human
***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: The objective was to determine the effect of daily supplementation with 30 mg of iron ( Fe ) plus 30 mg of zinc ( Zn ) for 3 months on Fe status of women of childbearing age . This was a r and omized double-blind , placebo-controlled trial . Eighty-one women ( 18–45 years ) were r and omly assigned to receive either a daily single dose of 30 mg of Fe ( group 1 ; n = 28 ) and 30 mg of Fe plus 30 mg of Zn ( group 2 ; n = 26 ) or placebo ( n = 27 ) for 3 months . Hemoglobin ( Hb ) , mean corpuscular volume , serum Fe , total iron-binding capacity , transferrin saturation , erythrocyte Zn protoporphyrin , serum ferritin ( SF ) , serum transferrin receptor ( TfR ) , total body Fe , serum Zn , and high-sensitivity C-reactive protein were measured at baseline and at the end of the study . At baseline , 3.7 , 28.4 , and 3.7 % of women had iron-deficiency anemia ( IDA ) , Fe deficiency without anemia , and depleted Fe stores , respectively . No significant differences on Fe status were found between groups before supplementation . After supplementation , group 2 showed a significant increase of Hb and total body Fe and a significant decrease of TfR compared with placebo ( p < 0.05 ) . Moreover , serum Zn increased significantly in group 2 compared with group 1 ( p < 0.01 ) and placebo ( p < 0.01 ) . In conclusion , daily supplementation with 30 mg of Fe plus 30 mg of Zn for 3 months improved significantly the Fe and Zn status of women , compared with those who received placebo . The positive effect of Fe supplementation on Fe status is enhanced by combined Zn supplementation In a study published elsewhere ( Wood and Elwood , 1966 ) the associations between the severity of various symptoms and haemoglobin levels in subjects who took part in a community survey is described . The present paper describes a double-blind r and omized clinical trial of the effects on these symptoms of  oral iron therapy  in a sample of the women seen during the community survey . In addition some limited data relating to a separate trial conducted in severely anaemic women identified in a hospital out-patient clinic are presented Our objective was to investigate the effects of iron depletion on adaptation to aerobic exercise , assessed by time to complete a 15-km cycle ergometer test . Forty-two iron-depleted ( serum ferritin < 16 microg/l ) , nonanemic ( Hb > 12 g/dl ) women ( 18 - 33 yr old ) received 100 mg of ferrous sulfate ( S ) or placebo ( P ) per day for 6 wk in a r and omized , double-blind trial . Subjects trained for 30 min/day , 5 days/wk at 75 - 85 % of maximum heart rate for the final 4 wk of the study . There were no group differences in baseline iron status or in 15-km time . Iron supplementation increased serum ferritin and decreased transferrin receptors in the S compared with the P group . The S and P groups decreased 15-km time and respiratory exchange ratio and increased work rate during the 15-km time trial after training . The decrease in 15-km time was greater in the S than in the P group ( P = 0.04 ) and could be partially attributed to increases in serum ferritin and Hb . These results indicate that iron deficiency without anemia impairs favorable adaptation to aerobic exercise We examined changes in iron status in 25 female varsity collegiate swimmers over the course of a competitive season via weekly capillary blood sampling . We also studied the effectiveness of moderate iron supplementation ( 39 mg/day ) in preventing expected changes in iron status via a double-blinded crossover design . On entry into the study , 17 of the swimmers had depleted iron stores ( plasma ferritin < 12 micrograms/L ) and 5 were anemic ( Hb < 120 g/L ) . After 5 wk of placebo treatment , hemoglobin decreased ( > or = 6 g/L ) in 44 % and increased in 12 % of the subjects . After 5 wk of iron supplementation , hemoglobin decreased in 16 % and increased in 24 % of the subjects . Likewise , after placebo treatment , plasma ferritin decreased ( > or = 5 micrograms/L ) in 24 % and increased in 4 % of the subjects , whereas iron supplementation result ed in