***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: Evidence suggests that flavonoid-containing diets reduce cardiovascular risk , but the mechanisms responsible are unclear . In the present study , we sought to determine the effect of flavanol-rich cocoa on vascular function in individuals with CAD ( coronary artery disease ) . Forty subjects ( 61+/-8 years ; 30 male ) with CAD were recruited to a 6-week r and omized double-blind placebo-controlled study . Subjects consumed either a flavanol-rich chocolate bar and cocoa beverage daily ( total flavanols , 444 mg/day ) or matching isocaloric placebos daily ( total flavanols , 19.6 mg/day ) for 6 weeks . Brachial artery FMD ( flow-mediated dilation ) and SAC ( systemic arterial compliance ) were assessed at baseline , 90 min following the first beverage and after 3 and 6 weeks of daily consumption . Soluble cellular adhesion molecules and FBF ( forearm blood flow ) responses to ACh ( acetylcholine chloride ; 3 - 30 microg/min ) and SNP ( sodium nitroprusside ; 0.3 - 3 microg/min ) infusions , forearm ischaemia and isotonic forearm exercise were assessed at baseline and after 6 weeks . FMD , SAC and FBF responses did not differ between groups at baseline . No acute or chronic changes in FMD or SAC were seen in either group . No difference in soluble cellular adhesion molecules , FBF responses to ischaemia , exercise , SNP or ACh was seen in the group receiving flavanol-rich cocoa between baseline and 6 weeks . These data suggest that over a 6-week period , flavanol-rich cocoa does not modify vascular function in patients with established CAD Background Consumption of chocolate has been often hypothesized to reduce the risk of cardiovascular disease ( CVD ) due to chocolate 's high levels of stearic acid and antioxidant flavonoids . However , debate still lingers regarding the true long term beneficial cardiovascular effects of chocolate overall . Methods We review ed English- language MEDLINE publications from 1966 through January 2005 for experimental , observational , and clinical studies of relations between cocoa , cacao , chocolate , stearic acid , flavonoids ( including flavonols , flavanols , catechins , epicatechins , and procynadins ) and the risk of cardiovascular disease ( coronary heart disease ( CHD ) , stroke ) . A total of 136 publications were selected based on relevance , and quality of design and methods . An up date d meta- analysis of flavonoid intake and CHD mortality was also conducted . Results The body of short-term r and omized feeding trials suggests cocoa and chocolate may exert beneficial effects on cardiovascular risk via effects on lowering blood pressure , anti-inflammation , anti-platelet function , higher HDL , decreased LDL oxidation . Additionally , a large body of trials of stearic acid suggests it is indeed cholesterol-neutral . However , epidemiologic studies of serum and dietary stearic acid are inconclusive due to many method ologic limitations . Meanwhile , the large body of prospect i ve studies of flavonoids suggests the flavonoid content of chocolate may reduce risk of cardiovascular mortality . Our up date d meta- analysis indicates that intake of flavonoids may lower risk of CHD mortality , RR = 0.81 ( 95 % CI : 0.71–0.92 ) comparing highest and lowest tertiles . Conclusion Multiple lines of evidence from laboratory experiments and r and omized trials suggest stearic acid may be neutral , while flavonoids are likely protective against CHD mortality . The highest priority now is to conduct larger r and omized trials to definitively investigate the impact of chocolate consumption on long-term cardiovascular outcomes Consumption of flavanol-rich dark chocolate ( DC ) has been shown to decrease blood pressure ( BP ) and insulin resistance in healthy subjects , suggesting similar benefits in patients with essential hypertension ( EH ) . Therefore , we tested the effect of DC on 24-hour ambulatory BP , flow-mediated dilation ( FMD ) , and oral glucose tolerance tests ( OGTTs ) in patients with EH . After a 7-day chocolate-free run-in phase , 20 never-treated , grade I patients with EH ( 10 males ; 43.7±7.8 years ) were r and omized to receive either 100 g per day DC ( containing 88 mg flavanols ) or 90 g per day flavanol-free white chocolate ( WC ) in an isocaloric manner for 15 days . After a second 7-day chocolate-free period , patients were crossed over to the other  treatment . Noninvasive 24-hour ambulatory BP , FMD , OGTT , serum cholesterol , and markers of vascular inflammation were evaluated at the end of each treatment . The homeostasis model assessment of insulin resistance ( HOMA-IR ) , quantitative insulin sensitivity check index ( QUICKI ) , and insulin sensitivity index ( ISI ) were calculated from OGTT values . Ambulatory BP decreased  after DC ( 24-hour systolic BP −11.9±7.7 mm Hg , P<0.0001 ; 24-hour diastolic BP −8.5±5.0 mm Hg , P<0.0001 ) but not WC . DC but not WC decreased