney and blood), which were decreased in STZ-treated rats. In normal rats, diphenyl diselenide caused per se an increase in hepatic, renal and blood GSH levels. Similarly, treatment with diphenyl diselenide restored hepatic and renal GSH levels in STZ-treated rats. TBARS and protein carbonyl levels were not modified by STZ and/or diphenyl diselenide and ebselen treatments. Our findings suggest that diphenyl diselenide can be considered an anti-diabetogenic agent by exhibiting anti-hyperglycemic and antioxidant properties.

Low contribution of rice and vegetables to the daily intake of selenium in Japan

The growing interest in the prevention role of selenium in certain degenerative diseases such as cancer and cardiovascular disease has fostered research on natural sources of selenium. In this research, total selenium concentrations in over 120 items of selected Japanese foods were determined. The selenium concentration was measured fluorometrically by measurement of the fluorescence of piazselenol resulting from the reaction of selenite with 2, 3-diaminonaphtalene. The selenium level in rice, which is the staple food consumed in Japan, is lower than the other countries. But the mean levels of selenium in meat and fish products are among the highest values reported in other countries. Although the numbers of samples of selected foods analyzed are small, the results describe the picture of the selenium level of Japanese foods.

In vitro effects of vitamin C and selenium on NK activity of patients with beta-thalassemia major

In this study, the in vitro effects of vitamin C and selenium on natural killer (NK) cell activity of ss-thalassemia major patients was investigated. At first, significant decreased NK activity was found at E:T ratios of 1:1, 5:1, and 10:1 in whole thalassemia patients. Low-dose selenium treatment enhanced NK activity in patients but there was no change in the control group. High-dose selenium decreased NK activity significantly in splenectomized patients. Different doses vitamin C enhanced NK activity significantly in both splenectomized and unsplenectomized patients. According to these results, selenium dosage should be arranged carefully in thalassemia patients, whereas vitamin C can be used confidently.

Determination of selenium in sediment by isotope-dilution inductively coupled plasma mass spectrometry with an octapole reaction cell

A method is described for determination of selenium in sediment by isotope-dilution inductively coupled plasma mass spectrometry with an octapole reaction cell (ID-ICP-ORCMS). Sediment samples were digested with HNO3, HClO4, and HF, and the digestion included an elaborate evaporation process to remove bromine from the digested solution. Simple strong cation-exchange disk filtration was used to remove rare earth elements (REE) from the digested solution, because REE2+ seriously interfere with Se isotopes (i.e. 156Gd2+ with 78Se+, 160Gd2+ with 80Se+). Addition of acetic acid to the filtrate was examined to improve the sensitivity of ICP-ORCMS measurement of Se+ by means of a carbon-enhancement effect. The interfering Ar2+ for selenium isotopes were almost eliminated by use of H2 as reaction gas. Interference from BrH+ formed in the reaction cell was negligible because the Br was removed in the evaporation process. Approximately 99.5% of REE were removed by cation-exchange disk filtration yet more than 99% of Se remained in the filtrate solution. The intensity for Se+ was enhanced approximately fourfold by addition of 5% (v/v) of acetic acid whereas that for Ar2+ was barely enhanced. Measured 80Se/78Se ratios in unspiked digested solutions of the sample were in good agreement with that for an Se standard solution. The analytical results for Se in the certified reference materials MESS-3 and PACS-1 were in good agreement with their certified values, with small uncertainties.

Food Intake and Serum Selenium Concentration in Elderly People

BACKGROUND/AIMS

It is becoming apparent that the essential trace element selenium plays a critical role in the maintenance of optimal health status. The objective of this study was to identify the food groups that most contributed to selenium intake and its serum levels in elderly people.

METHODS

Dietary intake was assessed in 205 institutionalized elderly by means of a 1-year food frequency questionnaire (FFQ). Intake of macronutrients and minerals of the diet were estimated. Selenium was determined in serum and analyzed by graphite-furnace atomic absorption spectrometry.

RESULTS

Selenium intake and serum concentration were both within the normal range. The major contributors to selenium intake were cereals and bakery, fish and shellfish, meat and meat products and dairy products. All of them except cereals were also associated to serum selenium. Intake of animal protein, but not the vegetable one, contributed to serum selenium.

CONCLUSION

An adequate intake of fish and meat would be of importance to improve selenium status and health principally in elderly people who are at high risk of mineral deficiency.