decreases in 4 % and increases in 68 % of the subjects . In the absence of iron supplementation , hemoglobin levels decreased despite mean dietary iron intakes of 16.3 mg/day . These results show that moderate iron supplementation is effective in preventing decline in the iron status of female collegiate swimmers during a competitive season , but a higher dose of iron may be necessary to reverse their iron-deficient state IMPORTANCE Although blood donation is allowed every 8 weeks in the United States , recovery of hemoglobin to the currently accepted st and ard ( 12.5 g/dL ) is frequently delayed , and some donors become anemic . OBJECTIVE To determine the effect of oral iron supplementation on hemoglobin recovery time ( days to recovery of 80 % of hemoglobin removed ) and recovery of iron stores in iron-depleted ( " low ferritin , " ≤26 ng/mL ) and iron-replete ( " higher ferritin , " > 26 ng/mL ) blood donors . DESIGN , SETTING , AND PARTICIPANTS R and omized , nonblinded clinical trial of blood donors stratified by ferritin level , sex , and age conducted in 4 regional blood centers in the United States in 2012 . Included were 215 eligible participants aged 18 to 79 years who had not donated whole blood or red blood cells within 4 months . INTERVENTIONS One tablet of ferrous gluconate ( 37.5 mg of elemental iron ) daily or no iron for 24 weeks ( 168 days ) after donating a unit of whole blood ( 500 mL ) . MAIN OUTCOMES AND MEASURES Time to recovery of 80 % of the postdonation decrease in hemoglobin and recovery of ferritin level to baseline as a measure of iron stores . RESULTS The mean baseline hemoglobin levels were comparable in the iron and no-iron groups and declined from a mean ( SD ) of 13.4 ( 1.1 ) g/dL to 12.0 ( 1.2 ) g/dL after donation in the low-ferritin group and from 14.2 ( 1.1 ) g/dL to 12.9 ( 1.2 ) g/dL in the higher-ferritin group . Compared with participants who did not receive iron supplementation , those who received iron supplementation had shortened time to 80 % hemoglobin recovery in both the low-ferritin ( mean , 32 days , interquartile range [ IQR ] , 30 - 34 , vs 158 days , IQR , 126->168 ) and higher-ferritin groups ( 31 days , IQR , 29 - 33 , vs 78 days , IQR , 66 - 95 ) . Median time to recovery to baseline ferritin levels in the low-ferritin group taking iron was 21 days ( IQR , 12 - 84 ) . For participants not taking iron , recovery to baseline was longer than 168 days ( IQR , 128->168 ) . Median time to recovery to baseline in the higher-ferritin group taking iron was 107 days ( IQR , 75 - 141 ) , and for participants not taking iron , recovery to baseline was longer than 168 days ( IQR , > 168->168 ) . Recovery of iron stores in all participants who received supplements took a median of 76 days ( IQR , 20 - 126 ) ; for participants not taking iron , median recovery time was longer than 168 days ( IQR , 147->168 days ; P < .001 ) . Without iron supplements , 67 % of participants did not recover iron stores by 168 days . CONCLUSIONS AND RELEVANCE Among blood donors with normal hemoglobin levels  , low-dose iron supplementation , compared with no supplementation , reduced time to 80 % recovery of the postdonation decrease in hemoglobin concentration in donors with low ferritin ( ≤26 ng/mL ) or higher ferritin ( > 26 ng/mL ) . TRIAL REGISTRATION clinical trials.gov Identifier : NCT01555060 BACKGROUND Iron deficiency without anemia has been shown to reduce both muscle-tissue oxidative capacity and endurance in animals . However , the consequences of iron deficiency in humans remain unclear . OBJECTIVE We investigated the effects of iron supplementation on adaptation to aerobic training among marginally iron-depleted women . We hypothesized that iron supplementation for 6 wk would significantly improve iron status and maximal oxygen uptake ( VO(2)max ) after 4 wk of concurrent aerobic training . DESIGN Forty-one untrained , iron-depleted , nonanemic women were r and omly assigned to receive either 50 mg FeSO(4 ) or a placebo twice daily for 6 wk in a double-blind trial . All subjects trained on cycle ergometers 5 d/wk for 4 wk , beginning on week 3 of the