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: BACKGROUND Adjustments in zinc absorption and endogenous excretion maintain zinc homeostasis in nonpregnant adults fed low-zinc diets . The effects on zinc homeostasis of a low zinc intake during pregnancy and lactation have not been described in a longitudinal study . OBJECTIVE We examined longitudinal changes in fractional zinc absorption ( FZA ) and zinc kinetics in 10 healthy Brazilian women who habitually consumed a marginal zinc diet ( approximately 9 mg Zn/d ) . DESIGN  Zinc status was measured at 10 - 12 ( early pregnancy ; EP ) and 34 - 36 ( late pregnancy ; LP ) wk of pregnancy and at 7 - 8 wk after delivery ( early lactation ; EL ) . Zinc kinetics and FZA were studied by using stable isotopic tracers . RESULTS Zinc intake averaged 9 + /- 3 mg/d throughout the study . FZA increased from 29 + /- 6 % at EP to 43 + /- 10 % at LP and to 39 + /- 13 % at EL ( P < 0.05 ) . FZA was inversely related to plasma zinc at EL ( r = -0.73 , P = 0.02 ) and LP ( r = -0.72 , P = 0.07 ) . Plasma zinc mass was 23 % greater at LP than at EP or EL ( P < 0.05 ) . The amount of zinc ( mg/d ) that fluxed between plasma and the most-rapidly-turning-over extravascular pool was 53 % greater at LP than at EP or EL ( P < 0.05 ) . The zinc flux between plasma and the less-rapidly-turning-over zinc pool at EL was 27 % greater than that at EP or LP , but this difference was not significant . CONCLUSIONS FZA increased significantly in women with marginal zinc intakes during pregnancy and lactation ; the increase was higher in women with low plasma zinc . Plasma zinc was distributed into a different exchangeable pool at LP than at EL Prenatal iron supplements may adversely influence zinc absorption during pregnancy . To examine the impact of prenatal iron supplements on supplemental zinc absorption , fractional zinc absorption was measured in 47 pregnant Peruvian women during the third trimester of pregnancy ( 33 + /- 1 wk gestation ) . Of these 47 women , 30 received daily prenatal supplements  from wk 10 - 24 of pregnancy until delivery . Supplements contained 60 mg of Fe and 250 microg of folate without [ iron group ( Fe ) , n = 16 ] or with [ iron and zinc supplemented group ( Fe + Zn ) , n = 14 ] 15 mg of Zn . The remaining 17 women [ unsupplemented control group ( C ) ] received no prenatal supplementation .  Zinc concentrations were measured in plasma , urine and cord blood and percentage zinc absorption was determined following dosing with oral ( (67)Zn ) and intravenous ( (70)Zn ) stable zinc isotopes . Percentage zinc absorption was significantly lower than controls in fasting women receiving iron- containing prenatal supplements ( 20.5 + /- 6.4 vs. 20.2 + /- 4.6 vs. 47.0 + /- 12.6 % , Fe , Fe + Zn and C groups , respectively , P : < 0.0001 , n = 40 ) . Plasma zinc concentrations were also significantly lower in the Fe group compared to the C group ( 8.2 + /- 2.2 vs. 9.2 + /- 2.2 vs. 10.9 + /- 1 . 8 micromol/L , Fe , Fe + Zn and C groups , respectively , P : = 0.002 ) , and cord zinc concentrations were significantly related to maternal plasma Zn levels ( y = 6.383 + 0.555x , r = 0.486 , P : = 0.002 ) . The inclusion of zinc in prenatal supplements may reduce the potential for iron supplements to adversely influence zinc status in population s at risk for deficiency of both these nutrients Postpartum lactating ( n = 12 ) and nonlactating ( n = 11 ) women and never pregnant women ( n = 14 ) collected urine sample s and diet records 2 d each month for 6 mo to determine whether postpartum women conserved urinary calcium , magnesium , or zinc . Mean daily excretions were analyzed by repeated- measures analysis of variance and covariance to assess group and time effects . Lactating women excreted less urinary calcium ( 1 - 6 mo ) than never pregnant ( n = 8) and nonlactating ( n = 4 ) women who did not use oral contraceptives ( P < 0.01 ) ; however , excretion rose ( P < 0.05 ) by 3 mo postpartum . In the nonlactating and never pregnant groups , women using oral contraceptives excreted less urinary calcium than the other women ( P < 0.01 ) . Lactating women excreted less urinary zinc ( 1 - 6 mo ) than did control and non-lactating women ( P < 0.01 ) . Mechanisms may possibly be operating during lactation that depress urinary calcium for > or = 2 mo and urinary zinc < or = 6 mo postpartum To estimate the effect of maternal zinc deficiency on pregnancy outcomes , we conducted a zinc supplementation trial in an urban shantytown in Lima , Peru , a population with habitual low zinc intakes . Beginning at 10 - 24 wk gestation , 1295 mothers were r and omly assigned to receive prenatal supplements containing 60 mg iron and 250 ( g folate , with or without 15 mg zinc . Women were followed up monthly during pregnancy . At birth , newborn weight was recorded , and crownheel length , head circumference and other circumferences and skinfold thicknesses were assessed on d 1 . At delivery , 1016 remained in the study ;  duration of pregnancy  was known for all women , and birth weight information was available for 957 newborns . No differences were noted in duration of pregnancy ( 39.4 + /- 2.2 vs. 39 . 