***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: In the elderly , immunosenescence and malnourishment can contribute to increased risk and severity of upper respiratory tract infections ( URTI ) . Gold kiwifruit ( Actinidia chinensis ' Hort16A ' ) contains nutrients important for immune function and mitigation of symptoms of infection , including vitamins C and E , folate , polyphenols and carotenoids . The objective of the present study was to evaluate whether regular consumption of gold kiwifruit reduces symptoms of URTI  in older people , and determine the effect it has on plasma antioxidants , and markers of oxidative stress , inflammation and immune function . A total of thirty-two community-dwelling people ( ≥65 years ) participated in a r and omised crossover study , consuming the equivalent of four kiwifruit or two bananas daily for 4 weeks , with treatments separated by a 4-week washout period . Participants completed the Wisconsin Upper Respiratory Symptom Survey-21 daily , and blood sample s were collected at baseline and at the end of each treatment and washout period . Gold kiwifruit did not significantly reduce the overall incidence of URTI compared with banana , but significantly reduced the severity and duration of head congestion , and the duration of sore throat . Gold kiwifruit significantly increased plasma vitamin C , α-tocopherol and lutein/zeaxanthin concentrations , and erythrocyte folate concentrations , and significantly reduced plasma lipid peroxidation . No changes to innate immune function ( natural killer cell activity , phagocytosis ) or inflammation markers ( high-sensitivity C-reactive protein , homocysteine ) were detected . Consumption of gold kiwifruit enhanced the concentrations of several dietary plasma analytes , which may contribute to reduced duration and severity of selected URTI symptoms , offering a novel tool for reducing the burden of URTI in older individuals Vitamin E disappearance is accelerated in cigarette smokers due to their increased oxidative stress and is inversely correlated with plasma vitamin C concentrations . Therefore , we hypothesized that ascorbic acid supplementation ( 500 mg , twice daily ; 2 weeks ) would normalize smokers ' plasma alpha- and gamma-tocopherol disappearance rates and conducted a double-blind , placebo-controlled , r and omized crossover investigation in smokers ( n=11 ) and nonsmokers ( n=13 ) given a single dose of deuterium-labeled alpha- and gamma-tocopherols ( 50 mg each d6-RRR-alpha and d2-RRR-gamma-tocopheryl acetate ) . During the placebo trial , smokers , compared with nonsmokers , had significantly ( P<0.05 ) greater alpha- and gamma-tocopherol fractional disappearance rates and shorter half-lives .  Ascorbic acid supplementation doubled ( P<0.0001 ) plasma ascorbic acid concentrations in both groups and attenuated smokers ' , but not nonsmokers ' , plasma alpha- and gamma-tocopherol ( P<0.05 ) fractional disappearance rates by 25 % and 45 % , respectively . Likewise , smokers ' plasma deuterium-labeled alpha- and gamma-tocopherol concentrations were significantly higher ( P<0.05 ) at 72 h during ascorbic acid supplementation compared with placebo . Ascorbic acid supplementation did not significantly change ( P>0.05 ) time of maximal or maximal-labeled alpha- and gamma-tocopherol concentrations . Smokers ' plasma F2alpha-isoprostanes were approximately 26 % higher than nonsmokers ( P>0.05 ) and were not affected by ascorbic acid supplementation in either group ( P>0.05 ) . In summary , cigarette smoking increased plasma alpha- and gamma-tocopherol fractional disappearance rates , suggesting that the oxidative stress from smoking oxidizes tocopherols and that plasma ascorbic acid reduces alpha- and gamma-tocopheroxyl radicals to nonoxidized forms , thereby decreasing vitamin E disappearance in humans In 20 healthy children undergoing elective surgery  , mobility of neutrophils , both unstimulated and stimulated by endotoxin , was studied using a millipore filter system with microscopic determination of leading front migration . Paired sample s were incubated with 10‐2 mol l‐1 calcium ascorbate and ten children