study . RESULTS Six weeks of iron supplementation significantly improved serum ferritin and serum transferrin receptor ( sTfR ) concentrations and transferrin saturation without affecting hemoglobin concentrations or hematocrit . Average VO(2)max and maximal respiratory exchange ratio improved in both the placebo and iron groups after training ; however , the iron group experienced significantly greater improvements in VO(2)max . Both iron-status and fitness outcomes were analyzed after stratifying by baseline sTfR concentration ( > and < or = 8.0 mg/L ) , which showed that the previously observed treatment effects were due to iron-status and fitness improvements among subjects with poor baseline iron status . CONCLUSIONS Our findings strongly suggest that iron deficiency without anemia but with elevated sTfR status impairs aerobic adaptation among previously untrained women and that this can be corrected with iron supplementation Studies on the treatment and prevention of iron deficiency anemia , in pregnant and nonpregnant women and in men , were conducted in Thail and and Burma . The effects of the dose of Fe , duration of Fe administration , additional supplementation with folate , mode of supplement delivery ( either supervised or unsupervised ) , and the presence of Hb(AE ) were studied . The frequency and severity of side effects were also recorded . Fe administration result ed in an increase in hemoglobin concentration in all anemic individuals but approximately 20 % failed to reach normality . The length of administration and the dose influenced the results . Frequency and severity of side effects increased with the dose of Fe administered . Folate supplementation did not affect the results . It appears possible to integrate a program of prevention and treatment of Fe deficiency anemia in a primary health-care system but the constraints and limitations of achievable results should be recognized Response of iron , copper , and zinc status to supplementation with Zn or a combination of Zn and Fe was assessed in adult females in a 10-wk study . Group Z received 50 mg Zn/d as Zn gluconate ; group F-Z received 50 mg Fe as ferrous sulfate monohydrate in addition to the Zn . For Group Z , serum ferritin , hematocrit , and erythrocyte Cu , Zn-superoxide dismutase ( ESOD ) were significantly lower ( p less than 0.05 ) after 10 wk supplementation compared with pretreatment levels . Serum Zn increased ( p less than 0.01 ) but no change occurred in serum ceruloplasmin , hemoglobin , or salivary sediment Zn with treatment . For Group F-Z ESOD decreased with treatment as did salivary sediment Zn ( p less than 0.05 ) . Serum ferritin and serum Zn increased significantly , but hemoglobin , hematocrit , and ceruloplasmin were not affected by this treatment . Supplementation with Zn poses a risk to Fe and Cu status . Inclusion of Fe with Zn ameliorates the effect on Fe but not on Cu status BACKGROUND We previously showed that iron supplementation significantly improves iron status and maximal work capacity in previously untrained , marginally iron-deficient women with a baseline serum transferrin receptor concentration > 8.0 mg/L. However , the effect of transferrin receptor status on adaptation in endurance capacity after aerobic training in these subjects has not been fully explored . OBJECTIVE Our objective was to examine the effect of baseline serum transferrin receptor status on adaptations in endurance capacity . DESIGN Forty-one untrained , iron-depleted , nonanemic women were r and omly assigned to receive either 100 mg FeSO(4 ) or a placebo for 6 wk in a double-blind trial . All subjects trained on cycle ergometers 5 d/wk for the last 4 wk of the study . Endurance capacity was assessed at baseline and after treatment by using a 15-km time trial conducted on a cycle ergometer . RESULTS Significant treatment effects were observed for time to complete the 15-km time trial , work rate , and percentage of maximal oxygen uptake in subjects with a baseline serum transferrin receptor concentration > 8.0 mg/L. No significant treatment effects were observed in subjects with a normal 
    Output:
    