5 + /- 2.0 wk ) or birth weight ( 3267 + /- 461 vs. 3300 + /- 498 g ) by prenatal supplement type ( iron + folate + zinc vs. iron + folate ; P > 0.05 ) , and there were no differences in the rates of preterm ( < 37 wk ) or post-term ( > 42 wk ) delivery , low birth weight ( < 2500 g ) or high birth weight ( > 4000 g ) . Finally , there were no differences by prenatal supplement type in newborn head circumference , crownheel length , chest circumference , mid-upper arm circumference , calf circumference or skinfold thickness at any of three sites . Adjustment for covariates and confounding factors did not alter these results . Adding zinc to prenatal iron and folate tablets did not affect duration of pregnancy or size at birth in this population BACKGROUND Maternal zinc deficiency during pregnancy may be widespread among women in developing countries , but few data are available on whether prenatal zinc supplementation improves maternal and neonatal zinc status . OBJECTIVE We studied whether maternal zinc supplementation improved the zinc status of mothers and neonates participating in a supplementation trial in a shantytown in Lima , Peru . DESIGN Beginning at gestation week 10 - 24 , 1295 mothers were r and omly assigned to receive prenatal supplements containing 60 mg Fe and 250 microg folate , with or without 15 mg Zn .  Venous blood and urine sample s were collected at enrollment , at gestation week 28 - 30 , and at gestation week 37 - 38 . At birth , a sample of cord vein blood was collected . We measured serum zinc concentrations in 538 women , urinary zinc concentrations in 521 women , and cord zinc concentrations in 252 neonates . RESULTS At 28 - 30 and 37 - 38 wk , mothers receiving zinc supplements had higher serum zinc concentrations than mothers who did not receive zinc ( 8.8 + /- 1.9 compared with 8.4 + /- 1.5 micromol/L and 8.6 + /- 1.5 compared with 8.3 + /- 1.4 micromol/L , respectively ) . Urinary zinc concentrations were also higher in mothers who received supplemental zinc ( P < 0.05 ) . After adjustment for covariates and confounding factors , neonates of mothers receiving zinc supplements had higher cord zinc concentrations than neonates of mothers who did not receive zinc ( 12.7 + /- 2.3 compared with 12.1 + /- 2.1 micromol/L ) . Despite supplementation , maternal and neonatal zinc concentrations remained lower than values reported for well-nourished population s. CONCLUSION Adding zinc to prenatal iron and folate tablets improved maternal and neonatal zinc status , but higher doses of zinc are likely needed to further improve maternal and neonatal zinc status in this population BACKGROUND Little is known about how maternal zinc intake influences growth in utero and in postnatal life in humans . OBJECTIVE We aim ed to assess the effect of maternal zinc supplementation during pregnancy on infant growth through age 1 y. DESIGN A double-blind , r and omized controlled trial of prenatal zinc supplementation was conducted from 1995 to 1997 in Lima , Peru . Women ( n = 1295 ) were enrolled at 15.6 + /- 4.6 wk gestation and assigned to receive daily supplements with zinc ( 15 mg Zn + 60 mg Fe + 250 microg folic acid ) or without zinc ( 60 Fe + 250 microg folic acid ) through pregnancy to 1 mo after delivery . At birth , 546 infants were followed for 12 mo to assess growth . Anthropometric measures of body size and composition were collected monthly , and morbidity and dietary intake surveillance was carried out weekly . RESULTS No differences in maternal socioeconomic characteristics by treatment group or follow-up period were found . Infants born to mothers prenatally supplemented with zinc had significantly ( P < 0.05 ) larger average growth measures beginning in month 4 and continuing through month 12 . In longitudinal regression modeling , prenatal zinc was associated with greater weight ( by 0.58 + /- 0.12 kg ; P < 0.001 ) , calf circumference ( by 1.01 + /- 0.21 cm ; P < 0.001 ) , chest circumference ( by 0.60 + /- 