Inhibition by Selenium Compounds of Catecholamine Secretion Due to Inhibition of Ca2+ Influx in Cultured Bovine Adrenal Chromaffin Cells

Selenium is an essential trace metal element, whereas large doses of selenium exert adverse effects to the human body. We examined the effects of selenium compounds, sodium selenite (Na2SeO3) and sodium selenate (Na2SeO4), on catecholamine secretion from cultured bovine adrenal chromaffin cells. Treatment of chromaffin cells with sodium selenite for 72, 48, and 24 h caused decreases in protein and catecholamine contents, in association with cell damage, at concentrations over 30, 300, and 300 microM, respectively. The cells treated with subtoxic conditions (<100 microM, 48 h) of sodium selenite were used for further experiments. Sodium selenite treatment for 48 h inhibited carbachol (CCh)-induced catecholamine secretion in a concentration-dependent and non-competitive manner, while it did not affect high K+- and veratridine-induced catecholamine secretion. Sodium selenite (100 microM) did not affect CCh- and veratridine-induced 22Na+ influx, while the compound inhibited 45Ca2+ influx induced only by CCh, but not high K+ and veratridine. Sodium selenate even at higher concentrations (1000 microM) did not affect any stimulus-induced catecholamine secretion and 45Ca2+ influx. Thus, sodium selenite may specifically exert adverse effects, such as inhibition of physiological stimulus-induced catecholamine secretion from adrenal chromaffin cells due to inhibition of Ca2+ influx.

Mercury and selenium concentrations in fish samples from Cachoeira do PiriáMunicipality, ParáState, Brazil

Mercury is a major public health concern because of its widespread occurrence in the environment and its toxic effects on humans, mainly through fish ingestion. On the other hand, selenium is known by its antioxidant effect. For this reason, the knowledge of the correlation between mercury and selenium concentrations in fish samples can bring important information allowing a better understanding of mercury equilibrium in the inhabitants of the Amazon region. In this paper, total mercury and selenium levels were measured in carnivorous (47), omnivorous (44), and herbivorous (4) fish species caught in rivers and in an artificial lake in Cachoeira do PiriáMunicipality, situated in ParáState, Amazon region. The mercury concentration ranged from 1.15 to 13.44 nmol g(-1) and selenium from 2.44 to 14.56 nmol g(-1) for carnivorous species. For noncarnivorous species, mercury concentration ranged from 0.08 to 2.03 nmol g(-1) and selenium from 1.27 to 15.32 nmol g(-1). The molar ratios between mercury and selenium contents obtained for carnivorous and noncarnivorous species were 0.65 and 0.14, respectively. Mercury and selenium levels were positively correlated with fish body mass (weight) only for Hoplias malabaricus (n=35, R2=0.565, P<0.005 and R2=0.608, P<0.005, respectively). Selenium and mercury concentrations were statistically positively correlated only for H. malabaricus (n=35, R2=0.787, P=0.005) and Leporinus sp. (n=38, R2=0.485, P<0.005) known locally as Traíra (carnivorous) and Aracu (omnivorous), respectively.

Better osteoblast adhesion on nanoparticulate selenium— A promising orthopedic implant material

Apart from problems such as poor osseointegration, stress shielding, and wear debris-associated bone cell death, a major concern of metallic orthopedic implants is that they slowly corrode under in vivo environments. It is possible that continuous tissue exposure to metallic corrosion products limits orthopedic implant efficacy; this is especially true for patients receiving implants due to bone cancer. To date, there is no metallic orthopedic implant available in the market that specifically deals with the prevention and/or recurring cancer that may happen in these patients. The objective of this study was to deal with these problems in an integrated way by introducing a new biomaterial to the orthopedic community with anticancer chemistry: selenium (Se). In this study, six types of Se compacts were tested for bone cell (osteoblast) adhesion under in vitro conditions. Two types of cylindrical compacts were made with conventional Se metal particles in the micron (6.539 +/- 1.364-microm diameter) and submicron (0.963 +/- 0.139-microm diameter) range. These two types of compacts were chemically etched with different concentrations of NaOH to create two additional types of Se particles in each category: conventional size particles with nanosurface roughness and nanometer particles (0.204- to 0.264-microm diameter). Results showed for the first time, enhanced osteoblast adhesion on particulate surfaces of the compacts made from conventional Se compared with reference nonparticulate wrought titanium sheets. More importantly, this study provided the first evidence that osteoblast density was further increased on the surfaces of the Se compacts with nanometer particles. These initial findings indicate that there may be a promising future for nanoparticulate Se as an anticancer biocompatible orthopedic material.

