***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Intervention trials with different forms of selenium are under way to assess the effects of selenium supplements on the incidence of cancer and other diseases . Plasma selenium biomarkers respond to selenium administration and might be useful for assessing compliance and safety in these trials . The present study characterized the effects of selenium supplementation on plasma selenium biomarkers and urinary selenium excretion in selenium-replete subjects .  Moderate ( ∼200 μg/d ) to large ( ∼600 μg/d ) selenium supplements in the forms sodium selenite , high-selenium yeast ( yeast ) , and l-selenomethionine ( selenomethionine ) were administered . Subjects were r and omized into 10 groups  ( placebo and three dose levels of each form of selenium ) . Plasma biomarkers ( selenium concentration , selenoprotein P concentration , and glutathione peroxidase activity ) were determined before supplementation and every 4 weeks for 16 weeks . Urinary selenium excretion was determined at 16 weeks . Supplementation with selenomethionine and yeast raised the plasma selenium concentration in a dose-dependent manner . Selenite did not . The increased selenium concentration correlated with the amount of selenomethionine administered . Neither glutathione peroxidase activity nor selenoprotein P concentration responded to selenium supplementation . Urinary selenium excretion was greater after selenomethionine than after selenite , with excretion after yeast being intermediate and not significantly different from either of the other two . We conclude that plasma selenium concentration is useful in monitoring compliance and safety of selenium supplementation as selenomethionine but not as selenite . Plasma selenium seems to reflect the selenomethionine content of yeast but not the other yeast selenium forms . As judged by urinary selenium excretion , selenium in the form of selenomethionine is better absorbed than selenite . ( Cancer Epidemiol Biomarkers Prev 2006;15(4):804–10 BACKGROUND Little is known about the long-term effects of garlic or micronutrient supplementation on total , HDL , and LDL cholesterol in disease-free persons . OBJECTIVE We aim ed to assess the effects of long-term supplementation with garlic and micronutrients and of short-term amoxicillin and omeprazole treatment on serum total , HDL , and LDL cholesterol in a rural Chinese population . DESIGN We conducted a r and omized , double-blind , placebo-controlled , 2 x 2 x 2 and 2 x 2 factorial study of precancerous gastric lesions in 3411 subjects in Linqu County , Sh and ong Province , China . Thirty-four subjects were r and omly selected from each of 12 treatment strata . Sera were analyzed at 3.3 and 7.3 y to measure effects on total , HDL , and LDL cholesterol after 2-wk twice-daily treatment with 1 g amoxicillin and 20 mg omeprazole and supplementation throughout the study with 1 ) 2 capsules twice daily , each containing 200 mg aged garlic extract and 1 mg steam-distilled garlic oil , or 2 ) twice-daily micronutrient capsules containing 250 mg vitamin C , 100 IU vitamin E , and 37.5 mg selenium . RESULTS Regressions adjusted for covariates indicated increases of 0.22 mmol total cholesterol/L ( P = 0.01 ) and 0.19 mmol LDL/L ( P = 0.02 ) after 7.3 y of micronutrient supplementation , but no effect of garlic supplementation or short-term amoxicillin and omeprazole treatment . CONCLUSIONS In this rural Chinese population with low meat intake and moderate cholesterol concentrations , long-term garlic supplementation had no effect on lipid profiles , whereas micronutrient supplementation was associated with small but significant increases in total and LDL-cholesterol concentrations at 7.3 Antioxidant micronutrients have been reported to be associated with an improvement in the blood profile , but the results are not consistent . The aim of the present study was to assess the effects of antioxidant supplementation on changes in the serum lipid profile of adult participants in the SU.VI.MAX study . French adults ( n=12,741∶7,713 females aged 35–60 yr , and 5,028 males aged 45–60 yr ) received daily antioxidant