0.20 cm ; P = 0.002 ) , and calf muscle area ( by 35.78 + /- 14.75 mm(2 ) ; P = 0.01 ) after adjustment for a range of covariates . No effect was observed for linear growth . CONCLUSION Maternal zinc supplementation in this population was associated with offspring growth , which is suggestive of lean tissue mass accretion BACKGROUND There is a major increase in endogenous zinc excretion , specifically via the mammary gl and , in early human lactation . Whereas fractional absorption of dietary zinc has been reported to increase in early human lactation , it is not known to what extent adaptive mechanisms may maintain zinc homeostasis , especially when dietary zinc intake is relatively low . OBJECTIVE The objective of this study was to quantitate major variables of zinc homeostasis during early lactation in subjects from a population whose habitual dietary zinc intake is low . DESIGN We studied 18 free-living lactating women from a rural community of northeast China whose infants were exclusively breast-fed .  The subjects were studied at approximately 2 mo of lactation with use of stable isotopes of zinc and metabolic collection techniques .  Milk volume was measured with use of a deuterium enrichment method . RESULTS The mean ( + /-SD ) secretion of zinc in milk was 2.01 + /- 0.97 mg/d , the intake of zinc was 7.64 + /- 1.61 mg/d , and the fractional absorption of zinc was 0.53 + /- 0.09 , for a total daily zinc absorption of 4.00 + /- 0.71 mg/d . Endogenous zinc excretion in urine and feces was 0.30 + /- 0.10 and 1.66 + /- 0.97 mg/d , respectively . CONCLUSIONS Zinc balance , including zinc secreted in breast milk , was maintained at approximately 2 mo of lactation in women whose habitual diet was low in zinc . Homeostasis was achieved by high fractional absorption of zinc and intestinal conservation of endogenous fecal zinc Dietary zinc ( Zn ) intake and selected biochemical indices of Zn status were studied longitudinally at monthly intervals in 46 pregnant middle-income women , 10 of whom received a daily supplement of 15 mg Zn .  Mean dietary Zn intake for the nonsupplemented subjects ( group A ) was 11.3 + /- 4 
    Output:
    
agent
We hypothesize , therefore , that zinc homeostatic adjustments during pregnancy and lactation improve zinc utilization sufficiently to provide the increased zinc needs in these stages and , therefore , mitigate immediate detrimental effects due to a low zinc intake .
***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: BACKGROUND Adjustments in zinc absorption and endogenous excretion maintain zinc homeostasis in nonpregnant adults fed low-zinc diets . The effects on zinc homeostasis of a low zinc intake during pregnancy and lactation have not been described in a longitudinal study . OBJECTIVE We examined longitudinal changes in fractional zinc absorption ( FZA ) and zinc kinetics in 10 healthy Brazilian women who habitually consumed a marginal zinc diet ( approximately 9 mg Zn/d ) . DESIGN  Zinc status was measured at 10 - 12 ( early pregnancy ; EP ) and 34 - 36 ( late pregnancy ; LP ) wk of pregnancy and at 7 - 8 wk after delivery ( early lactation ; EL ) . Zinc kinetics and FZA were studied by using stable isotopic tracers . RESULTS Zinc intake averaged 9 + /- 3 mg/d throughout the study . FZA increased from 29 + /- 6 % at EP to 43 + /- 10 % at LP and to 39 + /- 13 % at EL ( P < 0.05 ) . FZA was inversely related to plasma zinc at EL ( r = -0.73 , P = 0.02 ) and LP ( r = -0.72 , P = 0.07 ) . Plasma zinc mass was 23 % greater at LP than at EP or EL ( P < 0.05 ) . The amount of zinc ( mg/d ) that fluxed between plasma and the most-rapidly-turning-over extravascular pool was 53 % greater at LP than at EP or EL ( P < 0.05 ) . The zinc flux between plasma and the less-rapidly-turning-over zinc pool at EL was 27 % greater than that at EP or LP , but this difference was not significant . CONCLUSIONS FZA increased significantly in women with marginal zinc intakes during pregnancy and lactation ; the increase was higher in women with low plasma zinc . Plasma zinc was distributed into a different exchangeable pool at LP than at EL Prenatal iron supplements may adversely influence zinc absorption during pregnancy . To examine the impact of prenatal iron supplements on supplemental zinc absorption , fractional zinc absorption was measured in 47 pregnant Peruvian women during the third trimester of pregnancy ( 33 + /- 1 wk gestation ) . Of these 47 women , 30 received daily prenatal supplements  from wk 10 - 24 of pregnancy until delivery . Supplements contained 60 mg of Fe and 250 microg of folate without [ iron group ( Fe ) , n = 16 ] or with [ iron and zinc supplemented group ( Fe + Zn ) , n = 14 ] 15 mg of Zn . The remaining 17 women [ unsupplemented control group ( C ) ] received no prenatal supplementation .  