Lack of oxidative stress in a selenium deficient area in Ivory Coast--potential nutritional antioxidant role of crude palm oil

BACKGROUND

Previous studies have described an important selenium deficiency in a mountain region (Glanle) in the west of Ivory Coast.

AIM OF THE STUDY

To assess the antioxidant capacity of subjects from a selenium deficient area in Ivory Coast (Glanle region).

METHODS

This study involved 57 subjects, 18 to 69 years old, living in the Glanle region and 56 healthy controls living in the southern coastal region (Bodou). In the Glanle region families consume basically a vegetarian and crude palm oil diet, whereas in the Bodou region, families eat a fish-based diet with principally refined palm oil. Fasting blood samples were collected to assess the following parameters: lipid status (plasma total lipids; total-, HDL and LDL-cholesterol; triglycerides; phospholipids; fatty acid composition), plasma protein status (total protein, albumin, transthyretin, orosomucoid, CRP, transferrin), antioxidant capacity (plasma selenium, uric acid, retinol, alpha-tocopherol and tocotrienols levels, plasma seleno-glutathione peroxidase (GSHPx) activity) and oxidative stress markers (malondialdehyde (MDA) and advanced oxidation protein products (AOPP)).

RESULTS

The mountain region samples (Glanle) were characterized by significantly lower plasma albumin, total-, HDL- and LDL-cholesterol, retinol and selenium levels, plasma PUFA content and GSHPx activity, but significantly higher alpha-tocopherol index and total tocotrienol level, than controls from the coastal area (Bodou). These results suggest a higher exposure risk to oxidative stress for the mountain region subjects. However, the absence of oxidative damage in this group provides evidence of a selenium independent protection mechanism against oxidative stress. This protection is related to lower plasma LDL cholesterol and PUFA content, and to higher alpha-tocopherol index, delta and total tocotrienols.

CONCLUSION

The long-term consumption of crude palm oil could be considered as an effective protective factor against oxidative stress.

Chemoprevention of prostate cancer with selenium: an update on current clinical trials and preclinical findings

Prostate cancer is the most common cancer diagnosed and the second leading cause of cancer-related deaths in men in the United States. The etiological factors that give rise to prostate cancer are not known. Therefore, it is not possible to develop primary intervention strategies to remove the causative agents from the environment. However, secondary intervention strategies with selenium (Se) compounds and other agents represent a viable option to reduce the morbidity and mortality of prostate cancer. In this review, we discuss ongoing clinical trials. In addition, we discuss preclinical mechanistic studies that provide insights into the biochemical and molecular basis for the anti-carcinogenic activity of both inorganic and organic forms of Se.

Effect of insulin-like growth factor-I on nitrogen balance and intestinal galactose transport in rats with moderate liver cirrhosis

The malnutrition caused by liver cirrhosis (LC) often worsens the course of the disease. Patients affected by LC often have a low bioavailability of the anabolic liver peptide insulin-like growth factor (IGF)-I. The present study was undertaken to investigate the effect of low doses of IGF-I on the nutritional status and in vivo jejunal transport of D-galactose in anatomically, pathologically and biochemically confirmed moderate, non-ascitic, cirrhotic rats. LC was experimentally induced in growing rats by inhalation of CCl4 and addition of phenobarbital to drinking water. Both the nutritional status, as evaluated by N balance, and in vivo intestinal transport of D-galactose, were significantly impaired in cirrhotic rats. As compared with healthy rats, administration of 20 microg human recombinant IGF-I/kg body weight for 14 d to cirrhotic rats significantly improved N balance variables and restored in vivo intestinal transport of the sugar. However, IGF-I had no effect on the steatorrhoea associated with LC. These results suggest that low doses of IGF-I may have beneficial effects on the malnutrition associated with moderate LC.

