Plasma Se Levels Research Articles

Nutritional bioavailability to rats of selenium in Brazil nuts and mushrooms

Weanling male rats were fed a selentum (Se)-deficient Torula yeast diet for 4 to 9 weeks followed by either continued depletion or repletion for 4 to 6 weeks with Se as sodium selenite, extracted Brazil nut meal, or dried mushroom powder. The Se in the Brazil nut meal ( Bertholletia excelsa) was fully as available as that in sodium selenite when judged by the ability of dietary Se to restore plasma and liver glutathione peroxidase activities or Se levels. By these same criteria, the Se in cultivated commercial mushrooms ( Agaricus bisporus) or wild mushrooms ( Boletus edulis) was of very poor bioavailability. Addition of mushroom powder to a diet containing selenite did not interfere with the ability of the selenite to restore hepatic glutathione peroxidase activity during repletion. These results demonstrate the great differences that can occur in the bioavailability of Se from different foods and point out the need to develop suitable Se bioavailability assays in humans.

Mercury-selenium interaction in workers exposed to elemental mercury vapor.

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

Nutritional availability to rats of selenium in four seafoods: crab (Callinectes sapidus), oyster (Crassostrea virginica), shrimp (Penaeus duorarum) and Baltic herring (Clupea harengus).

1. The present study was conducted to determine the biological availability to rats of the selenium in four high-Se seafoods: crab (Callinectes sapidus), oyster (Crassostrea virginica), shrimp (Penaeus duorarum) and Baltic herring (Clupea harengus). 2. Weanling male rats were fed on a Se-deficient Torula yeast diet for 4 weeks followed by either continued depletion or repletion for 4 weeks with 0.05, 0.1 or 0.2 microgram Se as selenite/g, or 0.1 or 0.2 microgram Se as freeze-dried cooked test food/g. Plasma and liver Se levels or glutathione peroxidase (EC 1.11.1.9; GSH-Px) activities were used as indicators of body Se status. 3. Except for oysters, the biological availability of Se in all these seafoods was close to that of selenite (selenite 100%) when the criterion used was either plasma Se level or plasma GSH-Px activity. 4. By the criterion of increased liver Se level of restored hepatic GSH-Px activity, only herring-Se had a biological availability comparable to that of selenite-Se under all conditions tested, whereas crab-Se and oyster-Se were distinctly inferior in this regard. 5. Increasing the amount of crab-Se, oyster-Se or shrimp-Se supplied in the diet from 0.1 to 0.2 microgram/g changed the apparent availability (%) of Se for hepatic GSH-Px restoration from 38 to 78, 22 to 53 and 57 to 90 respectively. 6. The present study demonstrates that the availability of Se in certain foods is a function of the criterion chosen, the level of Se supplied in the diet, and possibly other unknown interacting dietary factors.

Selenium Depletion in Burn Patients

Victims of major burns may be at risk for selenium (Se) depletion because increased postinjury nutrient needs are often met by total parental nutrition and tube feedings which contain little Se. This study compared Se status of 17 burn patients and 191 healthy control subjects. Se intake of burn patients was lower than the intake of control subjects when total parenteral nutrition or tube feedings were used as primary nutrient sources but was comparable to the control intake when burn patients consumed oral diets. Serial determinations each 10 days during recovery showed that burn patients had lower plasma Se, erythrocyte Se, and erythrocyte glutathione peroxidase levels, and lower 24-hr urine Se excretion. These results provide biochemical evidence of Se depletion despite exogenous Se intake within the range recommended for healthy adults. Further studies are indicated to determine if Se depletion in burn patients can be prevented by Se supplementation of total parenteral nutrition and tube feeding solut...

Bioavailability to rats of selenium in milk of cows fed sodium selenite or selenited barley.

The nutritional availability of Se to rats in two experimental Finnish milks were compared to that in American milk naturally high in Se. The experimental milks had their Se content increased by feeding cows either sodium selenite (selenited milk) or selenited barley (selenited-barley milk). Weanling male rats were fed a low-Se milk powder diet for 4 weeks followed by continued depletion or repletion with graded levels of Se as sodium selenite (standard) or different milks for 4 weeks. Plasma Se level and plasma and liver glutathione peroxidase (GSH-Px) activities were used as criteria of body Se status. The bioavailability of Se was calculated with the slope-ratio method. The Se in the selenited-barley milk was significantly (p less than 0.01) more available than that in the selenited milk when the plasma Se level was the response criterion. On the other hand, the bioavailability of Se from the various milks was not different when plasma or liver GSH-Px activities were used as the response criteria. Overall bioavailability for the selenited milk, selenited-barley milk and American milk was only slightly less than that for the standard (sodium selenite = 1.00), showing that milk is a relatively readily available source of dietary Se.

Selenium status of malnourished hospitalized patients.

