***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: As a follow-up of our study of pregnant women , we report effects of zinc supplementation during pregnancy in another population of 138 Hispanic teenagers in Los Angeles . Teenagers were r and omized ( double-blind ) to a control or zinc-supplemented group and received similar daily vitamin and mineral supplements except for 20 mg zinc added to the zinc-supplemented group 's capsules . Initially , mean dietary zinc intakes of both groups were about 50 % of the Recommended Dietary Allowance and their mean serum zinc levels did not differ significantly ( 69.8 + /- 11.2 micrograms/dl in control and 69.0 + /- 11.4 micrograms/dl in zinc-supplemented group ) . Zinc supplementation did not maintain mean serum zinc levels during pregnancy but , as in our earlier study , it reduced ( p = 0.018 ) the number of low serum zinc values ( less than or equal to 53 micrograms/dl ) in late pregnancy . Zinc supplementation did not affect outcome of pregnancy but serum zinc levels were lower ( p = 0.038 ) in teenagers with pregnancy-induced hypertension than in normotensives The search for a reliable , convenient indicator of Zn status was the focus of research for several decades . Plasma Zn concentration is still the most widely used clinical measurement , despite the known problems of interpretation . More recently , research ers suggested that isotopically determined kinetic parameters , such as the exchangeable Zn pool ( EZP ) , may more accurately and reliably reflect body Zn status . The objective of this study was to examine the relationship between net body Zn loss and gain during acute changes in dietary Zn intake with biochemical and kinetic indices of Zn status . Five men participated in an 85-d Zn depletion/repletion study .  Net body Zn loss and gain were determined from the difference between dietary plus intravenously administered Zn and Zn excretion . Biochemical indicators of Zn status included plasma Zn , plasma alkaline phosphatase activity , and plasma retinol binding protein concentration . Following intravenous administration of (70)Zn or (67)Zn , a compartmental model was used to determine EZP mass , fractional Zn absorption , endogenous zinc excretion ( EZE ) , and plasma Zn flux . The changes in total body zinc correlated best with changes in plasma Zn ( r(2 ) = 0.826 , P < 0.001 ) , EZE ( r(2 ) = 0.773 , P < 0.001 ) , and plasma Zn flux ( r(2 ) = 0.766 , P < 0.001 ) . This study confirms that plasma Zn concentration is a valid indicator of whole-body Zn status in the absence of confounding factors ; however , further research is needed to determine how kinetic parameters respond to conditions where plasma Zn concentration is known to be unreliable One hundred and three apparently healthy elderly subjects age 60 - 89 y were r and omly assigned to one of three treatments : placebo , 15 mg zinc/d , or 100 mg Zn/d for 3 mo . Plasma Zn was significantly increased only in the 100 mg Zn group . Zn concentrations in erythrocytes , platelets , mononuclear cells , and polymorphonuclear leukocytes were not significantly increased by any treatment . None of the treatments significantly altered delayed dermal hypersensitivity ( DDH ) to a panel of seven recall antigens or in vitro lymphocyte proliferative responses ( LPR ) to mitogens and antigens . Fifteen subjects had initially poor lymphocyte proliferative responses that improved in 14 of these individuals during the study ; this was not due to Zn supplementation but might have been caused by one or more components of a vitamin-mineral supplement administered to all study subjects Although immunity is impaired during severe zinc deficiency , there is limited information about the effects of mild zinc depletion on immune response in humans . We evaluated the effects of a zinc-restricted diet ( 4.6 mg/d ) on several indices of immunity in 8 healthy men . The subjects consumed zinc supplements with 9.1 mg/d during the 5-wk baseline ( BL ) and 5-wk repletion ( RP ) periods , and placebos during the 10-wk zinc-restriction ( ZR ) period . Leukocyte numbers and functions were studied at the end of each metabolic period . After ZR , there were reductions in the proliferation of peripheral blood mononuclear cells ( PBMNC ) stimulated with phytohemagglutinin ( PHA , 1.2 , 2.5 , 5.0 , 10.0 [ corrected ] and 20.0 mg/L ; P < 0.01 ) and in the in vitro secretion of interleukin-2 receptor ( IL-2R ) ( PHA , 2.5 mg/L ; P = 0.058 ) . These variables remained reduced ( P < 0.05 ) even after 5 wk of zinc repletion . The amount of zinc consumed did not alter the numbers of circulating neutrophils , monocytes and lymphocytes , the in vitro PBMNC secretion of interferon-gamma and tumor necrosis factor-alpha or neutrophil superoxide production . The results suggest that changes in lymphocyte proliferation and IL-2R expression may be early markers of mild zinc deficiency 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 Zinc and iron compete during intestinal absorption , but postabsorptive interactions between these nutrients are less clear . Underst and ing these interactions is important to determine when supplementation with iron or zinc is proposed . The effect of zinc supplementation ( 22 mg Zn/d as zinc gluconate ) or of iron supplementation ( 100 mg Fe/d as ferrous sulfate ) for 6 wk on iron and zinc metabolism and absorption was evaluated in young women with low iron reserves . Young adult women ( ages 20 - 28 y ) , nonanemic but with low iron stores ( plasma ferritin < 20 microg/L ) , participated in the 70-d study . The women were divided in two groups ( zinc-supplemented , n = 11 ; iron-supplemented , n = 12 ) . The supplements were taken at bedtime .  Iron and zinc biochemical indices and intestinal absorption were measured on d 1 and 56 .  