also received 10 mg kg‐1 ascorbic acid before premedication . Stimulation of mobility was reduced after the opioid premedication ( P < 0.05 ) in the ascorbate group only , hut not significantly during anaesthesia and surgery . A few individuals showed persisting abnormally low values . No effect of ascorbate  in vivo or in vitro was demonstrated . There were no infrations Abstract . Exercise increases oxygen consumption and causes a disturbance of intracellular pro-oxidant-antioxidant homeostasis . Few data are available as to the cumulative effects of exercise on the antioxidant defenses of the neutrophil . We studied the effects of 90 days ' supplementation with placebo or an antioxidant cocktail of vitamin E ( 500 mg/day ) and β-carotene ( 30 mg/day ) and the last 15 days also with vitamin C ( 1 g/day ) on sportsmen 's basal neutrophil antioxidant defenses . We analyzed the activities of catalase , glutathione peroxidase , glutathione reductase and the activities and levels of superoxide dismutase , glutathione and glutathione disulfide in neutrophils purified from antecubital vein blood of sportsmen before and after  diet supplementation .  Plasma vitamin E , β-carotene and vitamin C concentrations in the antioxidant-supplemented group were approximately 1.6 , 10 , and 1.2 times higher respectively than those of the placebo group . The antioxidant-supplemented group presented a significantly higher glutathione versus glutathione disulfide ratio in neutrophils ( about 20 % ) than the placebo one . Antioxidant supplementation  enhances the antioxidant enzyme activity of superoxide dismutase and catalase in neutrophils BACKGROUND Lack of reliable dietary data has hampered the ability to effectively distinguish between effects of smoking and diet on plasma antioxidant status . As confirmed by analyses of comprehensive food-frequency question naires , the total dietary intakes of fruit and vegetables and of dietary antioxidants were not significantly different between the study groups in the present study , thereby enabling isolation of the effect of smoking . OBJECTIVE Our objective was to investigate the effect of smoking on plasma antioxidant status by measuring ascorbic acid , alpha-tocopherol , gamma-tocopherol , beta-carotene , and lycopene , and subsequently , to test the effect of a 3-mo dietary supplementation with a moderate-dose vitamin cocktail . DESIGN In a double-blind , placebo-controlled design , the effect of a vitamin cocktail containing 272 mg vitamin C , 31 mg all-rac-alpha-tocopheryl acetate , and 400 microg folic acid on plasma antioxidants was determined in a population of smokers ( n = 37 ) and nonsmokers ( n = 38 ) . The population was selected for a low intake of fruit and vegetables and recruited from the San Francisco Bay area . RESULTS Only ascorbic acid was significantly depleted by smoking per se ( P < 0.01 ) . After the 3-mo supplementation period , ascorbic acid was efficiently repleted in smokers ( P < 0.001 ) . Plasma alpha-tocopherol and the ratio of alpha- to gamma-tocopherol increased significantly in both supplemented groups ( P < 0.05 ) . CONCLUSIONS Our data suggest that previous reports of lower concentrations of plasma vitamin E and carotenoids in smokers than in nonsmokers may primarily have been caused by differences in dietary habits between study groups . Plasma ascorbic acid was depleted by smoking and repleted by moderate supplementation Using a reliable , newly developed assay for ascorbic acid ( reduced form ) and dehydroascorbic acid ( DHAA ; the oxidized form ) in plasma , we studied the influence of age , sex , and smoking on 219 healthy , age-stratified , and r and omly selected subjects representing the Danish population . The mean ( + /-SD ) plasma total ascorbic acid ( ascorbic acid + DHAA ) concentration was lower in smokers ( 62.8 + /- 24.9 mumol/L ) than in nonsmokers ( 74.9 + /- 23.6 mumol/L ) ( P < 0.001 ) and the DHAA content was 1.8 + /- 4.0 % of the total ascorbic acid in smokers compared with 0.1 + /- 3.1 % in nonsmokers ( P < 0.001 ) . A significant inverse correlation between the DHAA fraction and the total ascorbic acid concentration