We evaluated selenium (Se) status of 44 hospitalized patients with protein-energy malnutrition. The patients were assigned to "normal" or "low" Se groups-1 and 2, respectively-based on whether the plasma Se level exceeded or was below the value of the mean-2SD of healthy Georgians'. Plasma and erythrocyte Se levels correlated significantly (r = .52, P less than .01). Erythrocyte glutathione peroxidase activity was highly correlated with plasma Se (r = .68) in group 2; there was no significant correlation between these parameters in group 1. In group 2 the mean plasma prealbumin level was significantly lower, and the mean corpuscular volume and serum glutamic oxaloacetic transaminase level were significantly higher compared to group 1. Other nutritional parameters did not correlate with Se status. Concomitant deficiencies of other nutrients were common in both patient groups. Se levels may relate to protein status, and abnormal hematologic and hepatic parameters may reflect low Se status and/or protein-energy malnutrition. Low Se status is common in malnourished patients from a low Se area, and Se supplementation should be included in their nutritional-repletion regimens.

Vitamin E and selenium status of patients receiving short-term total parenteral nutrition.

In a prospective protocol, plasma tocopherols, selenium (Se), Se-dependent glutathione peroxidase, platelet aggregation and erythrocyte hemolysis were measured in 23 control subjects, and 15 patients receiving total parenteral nutrition (TPN), before and after 2 wk of TPN unsupplemented with vitamin E and Se. The results indicate that short-term TPN did not alter status of these nutrients. However, TPN patients had significantly lower plasma levels of Se (p less than 0.01) and alpha-tocopherol (p less than 0.01) relative to control subjects. Low plasma levels, with no attendant decrease in function, suggest a marginal depletion. In view of this, and considering the low amount of vitamin E and Se supplied by the TPN solutions, supplementation with these nutrients is recommended.

Effects of riboflavin supplementation and selenium source on selenium metabolism in the young pig.

The effect of dietary riboflavin (B2) supplementation and selenium (Se) source on the performance and Se metabolism of weanling pigs was studied. Pigs fed a B2-supplemented (10 mg/kg) casein-glucose diet for 18 d gained faster than pigs fed the B2-unsupplemented diet. Percentage active erythrocyte glutathione reductase (GR) declined rapidly when pigs were placed on the B2-unsupplemented diet and was lower (P less than .01) than that of B2-supplemented pigs after 12 d on test. Percentage active erythrocyte GR values fell below 50% before other B2 deficiency signs became evident. Supplementation of diets with 10 mg B2/kg resulted in increased kidney and muscle glutathione peroxidase (GSH-Px) activity. The Se concentration of liver and heart increased and plasma Se levels decreased with dietary B2 supplementation. Riboflavin supplementation and Se source did not alter apparent Se absorption, but B2 supplementation decreased urinary Se and thus increased Se retention. Also, there was less urinary Se excretion when selenomethionine was the dietary Se source and consequently more Se was retained than when sodium selenite was the dietary Se source. In a final trial, B2 supplementation increased kidney, muscle, heart and brain GSH-Px activity when sodium selenite was the dietary Se source, but not when selenomethionine was the dietary Se source.

Selenium depletion in burn patients.

Victims of major burns may be at risk for selenium (Se) depletion because increased postinjury nutrient needs are often met by total parental nutrition and tube feedings which contain little Se. This study compared Se status of 17 burn patients and 191 healthy control subjects. Se intake of burn patients was lower than the intake of control subjects when total parenteral nutrition or tube feedings were used as primary nutrient sources but was comparable to the control intake when burn patients consumed oral diets. Serial determinations each 10 days during recovery showed that burn patients had lower plasma Se, erythrocyte Se, and erythrocyte glutathione peroxidase levels, and lower 24-hr urine Se excretion. These results provide biochemical evidence of Se depletion despite exogenous Se intake within the range recommended for healthy adults. Further studies are indicated to determine if Se depletion in burn patients can be prevented by Se supplementation of total parenteral nutrition and tube feeding solutions.

Bioavailability of selenium to Finnish men as assessed by platelet glutathione peroxidase activity and other blood parameters

Three groups of 10 men of low selenium status were given 200 micrograms Se/day as Serich wheat, Se-rich yeast, or sodium selenate for 11 wk. Twenty unsupplemented subjects served as controls. Plasma Se levels increased steadily in the wheat and yeast groups for 11 wk without plateauing, whereas in the selenate group, plasma Se plateaued around 110 ng/ml after 4 wk. Platelet glutathione peroxidase (GSH-Px) activities increased rapidly in the wheat and selenate groups for 4 wk and then plateaued. Platelet GSH-Px increased more slowly in the yeast group. Ten weeks after the supplements were discontinued, platelet GSH-Px was higher in the wheat and yeast groups than in the selenate group. Assessment of Se bioavailability requires a short-term platelet GSH-Px measurement to determine immediate availability, a medium-term plasma Se measurement to estimate retention, and a long-term platelet GSH-Px measurement after supplements are discontinued to determine the covertibility of tissue Se stores to biologically active Se.

