***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 —Moderate red wine consumption is inversely associated with coronary ischemia , and both red wine and purple grape juice ( PGJ ) contain flavonoids with antioxidant and antiplatelet properties believed to be protective against cardiovascular events . Acute cardiac events are also associated with decreased platelet-derived nitric oxide ( NO ) release . In this study , the effects of PGJ and PGJ-derived flavonoids on platelet function and platelet NO production were determined . Methods and Results —Incubation of platelets with dilute PGJ led to inhibition of aggregation , enhanced release of platelet-derived NO , and decreased superoxide production . To confirm the in vivo relevance of these findings , 20 healthy subjects consumed 7 mL · kg−1 · d−1 of PGJ for 14 days . Platelet aggregation was inhibited after PGJ supplementation , platelet-derived NO production increased from 3.5±1.2 to 6.0±1.5 pmol/108 platelets , and superoxide release decreased from 29.5±5.0 to 19.2±3.1 arbitrary units ( P < 0.007 and P < 0.05 , respectively ) . & agr;-Tocopherol levels increased significantly after PGJ consumption ( from 15.6±0.7 to 17.6±0.9 & mgr;mol/L;P < 0.009 ) , and the plasma protein – independent antioxidant activity increased by 50.0 % ( P < 0.05 ) . Last , incubation of platelets with select flavonoid fractions isolated from PGJ consistently attenuated superoxide levels but had variable effects on whole-blood aggregation , platelet aggregation , and NO release . Conclusions —Both in vitro incubation and oral supplementation with PGJ  decrease platelet aggregation , increase platelet-derived NO release , and decrease superoxide production . These findings may be a result of antioxidant-sparing and /or direct effects of select flavonoids found in PGJ . The suppression of platelet-mediated thrombosis represents a potential mechanism for the beneficial effects of purple grape products , independent of alcohol consumption , in cardiovascular disease Summary . Background : Bioavailability of β-carotene is highly variable and depends on the source , the formulation and other nutritional factors . Objective : It was the aim of the study to compare β-carotene plasma response to b-carotene dosing with two commercially available drinks , containing β-carotene from carrot juice or as water dispersible β-carotene powder . Design In a r and omized , parallel group study design , 4 volunteers per group received daily β-carotene doses of 6–7 or 18–22 mg of either drink over 6 weeks . Blood sample s for determination of carotenoid and vitamin A plasma concentrations were collected before supplementation and over the dosing period . Results : Apparent steady-state β-carotene concentrations were attained after 40 days of supplementation . Consumption of the beverage containing β-carotene as a water dispersible powder result ed in a higher response of β-carotene plasma concentrations with increments of 3.84 ± 0.60 μmol/L ( p < 0.05 , dose : 7.2 mg/d ) and 5.04 ± 0.72 μmol/L ( p < 0.05 , dose : 21.6 mg/d ) , respectively , in comparison to the carrot juice-based drink with increments of 0.42 ± 0.33 μmol/L ( dose : 6 mg/d ) and 1.71 ± 0.55 μmol/L ( dose : 18 mg/d ) , respectively . β-carotene was cleared from the plasma with an apparent half-life of 6–11 days . Plasma concentrations of α-carotene , β-cryptoxanthin , lutein , zeaxanthin , and lycopene remained almost unchanged , whereas retinol plasma concentrations increased slightly . By contrast , with the exception of elevated 13-cis-retinoic acid in one group ( 21.6 mg/d , water dispersible powder ) , the concentrations of all-trans-retinoic acid , and the oxo-derivatives or retinoic acid were not significantly affected by b-carotene supplementation . Conclusions : The results confirm that the relative bioavailability of β-carotene depends largely on the source of b-carotene and demonstrate the superior bioavailability of β-carotene powder in comparison to that in carrot juice Background : There is a need for objective and universally applicable biomarkers for the intake of foods believed to affect human health . Objective : The purpose of this feeding study was to test whether plasma concentrations of carotenoids could be used to distinguish recommended consumption of mixed fruits and vegetables ( five a day ) from the current national intake of fruits and vegetables ( two a day ) . Design : A strict crossover design was chosen to correct for observed interindividual variations in carotenoid response . A total of 40 healthy subjects were included in the study . After 1 week run-in period with no fruits and vegetables in the diet , one group was given two portions ( 300 g ) of fruits and vegetables daily , while another group was given five portions ( 750 g ) for 14 days . Following a 2 week wash-out period and 1 week run-in , the regimens were switched between the groups . Fruits and vegetables were combined to match a typical Norwegian diet . Results : Enhanced intake from two to five portions of mixed fruits and vegetables  increased plasma concentrations of α-carotene ( P=0.033 ) and lutein ( P=0.051 ) in a crossover analysis . Analysis of data in the parallel part of the study revealed differences between the high and low intake for plasma concentrations of α-carotene ( P=0.013 ) and β-carotene ( P=0.016 ) . A trend was also evident for plasma concentrations of lycopene ( P=0.057 ) and lutein ( P=0.076 ) in the parallel analysis . No effect of high vs low intake of fruits and vegetables was observed for plasma concentrations of β-cryptoxanthin , zeaxanthin , cholesterol and triacylglycerols . Conclusion : The study indicates that plasma concentration of α-carotene , β-carotene and lutein may be used to assess changes of fruit and vegetable intake corresponding to an increase from the present national intake in Norway to the recommended amount of five portions of fruits and vegetables daily . Sponsorship : Norwegian Research Council , National Nutrition Council , Throne Holst Foundation for Nutrition Research and Freia Chokoladefabriks Medisinske Fond In several epidemiological studies , high intakes of fruits and vegetables have been associated with a lower incidence of cancer . Theoretically , intake of antioxidants by consumption of fruits and vegetables should protect against reactive oxygen species and decrease the formation of oxidative DNA damage . We set up a parallel 24-day dietary placebo-controlled intervention study in which 43 subjects were r and omized into three groups receiving an antioxidant-free basal diet and 600 g of fruits and vegetables , or a supplement containing the corresponding amounts of vitamins and minerals , or placebo .  