supplementation ( 120 mg vitamin C , 30 mg vitamin E , 6 mg β-carotene , 100 μg selenium , and 20 mg zinc ) or a matching placebo . Median follow-up time was 7.5 yr . After 7.5 yr , no effect of supplementation on total cholesterol was observed in men or women after adjusting for baseline total cholesterol levels and lipid-lowering medications . The prevalence of hypercholesterolemia ( ≥6.5 mmol/L ) showed a trend toward being higher in women who received supplements compared with those who received the placebo ( P=0.06 ) . In both sexes , the group receiving supplements exhibited higher mean serum TG concentrations than did the placebo group ( P=0.06 in men ; P=0.05 in women ) . The prevalence of hypertriglyceridemia ( ≥2.3 mmol/L ) was also significantly higher in men who received supplements ( P=0.03 ) , but not in women . Our results suggest than long-term daily supplementation with low doses of β-carotene , vitamins C and E , selenium , and zinc does not result in an improved lipid profile and could even adversely affect some blood lipids , possibly with a higher risk of hyperlipidemia in women BACKGROUND Observational data suggest a protective effect of several antioxidants on  fasting plasma glucose ( FPG ) and type 2 diabetes .  However , r and omized trials have yielded inconsistent results . OBJECTIVES The first objective was to assess the effect of 7.5 y of antioxidant supplementation on FPG at 7.5 y. The second objective was to examine the epidemiologic association of baseline dietary intakes or plasma antioxidants and FPG ( at baseline and at 7.5 y ) . DESIGN Subjects ( n = 3146 ) from the Supplementation en Vitamines et Minéraux Antioxydants ( SU.VI.MAX ) primary prevention trial in France were r and omly assigned to receive a daily capsule containing 120 mg vitamin C , 30 mg vitamin E , 6 mg beta-carotene , 100 mug Se , and 20 mg Zn or a placebo . RESULTS After 7.5 y , no significant difference was observed between age-adjusted  mean FPG  in men ( P = 0.78 ) and women ( P = 0.89 ) in either group . Baseline beta-carotene dietary intakes and plasma concentrations were inversely associated with FPG in multivariate mixed models ( P = 0.0045 and P < 0.0001 , respectively ) . Baseline plasma vitamin C and selenium were negatively ( P = 0.0455 ) and positively ( P < 0.0001 ) associated , respectively , with FPG . CONCLUSIONS Supplementation with antioxidants at nutritional doses for 7.5 y had no effect on  FPG in men or women who followed a balanced diet . An inverse association of baseline beta-carotene dietary intake and plasma concentrations with FPG was found , probably because beta-carotene is an indirect marker of fruit and vegetable intakes BACKGROUND We previously reported an inverse association between prediagnostic serum selenium concentrations and the risk of  esophageal squamous cell carcinoma ( ESCC ) and gastric cardia cancer ( GCC ) but not gastric noncardia cancer ( GNCC ) in a nested study from the Nutrition Intervention Trial in Linxian , China . OBJECTIVE We examined the relation between baseline serum selenium and the subsequent risk of death from ESCC , GCC , GNCC , heart disease ( HD ) , stroke , and total death over 15 y of follow-up ( 1986 - 2001 ) . DESIGN We measured baseline serum selenium concentrations  in 1103 subjects r and omly selected from a larger trial cohort . We identified 516 deaths during the 15-y follow up , including 75 from ESCC , 36 from GCC , 116 from HD , and 167 from stroke . Relative risks ( RRs ) and 95 % CIs were estimated by using Cox proportional hazards regression models . Reported RRs estimated the change in risk conferred by a 25 % increase in serum selenium relative to the population distribution . All estimates were adjusted for sex , age , smoking , drinking , and serum cholesterol . RESULTS We found significant inverse associations between baseline serum selenium and death from ESCC ( RR : 0.83 ; 95 % CI : 0.71 , 0.98 ) and GCC ( 0.75 ; 0.59 , 0.95 ) . Trends toward inverse associations were noted for death from HD ( 0.89 ; 0.78 , 1.01 ; P = 0.07 ) , but no association was noted for total death ( 0.96 ; 0.90 , 1.02 ) or stroke ( 0.99 ; 0.88 , 1.11 ) . CONCLUSION Population -wide selenium supplementation in the region of China with low serum selenium and high incidences of ESCC and GCC merits serious consideration BACKGROUND Selenium is an essential micronutrient with a recommended dietary allowance for adults of 55 mug/d . It functions as an essential constituent of selenoproteins . Although there is no evidence of selenium deficiency in the United States , people in many other areas of the world are selenium deficient , with the consequence that they are unable to express their selenoproteins fully . OBJECTIVE We carried out a supplementation trial in a selenium-deficient population in China to assess the requirement for selenium as selenite and as selenomethionine . DESIGN One hundred twenty subjects with an average selenium intake of 10 mug/d were r and omly assigned and administered tablets containing no selenium or amounts as high as 66 mug Se/d for 20 wk . Plasma was sample d before supplementation and at 4-wk intervals during supplementation and was assayed for the 2 plasma selenoproteins , glutathione peroxidase and selenoprotein P. RESULTS Full expression of glutathione peroxidase was achieved with 37 mug Se/d as selenomethionine and with 66 mug/d as selenite . Full expression of selenoprotein P was not achieved at the highest doses of either form . CONCLUSIONS Full expression of selenoprotein P requires a greater selenium intake than does full expression of plasma glutathione peroxidase . This suggests that selenoprotein P is a better indicator of selenium nutritional status than is glutathione peroxidase and that the recommended dietary allowance of selenium , which was set with the use of glutathione peroxidase as the index of selenium status , should be revised . Selenium as selenomethionine had nearly twice the bioavailability of selenium as selenite BACKGROUND Current US dietary recommendations for selenium are based on maximization of plasma glutathione peroxidase ( GSHPx ) activity according to data from one study of Chinese men . OBJECTIVE The effect of various amounts of supplemental selenium on GSHPx activities in blood of New Zeal and adults was investigated to calculate a selenium requirement for New Zeal and ers . The effect on plasma selenoprotein P and thyroid hormones was also investigated . DESIGN Fifty-two adults with low blood selenium concentrations ingested a placebo or 10 , 20 , 30 , or 40 microgram Se as L-selenomethionine daily for 20 wk . RESULTS Plasma and whole-blood GSHPx activities increased in all supplemented groups but reached a plateau only in the group receiving 40 microgram Se , as determined by statistical analysis . Increases in selenoprotein P were greater than those for selenium and GSHPx at all supplement intakes . Thyroxine concentrations decreased in supplemented groups but the decrease was significantly different from that in the control group only for the 10-microgram group and for all supplemented groups combined . CONCLUSIONS An upper estimated requirement of 90 microgram Se/d was calculated as the intake necessary for maximization of plasma GSHPx activity , as used in the derivation of the US recommended daily allowance . Our lower estimated requirement of 39 microgram Se/d was the intake necessary to reach two-thirds of maximal GSHPx activity , as was used in calculating the World Health Organization normative requirement . The lower estimate is a realistic goal for New Zeal and but the upper estimate could be achieved only with regular inclusion of high-selenium foods Sixty-one patients admitted with acute myocardial infa rct ion , and a symptom 's duration of less than 6 hr were r and omized into two groups . Immediately after hospitalisation , members of the verum group ( n = 32 ) received 500 mcg of selenium ( as sodium selenite ) . Thereafter they received a daily dosage of 100 mg coenzyme Q10 ( Bio-Quinone ) and 100 mcg selenium ( Bio-Selenium in the form of 1-seleno-methionine ) for a period of one year . The control group ( n = 29 ) were given matching 
    Output:
    
The limited trial evidence that is available to date does not support the use of selenium supplements in the primary prevention of CVD