The selenium status of Belgian population groups

A moderate level of selenium (Se) was demonstrated in the blood (123 ng/mL), erythrocytes (RBC) (161 ng/mL), and plasma (97 ng/mL) of 110 male and 54 healthy female Belgian adults by using hydride-generation atomic absorption spectrometry. These values agree well with those found in neighboring countries. The study is the first one to report on normal values for these parameters in Belgians.Glutathione peroxidase (GSH-Px) activity has also been assayed. The group in considered nondeficient. Neither the concentration of Se in blood, plasma, or RBC, nor the activity of GSH-Px in the latter, were related to age, sex, blood pressure, or smoking habits. Oral contraception was associated with elevated plasma Se levels as compared to controls (P<0.01).A statistically significant positive relationship existed between the Se concentrations in whole blood or in red blood cells and red blood cell GSH-Px activity (r=0.31,p<0.005).

Clinico-Pathologic Findings in Young Pigs Fed Different Levels of Selenium, Vitamin E and Antioxidant

A randomized, blocked 23 factorial experiment was conducted with 48 young pigs. The treatment factors were: 2 levels of selenium (55 and 115 µg/kg), 2 levels of vitamin E (3 and 53 mg/kg) and 2 levels of the antioxidant feed additive Ethoxyquin (0 and 150 mg/kg). All pigs were kept in single pens and fed ad libitum throughout the experimental period of 9 weeks, i.e. from 3 to 12 weeks of age. Plasma, heart, liver and muscle Se levels as well as whole blood glutathione peroxidase activity (EC 1.11.1.9 GSH-Px) were significantly higher in pigs given a dietary supplement of Se than in pigs given no supplement of Se (P ≤ 0.001). The Se-supplemented pigs showed a tendency to lower mean serum transaminase activity (ASAT and ALAT) than unsupplemented pigs, but the influence was significant (P ≤ 0.05) only for the ALAT activity. Blood vit. E levels were higher for pigs receiving a supplement of vit. E than for unsupplemented pigs (P ≤ 0.001), and so was the resistance of red blood cells against lipid peroxidation (ELP), as expressed by lower ELP values. There were no effects of Ethoxyquin supplementation on the biochemical variables included in the study. The histological examination of heart muscle showed that the score for changes was negatively influenced by both Se and vit. E supplement (P ≤ 0.001) and to some extent also by Ethoxyquin supplement (P ≤ 0.05). The histological picture of m. long dorsi was influenced only by the vit. E supplement (P ≤ 0.01). No histological changes were found in the liver in this study. There were inverse relationships between whole blood GSH-Px defluorescence time and blood Se, and between ELP and whole blood vit. E (P ≤ 0.001).

Comparative Effects of Sodium Selenite and Selenomethionine upon Nutritional Muscular Dystrophy, Selenium-Dependent Glutathione Peroxidase, and Tissue Selenium Concentrations of Turkey Poults

Day-old poults from hens depleted of Se were fed low-Se basal diets (containing corn, soybean meal, and torula yeast but n o added vitamin E) with graded levels of Se supplied by Na2SeO3 or seleno-DL-methionine for 28 and 35 days in Experiments 1 and 2, respectively. Adding .04 ppm Se to the basal diet significantly increased body weight and reduced both the incidence of gizzard myopathy and plasma glutamic-oxaloacetic transaminase (PGOT) activity. Further improvements in these parameters were not obtained with higher levels of supplemental Se. Both plasma Se and Se-dependent glutathione peroxidase (SeGSHpx) were elevated by increasing levels of dietary Se. There were no differences in these parameters due to the Se compound fed. Plasma SeGSHpx was significantly correlated with both dietary and plasma Se levels. Poults fed selenomethionine had significantly higher concentrations of Se in the gizzard, breast muscle, and pancreas, but not in the liver and heart, compared to poults fed Na2SeO3. These studies indicate that the utilization of Se in both Na2SeO3 and selenomethionine is approximately equal in young turkey poults.

465 HEMATOLOGICAL AND BIOCHEMICAL CHANGES IN PREMATURE INFANTS ON 3 COMMERCIAL INFANT FORMULAS

Thirty healthy premature infants with birth weights between 1000g and 1600g were randomly assigned at 1 wk of age to 3 groups to determine the effect of 3 commercial infant formulas (Similac 20, Similac 20 with Iron, Iscmil - each containing 15 I.U. vit. E/liter) on various hematological, biochemical and growth parameters. During their hospital stay weekly determinations were made of hemoglobin (Hb); hematocrit (Hct); reticulocyte count; hydrogen peroxide hemolysis; red cell glutathione peroxidase (GSH-Px) and selenium (Se); plasma GSH-Px and Se; and serum Ca, P, alkaline phosphatase, protein, cholesterol and vit. E levels.Mean weekly rates of declines in Hb and in Hct, respectively, did not differ significantly in the 3 groups of infants. Among the infants with the highest rates of declines in Hct and Hb were some with persistently low serum vit. E levels; these were noted in all groups. Red cell and plasma GSH-Px and Se levels did not correlate with the rate of decline in Hb or Hct levels, nor was there a direct and constant correlation between hydrogen peroxide hemolysis and the rate of Hb decline. A decline in serum phosphorus levels was noted in all 3 groups, but was significantly greater (p<.01) in the Isomil group. Under the conditions of our study, iron at the concentration used in Similac with Iron (12 mg/L) did not appear to accelerate hemolysis. Individual variability in the hematological responses was noted irrespective of the formula used.