Effects of dietary selenium on glutathione peroxidase and thioredoxin reductase activity and recovery from cardiac ischemia-reperfusion

Glutathione peroxidase and thioredoxin reductase are selenocysteine-dependent enzymes that protect against oxidative injury. This study examined the effects of dietary selenium on the activity of these two enzymes in rats, and investigated the ability of selenium to modulate myocardial function post ischemia-reperfusion. Male wistar rats were fed diets containing 0, 50, 240 and 1000 microg/kg sodium selenite for 5 weeks. Langendorff perfused hearts isolated from these rats were subjected to 22.5 min global ischemia and 45 min reperfusion, with functional recovery assessed. Liver samples were collected at the time of sacrifice, and heart and liver tissues assayed for thioredoxin reductase and glutathione peroxidase activity. Selenium deficiency reduced the activity of both glutathione peroxidase and thioredoxin reductase systemically. Hearts from selenium deficient animals were more susceptible to ischemia-reperfusion injury when compared to normal controls (38% recovery of rate pressure product (RPP) vs. 47% recovery of RPP). Selenium supplementation increased the endogenous activity of thioredoxin reductase and glutathione peroxidase and resulted in improved recovery of cardiac function post ischemia reperfusion (57% recovery of RPP). Endogenous activity of glutathione peroxidase and thioredoxin reductase is dependent on an adequate supply of the micronutrient selenium. Reduced activity of these antioxidant enzymes is associated with significant reductions in myocardial function post ischemia-reperfusion.

Free radical scavenging efficiency of Nano-Se in vitro

In this study, we showed that smaller size particles of Nano-Se have better scavenging effects on the following free radicals: carbon-centered free radicals (R*) generated from 2,2'-azo-bis-(2-amidinopropane) hydrochloride (AAPH), the relatively stable free radical 1,1-diphenyl-2-picryhydrazyl (DPPH), the superoxide anion (O2*-) generated from the xanthine/xanthine oxidase (X/XO) system, singlet oxygen (1O2) generated by irradiated hemoporphyrin. Furthermore, the three sizes of Nano-Se studied also show protective effects against the oxidation of DNA. The three samples all have potential size-dependent characteristics on scavenging the free radicals. Although in this study we regarded Nano-Se as a whole without considering interactions between BSA and the red selenium nano-particles, there is the possibility that the apparent free radical scavenging effects may be partially contributed by such interactions.

Influence of dietary selenium supplementation and exercise on thiol-containing enzymes in mice

OBJECTIVE

Exercise markedly increases oxygen uptake by active muscles and consequently increases generation of reactive oxygen species. A dietary deficiency in selenium (Se) can increase the sensitivity of the living system to oxidative stress. delta-Aminolevulinate dehydratase (delta-ALA-D), succinate dehydrogenase (SDH), and lactate dehydrogenase (LDH) are sulfhydryl-containing enzymes, and their activities are sensitive to the presence of oxidizing agents. We investigated the effect of Se deficiency and supplementation on delta-ALA-D, SDH, and LDH activities in mice subjected to swim training for 8 wk.

METHODS

Three-month-old female mice were randomly assigned and fed a basal diet, a basal diet plus 1 ppm of Se, and a basal diet plus 40 ppm of Se. These groups were further divided into sedentary and swim-trained groups. A mass equivalent of 5% of the animal's body weight was fixed to the tail. Animals were then exercised for 60 min/d, 4 d/wk.

RESULTS

Swim-training associated with Se-deficient diet diminished delta-ALA-D activity in the livers and kidneys. SDH activity was diminished in the skeletal and cardiac muscles of this group.

CONCLUSIONS

These results indicated that exercise associated with dietary Se deficiency can inhibit the production of thiol-containing enzymes, delta-ALA-D and SDH, from different tissues; however, LDH activity was not changed. The decrease in enzyme activities can be tentatively attributed to oxidation of thiol groups by the reactive oxygen species produced by exercise.

Selenium concentrations in serum of individuals with liver diseases (cirrhosis or hepatitis): relationship with some nutritional and biochemical markers

Serum concentrations were measured in individuals (n = 50) with liver diseases (cirrhosis and hepatitis) by hydride generation atomic absorption spectrometry in a cross-sectional study. Mean serum selenium levels determined in patients with cirrhosis (n = 12) or with hepatitis (n = 38) were significantly lower (P<0.01) than those measured in control groups mainly due to a decreased liver function. Mean serum selenium concentrations were significantly lower in cirrhotic individuals when compared with patients with hepatitis (P<0.05). Therefore, the severity of the live injury is a factor conditioning the impairment in the selenium body status observed in individuals with hepatopathies. In hepatic patients serum total cholesterol levels showed a significant correlation with serum selenium concentrations (r=0.912, P<0.05) demonstrating the important role of selenium as an antioxidant agent; similarly, gamma-glutamic-transferase levels were significantly correlated with the serum selenium levels (r=-0.803, P<0.05) indicating that when the intensity of the hepatic injury increases (enhancement in serum GGT levels) concomitantly the serum selenium levels decrease significantly. No significant relationships between serum selenium levels and sex or age of patients were observed.