agent
***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: The objective was to determine the effect of daily supplementation with 30 mg of iron ( Fe ) plus 30 mg of zinc ( Zn ) for 3 months on Fe status of women of childbearing age . This was a r and omized double-blind , placebo-controlled trial . Eighty-one women ( 18–45 years ) were r and omly assigned to receive either a daily single dose of 30 mg of Fe ( group 1 ; n = 28 ) and 30 mg of Fe plus 30 mg of Zn ( group 2 ; n = 26 ) or placebo ( n = 27 ) for 3 months . Hemoglobin ( Hb ) , mean corpuscular volume , serum Fe , total iron-binding capacity , transferrin saturation , erythrocyte Zn protoporphyrin , serum ferritin ( SF ) , serum transferrin receptor ( TfR ) , total body Fe , serum Zn , and high-sensitivity C-reactive protein were measured at baseline and at the end of the study . At baseline , 3.7 , 28.4 , and 3.7 % of women had iron-deficiency anemia ( IDA ) , Fe deficiency without anemia , and depleted Fe stores , respectively . No significant differences on Fe status were found between groups before supplementation . After supplementation , group 2 showed a significant increase of Hb and total body Fe and a significant decrease of TfR compared with placebo ( p < 0.05 ) . Moreover , serum Zn increased significantly in group 2 compared with group 1 ( p < 0.01 ) and placebo ( p < 0.01 ) . In conclusion , daily supplementation with 30 mg of Fe plus 30 mg of Zn for 3 months improved significantly the Fe and Zn status of women , compared with those who received placebo . The positive effect of Fe supplementation on Fe status is enhanced by combined Zn supplementation In a study published elsewhere ( Wood and Elwood , 1966 ) the associations between the severity of various symptoms and haemoglobin levels in subjects who took part in a community survey is described . The present paper describes a double-blind r and omized clinical trial of the effects on these symptoms of  oral iron therapy  in a sample of the women seen during the community survey . In addition some limited data relating to a separate trial conducted in severely anaemic women identified in a hospital out-patient clinic are presented Our objective was to investigate the effects of iron depletion on adaptation to aerobic exercise , assessed by time to complete a 15-km cycle ergometer test . Forty-two iron-depleted ( serum ferritin < 16 microg/l ) , nonanemic ( Hb > 12 g/dl ) women ( 18 - 33 yr old ) received 100 mg of ferrous sulfate ( S ) or placebo ( P ) per day for 6 wk in a r and omized , double-blind trial . Subjects trained for 30 min/day , 5 days/wk at 75 - 85 % of maximum heart rate for the final 4 wk of the study . There were no group differences in baseline iron status or in 15-km time . Iron supplementation increased serum ferritin and decreased transferrin receptors in the S compared with the P group . The S and P groups decreased 15-km time and respiratory exchange ratio and increased work rate during the 15-km time trial after training . The decrease in 15-km time was greater in the S than in the P group ( P = 0.04 ) and could be partially attributed to increases in serum ferritin and Hb . These results indicate that iron deficiency without anemia impairs favorable adaptation to aerobic exercise We examined changes in iron status in 25 female varsity collegiate swimmers over the course of a competitive season via weekly capillary blood sampling . We also studied the effectiveness of moderate iron supplementation ( 39 mg/day ) in preventing expected changes in iron status via a double-blinded crossover design . On entry into the study , 17 of the swimmers had depleted iron stores ( plasma ferritin < 12 micrograms/L ) and 5 were anemic ( Hb < 120 g/L ) . After 5 wk of placebo treatment , hemoglobin decreased ( > or = 6 g/L ) in 44 % and increased in 12 % of the subjects . After 5 wk of iron supplementation , hemoglobin decreased in 16 % and increased in 24 % of the subjects . Likewise , after placebo treatment , plasma ferritin decreased ( > or = 5 micrograms/L ) in 24 % and increased in 4 % of the subjects , whereas iron supplementation result ed in