Blood and urine sample s were collected before , once a week , and 4 weeks after the intervention period . The level of str and breaks , endonuclease III sites , formamidopyrimidine sites , and sensitivity to hydrogen peroxide was assessed in mononuclear blood cells by the comet assay . Excretion of 7-hydro-8-oxo-2'-deoxyguanine was measured in urine . The expressions of oxoguanine glycosylase 1 and excision repair cross complementing 1 DNA repair genes , determined by real-time reverse transcription-PCR of mRNAs , were investigated in leukocytes . Consumption of fruits and vegetables or vitamins and minerals had no effect on oxidative DNA damage measured in mononuclear cell DNA or urine . Hydrogen peroxide sensitivity , detected by the comet assay , did not differ between the groups . Expression of excision repair cross complementing 1 and oxoguanine glycosylase 1 in leukocytes was not related to the diet consumed . Our results show that after 24 days of complete depletion of fruits and vegetables , or daily ingestion of 600 g of fruit and vegetables , or the corresponding amount of vitamins and minerals , the level of oxidative DNA damage was unchanged . This suggests that the inherent antioxidant defense mechanisms are sufficient to protect circulating mononuclear blood cells from reactive oxygen species Background — Observational evidence has consistently linked increased fruit and vegetable consumption with reduced cardiovascular morbidity ; however , there is little direct trial evidence to support the concept that fruit and vegetable consumption improves vascular function . This study assessed the dose-dependent effects of a fruit and vegetable intervention on arterial health in subjects with hypertension . Methods and Results — After a 4-week run-in period during which fruit and vegetable intake was limited to 1 portion per day , participants were r and omized to consume either 1 , 3 , or 6 portions daily for the next 8 weeks . Endothelium-dependent and -independent arterial vasodilator responses were assessed by venous occlusion plethysmography in the brachial circulation before and after intervention . Compliance was monitored with serial contemporaneous 4-day food records and by measuring concentrations of circulating dietary biomarkers . A total of 117 volunteers completed the 12-week study . Participants in the 1- , 3- , and 6-portions/d groups reported consuming on average 1.1 , 3.2 , and 5.6 portions of fruit and vegetables , respectively , and serum concentrations of lutein and & bgr;-cryptoxanthin increased across the groups in a dose-dependent manner . For each 1-portion increase in reported fruit and vegetable consumption , there was a 6.2 % improvement in forearm blood flow responses to intra-arterial administration of the endothelium-dependent vasodilator acetylcholine ( P=0.03 ) . There was no association between increased fruit and vegetable consumption and vasodilator responses to sodium nitroprusside , an endothelium-independent vasodilator . Conclusions — The present study illustrates that among hypertensive volunteers , increased fruit and vegetable consumption produces significant improvements in an established marker of endothelial function and cardiovascular prognosis BACKGROUND Lutein is a hydroxy-carotenoid constituting the macular pigment of the human retina . Increasing lutein intake from foods could increase the density of this pigment and decrease the risk of developing macular degeneration . Yellow carrots are a novel food source that could increase lutein consumption . OBJECTIVE We evaluated and compared lutein uptake and clearance in humans from genetically selected lutein-containing yellow carrots fed chronically and from a lutein supplement . DESIGN Four women and 5 men aged 23 - 28 y participated in this r and omized , blinded , 3 x 3 crossover intervention . Treatments consisted of yellow carrots ( YC treatment , 1.7 mg lutein/d ) , white carrots as a negative control ( WC treatment , 0 mg lutein/d ) , and a lutein supplement in oil as a positive control ( LS treatment , 1.7 mg lutein/d ) . Each treatment lasted 7 d and was followed by a 7-d washout period . RESULTS Mean ( + /- SD ) peak changes in serum lutein concentration from baseline were 0.31 + /- 0.08 , 0.19 + /- 0.08 , and -0.04 + /- 0.04 micromol/L for the LS , YC , and WC treatments , respectively . The areas under the curve for 0 - 14 d ( AUC(0 - 14d ) ) differed significantly ( P < 0.0001 ) between treatments . Lutein from the YC treatment was 65 % as bioavailable as that from the LS treatment . The AUC(0 - 14d ) for beta-carotene ( -0.01 + /- 0.28 micromol.d/L ) also showed that the YC treatment maintained peak serum beta-carotene concentrations at 0.35 + /- 0.30 micromol/L , whereas the LS treatment did not ( AUC(0 - 14d ) = -0.71 + /- 0.59 micromol.d/L ) . CONCLUSION Lutein from this novel food source significantly increases serum lutein concentrations and does not result in the decrease in beta-carotene concentrations that accompanies administration of lutein supplements To determine the effects of vitamin C on cardiovascular risk factors , we studied dietary vitamin C enrichment in 36 healthy male students consuming a diet high in saturated fatty acids . After a 1-mo run-in period during which the subjects consumed approximately 50 mg ascorbic acid/d ( low-C diet ) , half of the subjects were r and omly assigned to receive 500 mg ascorbic acid/d for an additional 2 mo ( high-C diet ) . Plasma ascorbic acid increased from 13.5 micromol/L with the low-C diet to 51.7 micromol/L with the high-C diet . Plasma cholesterol increased slightly with the high-C diet , but not above baseline concentrations . 
    Output:
    
The only possible exception to this is “ fruit only ” intervention studies where assessment of vitamin C alone may suffice