was found in smokers ( P < 0.002 ) but not in smokers ; the slopes of the linear regressions were significantly different in the two groups ( P < 0.005 ) . The mean plasma concentration of total ascorbic acid was higher in females than in males ( P < 0.005 ) ; this difference persisted in multivariate analysis when smoking was adjusted for . No age dependence could be identified . The data show that smoking results in severe oxidative stress , depletion of the ascorbic acid pool , and insufficient reduction capacity to maintain ascorbic acid in the reduced form in plasma . We suggest that the additional analysis of DHAA allows further differentiation in the assessment of oxidative stress and may provide an objective way of determining vitamin C requirements in smokers . Preliminary findings suggest that a vitamin C dose that results in a plasma concentration of approximately 70 mumol/L or higher is required in smokers Clinical studies suggest that neutrophil activation during acute myocardial infa rct ion ( MI ) aggravates tissue injury . Activated neutrophils are an important source of oxygen free radicals ( OFR ) , the injurious effects of which are counteracted by endogenous antioxidants . We have previously shown in healthy subjects that supplementation with antioxidant vitamins C and E suppresses OFR production by isolated neutrophils assayed by chemiluminescence ( CL ) . The present study , performed in patients with acute MI aim ed ( 1 ) to investigate the effect of vitamin C and E supplementation upon neutrophil OFR production and serum lipid peroxides , ( 2 ) to evaluate serum levels of vitamins C and E in the course of MI . Forty-five patients with acute MI were r and omized to receive either conventional treatment only ( control  ,  n=22 ) . All measurements were performed on the 1st and 14th day . Neutrophil OFR production assayed by CL decreased significantly in VIT patients ( Wilcoxon test for paired data P<0.01 , Chi square test P<0.01 ) . In the control group , changes in OFR production were not significant . Serum lipid peroxides ( measured as TBARS ) increased in controls ( P<0.05 ) , but remained stable in VIT patients . Mean ( + /-SE ) serum ascorbic acid and tocopherol on the 1st day were 0.43 + /- 0.18 % and 3.25 + /- 1.32 microM.M(-1 ) cholesterol , respectively , in all patients . On the 14th day in non-supplemented patients mean tocopherol was unchanged , whereas ascorbic acid increased significantly ( 0.63 + /- 0.24 mg% , P<0.01 ) suggesting that a low basal level was associated at least in part with the acute phase of the disease . An expected increase in serum vitamin levels occurred in VIT patients . In conclusion , supplementation with vitamins C and E suppresses neutrophil OFR production and lowers the marker of lipid peroxidation in patients with MI The influence of an antioxidant vitamin supplement on immune cell response to prolonged exercise was determined using a r and omized , double-blind , placebo-controlled , cross-over study . Twelve healthy endurance subjects ( n = 6 male , n = 6 female ; mean + /- SD for age , 30.1 + /- 6.2 yr ; height , 1.76 + /- 7 m ; body mass , 72.2 + /- 10.2 kg ; VO2max , 63.7 + /- 12 ml x kg(-1 ) x min(-1 ) ) participated in the study . Following a 3-week period during which subjects ingested a multivitamin and -mineral complex sufficient to meet the recommended daily allowance , they took either a placebo or an antioxidant vitamin supplement ( containing 18 mg beta-carotene , 900 mg vitamin C , and 90 mg vitamin E ) for 7 days prior to a 2-h treadmill run at 65 % VO2max . Blood sample s were drawn prior to and immediately following exercise . These were analyzed for neutrophil oxidative burst activity , cortisol and glucose concentrations , and white blood cell counts , as well as serum anti-oxidant vitamin concentrations . Plasma vitamin C , vitamin E , and beta-carotene concentrations significantly increased following 7-day supplementation ( p < .05 ) . In comparison to the placebo group , neutroph 
    Output:
    
Overall , 44 % of the RCTs assessed in this review showed effects of vitamin C supplementation  on neutrophil functions .