Selenium intakes in 18-64-y-old Irish adults

OBJECTIVE

To measure the intake of selenium (Se) and the contribution of different food groups to Se intake in adults aged 18-64 y in Ireland. The adequacy of Se intake in the population is also assessed.

DESIGN

Food consumption was estimated using a 7 day food diary for a representative sample (n=1379; men=662, women=717) of 18-64-y-old Irish adults selected randomly from the electoral register. Se intake was estimated using updated tables of food composition.

RESULTS

Mean daily Se intakes (+/-s.d.) from all sources (ie food plus supplements), and from food sources alone, for the group of Irish adults aged 18-64 y were 52 (+/-23) and 50 (+/-21) microg, respectively. Mean daily Se intake (from all sources) was significantly higher in men of all ages than women of all ages at levels of 60 and 44 microg, respectively (P<0.001). Meat/meat products (30%), bread and rolls (24%), fish/fish products (approximately 11%), and milk and yoghurt (9%) were the main contributors to mean daily Se intake. Adequacy of Se intake in population groups was estimated as the percentage of the population with mean daily Se intakes that were lower than the average requirement of 40 microg. Using this measure, 45.6% of women and 17.1% of men had inadequate Se intakes.

CONCLUSION

A significant prevalence of inadequate Se intakes was observed in Irish adults. Therefore, it would seem prudent that the Se status of the Irish population be investigated at this time.

Selenium status of Irish adults: evidence of insufficiency

BACKGROUND

Sub-optimal selenium status may have a role in the aetiology of various pathologies. Selenium status depends on adequate selenium in the diet. A relatively high proportion of Irish adults (17% men; 46% women) have an inadequate dietary intake.

AIM

A study was designed to examine the selenium status of healthy Irish adults.

METHODS

Ninety-one healthy Irish adults, aged 18-67 years, were recruited from the Cork City area. A fasting blood sample was collected from each subject and each was assayed for serum selenium an index of serum selenium.

RESULTS

Mean (+/- SD) serum selenium concentration in healthy Irish adults was 76 (+/- 21)microg/l. There was no significant difference in values between males and females or between postmenopausal and premenopausal women or between the three main age categories.

CONCLUSION

Current serum selenium values of Irish adults would not appear to be sufficient to achieve optimal activity of glutathione peroxidase, which occurs at serum selenium concentration around 95microg/l. Sub-optimal selenium status may increase susceptibility to various chronic disorders.

Daily intake of Se by adult population of Mumbai, India

The atmospheric Se levels in Mumbai varied between 0.02 and 1.92 ng m(-3) with a mean concentration of 0.21 ng m(-3). The daily intake of Se by the adult population of Mumbai is 61.9 microg day(-1). Differential pulse cathodic stripping voltammetry (DP-CSV) has been used for the determination of Se in air particulate and food samples. The detection limit of Se using DPCSV was found to be 0.05 ng ml(-1). The reliability of estimation was further assessed through the analysis of standard reference materials (SRMs), tuna fish, animal blood, milk powder and fish tissue obtained from IAEA. The frequency distribution of dietary intake levels of selenium for Mumbai adults showed that approximately 61% of the studied population have a dietary intake of 30-90 microg day(-1). Ingestion was found to be the main route of Se exposure for Mumbai adults. The turn over time of Se through blood is 17 days.

Glutathione peroxidase and viral replication: implications for viral evolution and chemoprevention

It is likely that several of the biological effects of selenium are due to its effects on selenoprotein activity. While the effects of the anti-oxidant selenoprotein glutathione peroxidase (GPx) on inhibiting HIV activation have been well documented, it is clear that increased expression of this enzyme can stimulate the replication and subsequent appearance of cytopathic effects associated with an acutely spreading HIV infection. The effects of GPx on both phases of the viral life cycle are likely mediated via its influence on signaling molecules that use reactive oxygen species, and similar influences on signaling pathways may account for some of the anti-cancer effects of selenium. Similarly, selenium can alter mutagenesis rates in both viral genomes and the DNA of mammalian cells exposed to carcinogens. Comparisons between the effects of selenium and selenoproteins on viral infections and carcinogenesis may yield new insights into the mechanisms of action of this element.