decreases in 4 % and increases in 68 % of the subjects . In the absence of iron supplementation , hemoglobin levels decreased despite mean dietary iron intakes of 16.3 mg/day . These results show that moderate iron supplementation is effective in preventing decline in the iron status of female collegiate swimmers during a competitive season , but a higher dose of iron may be necessary to reverse their iron-deficient state IMPORTANCE Although blood donation is allowed every 8 weeks in the United States , recovery of hemoglobin to the currently accepted st and ard ( 12.5 g/dL ) is frequently delayed , and some donors become anemic . OBJECTIVE To determine the effect of oral iron supplementation on hemoglobin recovery time ( days to recovery of 80 % of hemoglobin removed ) and recovery of iron stores in iron-depleted ( " low ferritin , " ≤26 ng/mL ) and iron-replete ( " higher ferritin , " > 26 ng/mL ) blood donors . DESIGN , SETTING , AND PARTICIPANTS R and omized , nonblinded clinical trial of blood donors stratified by ferritin level , sex , and age conducted in 4 regional blood centers in the United States in 2012 . Included were 215 eligible participants aged 18 to 79 years who had not donated whole blood or red blood cells within 4 months . INTERVENTIONS One tablet of ferrous gluconate ( 37.5 mg of elemental iron ) daily or no iron for 24 weeks ( 168 days ) after donating a unit of whole blood ( 500 mL ) . MAIN OUTCOMES AND MEASURES Time to recovery of 80 % of the postdonation decrease in hemoglobin and recovery of ferritin level to baseline as a measure of iron stores . RESULTS The mean baseline hemoglobin levels were comparable in the iron and no-iron groups and declined from a mean ( SD ) of 13.4 ( 1.1 ) g/dL to 12.0 ( 1.2 ) g/dL after donation in the low-ferritin group and from 14.2 ( 1.1 ) g/dL to 12.9 ( 1.2 ) g/dL in the higher-ferritin group . Compared with participants who did not receive iron supplementation , those who received iron supplementation had shortened time to 80 % hemoglobin recovery in both the low-ferritin ( mean , 32 days , interquartile range [ IQR ] , 30 - 34 , vs 158 days , IQR , 126->168 ) and higher-ferritin groups ( 31 days , IQR , 29 - 33 , vs 78 days , IQR , 66 - 95 ) . Median time to recovery to baseline ferritin levels in the low-ferritin group taking iron was 21 days ( IQR , 12 - 84 ) . For participants not taking iron , recovery to baseline was longer than 168 days ( IQR , 128->168 ) . Median time to recovery to baseline in the higher-ferritin group taking iron was 107 days ( IQR , 75 - 141 ) , and for participants not taking iron , recovery to baseline was longer than 168 days ( IQR , > 168->168 ) . Recovery of iron stores in all participants who received supplements took a median of 76 days ( IQR , 20 - 126 ) ; for participants not taking iron , median recovery time was longer than 168 days ( IQR , 147->168 days ; P < .001 ) . Without iron supplements , 67 % of participants did not recover iron stores by 168 days . CONCLUSIONS AND RELEVANCE Among blood donors with normal hemoglobin levels  , low-dose iron supplementation , compared with no supplementation , reduced time to 80 % recovery of the postdonation decrease in hemoglobin concentration in donors with low ferritin ( ≤26 ng/mL ) or higher ferritin ( > 26 ng/mL ) . TRIAL REGISTRATION clinical trials.gov Identifier : NCT01555060 BACKGROUND Iron deficiency without anemia has been shown to reduce both muscle-tissue oxidative capacity and endurance in animals . However , the consequences of iron deficiency in humans remain unclear . OBJECTIVE We investigated the effects of iron supplementation on adaptation to aerobic training among marginally iron-depleted women . We hypothesized that iron supplementation for 6 wk would significantly improve iron status and maximal oxygen uptake ( VO(2)max ) after 4 wk of concurrent aerobic training . DESIGN Forty-one untrained , iron-depleted , nonanemic women were r and omly assigned to receive either 50 mg FeSO(4 ) or a placebo twice daily for 6 wk in a double-blind trial . All subjects trained on cycle ergometers 5 d/wk for 4 wk , beginning on week 3 of the