Zinc concentrations were measured in plasma , urine and cord blood and percentage zinc absorption was determined following dosing with oral ( (67)Zn ) and intravenous ( (70)Zn ) stable zinc isotopes . Percentage zinc absorption was significantly lower than controls in fasting women receiving iron- containing prenatal supplements ( 20.5 + /- 6.4 vs. 20.2 + /- 4.6 vs. 47.0 + /- 12.6 % , Fe , Fe + Zn and C groups , respectively , P : < 0.0001 , n = 40 ) . Plasma zinc concentrations were also significantly lower in the Fe group compared to the C group ( 8.2 + /- 2.2 vs. 9.2 + /- 2.2 vs. 10.9 + /- 1 . 8 micromol/L , Fe , Fe + Zn and C groups , respectively , P : = 0.002 ) , and cord zinc concentrations were significantly related to maternal plasma Zn levels ( y = 6.383 + 0.555x , r = 0.486 , P : = 0.002 ) . The inclusion of zinc in prenatal supplements may reduce the potential for iron supplements to adversely influence zinc status in population s at risk for deficiency of both these nutrients Postpartum lactating ( n = 12 ) and nonlactating ( n = 11 ) women and never pregnant women ( n = 14 ) collected urine sample s and diet records 2 d each month for 6 mo to determine whether postpartum women conserved urinary calcium , magnesium , or zinc . Mean daily excretions were analyzed by repeated- measures analysis of variance and covariance to assess group and time effects . Lactating women excreted less urinary calcium ( 1 - 6 mo ) than never pregnant ( n = 8) and nonlactating ( n = 4 ) women who did not use oral contraceptives ( P < 0.01 ) ; however , excretion rose ( P < 0.05 ) by 3 mo postpartum . In the nonlactating and never pregnant groups , women using oral contraceptives excreted less urinary calcium than the other women ( P < 0.01 ) . Lactating women excreted less urinary zinc ( 1 - 6 mo ) than did control and non-lactating women ( P < 0.01 ) . Mechanisms may possibly be operating during lactation that depress urinary calcium for > or = 2 mo and urinary zinc < or = 6 mo postpartum To estimate the effect of maternal zinc deficiency on pregnancy outcomes , we conducted a zinc supplementation trial in an urban shantytown in Lima , Peru , a population with habitual low zinc intakes . Beginning at 10 - 24 wk gestation , 1295 mothers were r and omly assigned to receive prenatal supplements containing 60 mg iron and 250 ( g folate , with or without 15 mg zinc . Women were followed up monthly during pregnancy . At birth , newborn weight was recorded , and crownheel length , head circumference and other circumferences and skinfold thicknesses were assessed on d 1 . At delivery , 1016 remained in the study ;  duration of pregnancy  was known for all women , and birth weight information was available for 957 newborns . No differences were noted in duration of pregnancy ( 39.4 + /- 2.2 vs. 39 . 5 + /- 2.0 wk ) or birth weight ( 3267 + /- 461 vs. 3300 + /- 498 g ) by prenatal supplement type ( iron + folate + zinc vs. iron + folate ; P > 0.05 ) , and there were no differences in the rates of preterm ( < 37 wk ) or post-term ( > 42 wk ) delivery , low birth weight ( < 2500 g ) or high birth weight ( > 4000 g ) . Finally , there were no differences by prenatal supplement type in newborn head circumference , crownheel length , chest circumference , mid-upper arm circumference , calf circumference or skinfold thickness at any of three sites . Adjustment for covariates and confounding factors did not alter these results . Adding zinc to prenatal iron and folate tablets did not affect duration of pregnancy or size at birth in this population BACKGROUND Maternal zinc deficiency during pregnancy may be widespread among women in developing countries , but few data are available on whether prenatal zinc supplementation improves maternal and neonatal zinc status . OBJECTIVE We studied whether maternal zinc supplementation improved the zinc status of mothers and neonates participating in a supplementation trial in a shantytown in Lima , Peru . DESIGN Beginning at gestation week 10 - 24 , 1295 mothers were r and omly assigned to receive prenatal supplements containing 60 mg Fe and 250 microg folate , with or without 15 mg Zn .  