Radioiron and stable isotopes of zinc  were used to measure iron and zinc absorption from a test meal . In the iron-supplemented group , blood hemoglobin , plasma ferritin and the percentage of transferrin saturation increased ( P < 0.01 ) . Zinc indices did not change . In the zinc-supplemented group , plasma ferritin and the percentage of transferrin saturation decreased ( P < 0.05 ) , whereas the plasma transferrin receptor and erythrocyte zinc protoprophyrin levels increased ( P < 0.05 ) . Plasma and urinary zinc also increased ( P < 0.01 ) . Iron absorption ( % ) from the test meal increased ( P < 0.01 ) , whereas zinc absorption ( % ) decreased ( P < 0.01 ) compared with baseline in the Zn-supplemented women . Our results indicate that the use of iron supplements in women with marginal iron status improves iron indices with no effect on zinc status . However , use of a modest zinc supplement improves zinc indices , but also appears to induce a cellular iron deficiency and , possibly , further reduce iron status The zinc status of 53 healthy elderly subjects was evaluated . The dietary Zn intake estimated by 24-h recall was 9.2 mg/d and 65 % of subjects had intakes less than two-thirds of the RDA . Mean serum Zn concentration ( 13.0 mumol/L ) and urinary Zn excretion ( 7.0 mumol/d ) were normal . The Zn content of platelets , mononuclear cells , and polymorphonuclear cells was 5.8 , 147 , and 135 nmol/10(9 ) cells , respectively . Seventeen subjects were supplemented for 28 d with 30 mg Zn/d . The mean concentration of Zn in serum and urine increased 24 % and 2.5-fold , respectively . Zn content of platelets and leukocytes did not change with Zn supplementation . The concentration of visceral proteins ( ie , albumin , prealbumin , transferrin , and retinol-binding protein ) and immunoglobulins ( ie , IgG , IgA , and IgM ) did not change with Zn supplementation . The data indicate that aging per se does not necessarily imply poor Zn status A 12-wk double-blind study was conducted to determine the effect of oral zinc supplementation upon serum total cholesterol , lipoprotein-cholesterol fractions , and serum triglycerides in white males . The subjects were r and omly assigned to one of three treatment groups and consumed either a placebo tablet ( n = 9 ) , 50 mg Zn/d ( n = 13 ) , or 75 mg Zn/d ( n = 9 ) as Zn gluconate .  Serum total cholesterol , low-density-lipoprotein ( LDL ) cholesterol , very-low-density-lipoprotein ( VLDL ) cholesterol , and triglycerides were not affected by Zn supplements . However , serum high-density-lipoprotein (HDL)-cholesterol levels in subjects assigned to the 75 mg Zn/d group were significantly lower at weeks 6 and 12 than those for the placebo group and lower at weeks 6 , 8 , and 12 than at baseline ; subjects assigned to the 50 mg Zn/d group had lower serum HDL-cholesterol levels at week 12 than did the placebo group and lower at week 12 than at base line The effects of zinc supplementation on the copper status of healthy adult men , as assessed by the activities of the copper-metalloenzymes , plasma ferroxidase ( ceruloplasmin ) , and erythrocyte Cu , Zn-superoxide dismutase , were determined . The subjects were given either two daily doses of 25 mg zinc or placebo for 6 wk . No significant differences in the plasma copper levels or the ferroxidase activities between the supplemented and control groups could be detected at 2 , 4 , or 6 wk . Plasma zinc increased and erythrocyte Cu , Zn-superoxide dismutase decreased in the supplemented group , the difference between the groups becoming significant at 6 wk ( p less than 0.05 ) . This suggested that the zinc supplements decreased the copper status of the experimental group The effects of zinc supplementation on zinc status and on clinical and biological indicators of inflammation were investigated in 18 patients with chronic inflammatory rheumatic diseases and in 9 healthy control subjects . Patients with mild and recent onset disease were assigned to a 60-d trial to receive either 45 mg Zn ( as gluconate)/d or a placebo , while control subjects received the zinc supplement .  Baseline mean plasma zinc of the patients was low whereas mononuclear cell zinc content was elevated , suggesting a redistribution of the element related to the inflammatory process rather than to a zinc-deficient state . Zinc supplementation increased plasma zinc to a similar extent in patients and in control subjects , which suggested no impairment of zinc intestinal absorption as a result of the inflammatory process . On the contrary , erythrocyte and leukocyte zinc concentrations were not modified in the two groups examined . No beneficial effect of zinc treatment could be demonstrated on either clinical or inflammation indexes In the treatment of dysgeusia , the use of zinc has been frequently tried , with equivocal results . The aim of the present r and omized clinical trial , which involved a sufficiently large sample , was therefore to determine the efficacy of zinc treatment . Fifty patients with idiopathic dysgeusia were carefully selected .  Zinc gluconate ( 140 mg/day ; n = 26 ) or placebo ( lactose ; n = 24 ) was r and omly assigned to the patients . The patients on zinc improved in terms of gustatory function ( p < 0.001 ) and rated the dysgeusia as being less severe ( p < 0.05 ) 
    Output:
    
Urinary zinc excretion responded to zinc status overall and in all subgroups for which there were sufficient data .
Hair zinc concentration also responded , but there were insufficient studies for subgroup analysis .
Platelet , polymorphonuclear cell , mononuclear cell , and erythrocyte zinc concentration and alkaline phosphatase activity did not appear to be effective biomarkers of zinc status .
This systematic review confirms that in healthy individuals , plasma , urinary , and hair zinc are reliable biomarkers of zinc status .