study . RESULTS Six weeks of iron supplementation significantly improved serum ferritin and serum transferrin receptor ( sTfR ) concentrations and transferrin saturation without affecting hemoglobin concentrations or hematocrit . Average VO(2)max and maximal respiratory exchange ratio improved in both the placebo and iron groups after training ; however , the iron group experienced significantly greater improvements in VO(2)max . Both iron-status and fitness outcomes were analyzed after stratifying by baseline sTfR concentration ( > and < or = 8.0 mg/L ) , which showed that the previously observed treatment effects were due to iron-status and fitness improvements among subjects with poor baseline iron status . CONCLUSIONS Our findings strongly suggest that iron deficiency without anemia but with elevated sTfR status impairs aerobic adaptation among previously untrained women and that this can be corrected with iron supplementation Studies on the treatment and prevention of iron deficiency anemia , in pregnant and nonpregnant women and in men , were conducted in Thail and and Burma . The effects of the dose of Fe , duration of Fe administration , additional supplementation with folate , mode of supplement delivery ( either supervised or unsupervised ) , and the presence of Hb(AE ) were studied . The frequency and severity of side effects were also recorded . Fe administration result ed in an increase in hemoglobin concentration in all anemic individuals but approximately 20 % failed to reach normality . The length of administration and the dose influenced the results . Frequency and severity of side effects increased with the dose of Fe administered . Folate supplementation did not affect the results . It appears possible to integrate a program of prevention and treatment of Fe deficiency anemia in a primary health-care system but the constraints and limitations of achievable results should be recognized Response of iron , copper , and zinc status to supplementation with Zn or a combination of Zn and Fe was assessed in adult females in a 10-wk study . Group Z received 50 mg Zn/d as Zn gluconate ; group F-Z received 50 mg Fe as ferrous sulfate monohydrate in addition to the Zn . For Group Z , serum ferritin , hematocrit , and erythrocyte Cu , Zn-superoxide dismutase ( ESOD ) were significantly lower ( p less than 0.05 ) after 10 wk supplementation compared with pretreatment levels . Serum Zn increased ( p less than 0.01 ) but no change occurred in serum ceruloplasmin , hemoglobin , or salivary sediment Zn with treatment . For Group F-Z ESOD decreased with treatment as did salivary sediment Zn ( p less than 0.05 ) . Serum ferritin and serum Zn increased significantly , but hemoglobin , hematocrit , and ceruloplasmin were not affected by this treatment . Supplementation with Zn poses a risk to Fe and Cu status . Inclusion of Fe with Zn ameliorates the effect on Fe but not on Cu status BACKGROUND We previously showed that iron supplementation significantly improves iron status and maximal work capacity in previously untrained , marginally iron-deficient women with a baseline serum transferrin receptor concentration > 8.0 mg/L. However , the effect of transferrin receptor status on adaptation in endurance capacity after aerobic training in these subjects has not been fully explored . OBJECTIVE Our objective was to examine the effect of baseline serum transferrin receptor status on adaptations in endurance capacity . DESIGN Forty-one untrained , iron-depleted , nonanemic women were r and omly assigned to receive either 100 mg FeSO(4 ) or a placebo for 6 wk in a double-blind trial . All subjects trained on cycle ergometers 5 d/wk for the last 4 wk of the study . Endurance capacity was assessed at baseline and after treatment by using a 15-km time trial conducted on a cycle ergometer . RESULTS Significant treatment effects were observed for time to complete the 15-km time trial , work rate , and percentage of maximal oxygen uptake in subjects with a baseline serum transferrin receptor concentration > 8.0 mg/L. No significant treatment effects were observed in subjects with a normal 
    Output:
    