Venous blood and urine sample s were collected at enrollment , at gestation week 28 - 30 , and at gestation week 37 - 38 . At birth , a sample of cord vein blood was collected . We measured serum zinc concentrations in 538 women , urinary zinc concentrations in 521 women , and cord zinc concentrations in 252 neonates . RESULTS At 28 - 30 and 37 - 38 wk , mothers receiving zinc supplements had higher serum zinc concentrations than mothers who did not receive zinc ( 8.8 + /- 1.9 compared with 8.4 + /- 1.5 micromol/L and 8.6 + /- 1.5 compared with 8.3 + /- 1.4 micromol/L , respectively ) . Urinary zinc concentrations were also higher in mothers who received supplemental zinc ( P < 0.05 ) . After adjustment for covariates and confounding factors , neonates of mothers receiving zinc supplements had higher cord zinc concentrations than neonates of mothers who did not receive zinc ( 12.7 + /- 2.3 compared with 12.1 + /- 2.1 micromol/L ) . Despite supplementation , maternal and neonatal zinc concentrations remained lower than values reported for well-nourished population s. CONCLUSION Adding zinc to prenatal iron and folate tablets improved maternal and neonatal zinc status , but higher doses of zinc are likely needed to further improve maternal and neonatal zinc status in this population BACKGROUND Little is known about how maternal zinc intake influences growth in utero and in postnatal life in humans . OBJECTIVE We aim ed to assess the effect of maternal zinc supplementation during pregnancy on infant growth through age 1 y. DESIGN A double-blind , r and omized controlled trial of prenatal zinc supplementation was conducted from 1995 to 1997 in Lima , Peru . Women ( n = 1295 ) were enrolled at 15.6 + /- 4.6 wk gestation and assigned to receive daily supplements with zinc ( 15 mg Zn + 60 mg Fe + 250 microg folic acid ) or without zinc ( 60 Fe + 250 microg folic acid ) through pregnancy to 1 mo after delivery . At birth , 546 infants were followed for 12 mo to assess growth . Anthropometric measures of body size and composition were collected monthly , and morbidity and dietary intake surveillance was carried out weekly . RESULTS No differences in maternal socioeconomic characteristics by treatment group or follow-up period were found . Infants born to mothers prenatally supplemented with zinc had significantly ( P < 0.05 ) larger average growth measures beginning in month 4 and continuing through month 12 . In longitudinal regression modeling , prenatal zinc was associated with greater weight ( by 0.58 + /- 0.12 kg ; P < 0.001 ) , calf circumference ( by 1.01 + /- 0.21 cm ; P < 0.001 ) , chest circumference ( by 0.60 + /- 0.20 cm ; P = 0.002 ) , and calf muscle area ( by 35.78 + /- 14.75 mm(2 ) ; P = 0.01 ) after adjustment for a range of covariates . No effect was observed for linear growth . CONCLUSION Maternal zinc supplementation in this population was associated with offspring growth , which is suggestive of lean tissue mass accretion BACKGROUND There is a major increase in endogenous zinc excretion , specifically via the mammary gl and , in early human lactation . Whereas fractional absorption of dietary zinc has been reported to increase in early human lactation , it is not known to what extent adaptive mechanisms may maintain zinc homeostasis , especially when dietary zinc intake is relatively low . OBJECTIVE The objective of this study was to quantitate major variables of zinc homeostasis during early lactation in subjects from a population whose habitual dietary zinc intake is low . DESIGN We studied 18 free-living lactating women from a rural community of northeast China whose infants were exclusively breast-fed .  The subjects were studied at approximately 2 mo of lactation with use of stable isotopes of zinc and metabolic collection techniques .  Milk volume was measured with use of a deuterium enrichment method . RESULTS The mean ( + /-SD ) secretion of zinc in milk was 2.01 + /- 0.97 mg/d , the intake of zinc was 7.64 + /- 1.61 mg/d , and the fractional absorption of zinc was 0.53 + /- 0.09 , for a total daily zinc absorption of 4.00 + /- 0.71 mg/d . Endogenous zinc excretion in urine and feces was 0.30 + /- 0.10 and 1.66 + /- 0.97 mg/d , respectively . CONCLUSIONS Zinc balance , including zinc secreted in breast milk , was maintained at approximately 2 mo of lactation in women whose habitual diet was low in zinc . Homeostasis was achieved by high fractional absorption of zinc and intestinal conservation of endogenous fecal zinc Dietary zinc ( Zn ) intake and selected biochemical indices of Zn status were studied longitudinally at monthly intervals in 46 pregnant middle-income women , 10 of whom received a daily supplement of 15 mg Zn .  Mean dietary Zn intake for the nonsupplemented subjects ( group A ) was 11.3 + /- 4 
    Output:
    