HOMA-IR ( P<0.0001 ) , but it improved QUICKI , ISI , and FMD . DC also decreased serum LDL cholesterol ( from 3.4±0.5 to 3.0±0.6 mmol/L ; P<0.05 ) . In  summary , DC  decreased BP and serum LDL cholesterol , improved FMD , and ameliorated insulin sensitivity in hypertensives . These results suggest that , while balancing total calorie intake , flavanols from cocoa products may provide some cardiovascular benefit if included as part of a healthy diet for patients with EH BACKGROUND Studies suggest cardioprotective benefits of dark chocolate containing cocoa . OBJECTIVE This study examines the acute effects of solid dark chocolate and liquid cocoa intake on endothelial function and blood pressure in overweight adults . DESIGN R and omized , placebo-controlled , single-blind crossover trial of 45 healthy adults [ mean age : 53 y ; mean body mass index ( in kg/m(2 ) ) : 30 ] . In phase 1 , subjects were r and omly assigned to consume a solid dark chocolate bar ( containing 22 g cocoa powder ) or a cocoa-free placebo bar ( containing 0 g cocoa powder ) . In phase 2 , subjects were r and omly assigned to consume sugar-free cocoa ( containing 22 g cocoa powder ) , sugared cocoa ( containing 22 g cocoa powder ) , or a placebo ( containing 0 g cocoa powder ) . RESULTS Solid dark chocolate and liquid cocoa ingestion improved endothelial function ( measured as flow-mediated dilatation ) compared with placebo ( dark chocolate : 4.3 + /- 3.4 % compared with -1.8 + /- 3.3 % ; P < 0.001 ; sugar-free and sugared cocoa : 5.7 + /- 2.6 % and 2.0 + /- 1.8 % compared with -1.5 + /- 2.8 % ; P < 0.001 ) . Blood pressure decreased after the ingestion of dark chocolate and sugar-free cocoa compared with placebo ( dark chocolate : systolic , -3.2 + /- 5.8 mm Hg compared with 2.7 + /- 6.6 mm Hg ; P < 0.001 ; and diastolic , -1.4 + /- 3.9 mm Hg compared with 2.7 + /- 6.4 mm Hg ; P = 0.01 ; sugar-free cocoa : systolic , -2.1 + /- 7.0 mm Hg compared with 3.2 + /- 5.6 mm Hg ; P < 0.001 ; and diastolic : -1.2 + /- 8.7 mm Hg compared with 2.8 + /- 5.6 mm Hg ; P = 0.014 ) . Endothelial function improved significantly more with sugar-free than with regular cocoa ( 5.7 + /- 2.6 % compared with 2.0 + /- 1.8 % ; P < 0.001 ) . CONCLUSIONS The acute ingestion of both solid dark chocolate and liquid cocoa  improved endothelial function and lowered blood pressure  in overweight adults . Sugar content may attenuate these effects , and sugar-free preparations may augment them BACKGROUND Numerous studies indicate that flavanols may exert significant vascular protection because of their antioxidant properties and increased nitric oxide bioavailability . In turn , nitric oxide bioavailability deeply influences insulin-stimulated glucose uptake and vascular tone . Thus , flavanols may also exert positive metabolic and pressor effects . OBJECTIVE The objective was to compare the effects of either dark or white chocolate bars on blood pressure and glucose and insulin responses to an oral-glucose-tolerance test in healthy subjects . DESIGN After a 7-d cocoa-free run-in phase , 15 healthy subjects were r and omly assigned to receive for 15 d either 100 g dark chocolate bars , which contained approximately 500 mg polyphenols , or 90 g white chocolate bars , which presumably contained no polyphenols . Successively , subjects entered a further cocoa-free washout phase of 7 d and then were crossed over to the other condition . Oral-glucose-tolerance tests were performed at the end of each period to calculate the homeostasis model assessment of insulin resistance ( HOMA-IR ) and the quantitative insulin sensitivity check index ( QUICKI ) ; blood pressure was measured daily . RESULTS HOMA-IR was significantly lower after dark than after white chocolate ingestion ( 0.94 + /- 0.42 compared with 1.72 + /- 0.62 ; P < 0.001 ) , and QUICKI was significantly higher after dark than after white chocolate ingestion ( 0.398 + /- 0.039 compared with 0356 + /- 0.023 ; P = 0.001 ) . Although within normal values , systolic blood pressure was lower after dark than after white chocolate ingestion ( 107.5 + /- 8.6 compared with 113.9 + /- 8.4 mm Hg ; P < 0.05 ) . CONCLUSION Dark , but not white , chocolate decreases blood pressure and improves insulin sensitivity in healthy persons Cocoa powder is rich in polyphenols , such as catechins and procyanidins , and has been shown in a variety of subject models to inhibit oxidized LDL and atherogenesis . Our study evaluated plasma LDL cholesterol and oxidized LDL concentrations following the intake of different levels of cocoa powder ( 13 , 19.5 , and 26 g/d ) in normocholesterolemic and mildly hypercholesterolemic humans . In this comparative , double-blind study , we examined 160 subjects who ingested either cocoa powder containing low-polyphenolic compounds ( placebo-cocoa group ) or 3 levels of cocoa powder containing high-polyphenolic compounds ( 13 , 19.5 , and 26 g/d for low- , middle- , and high-cocoa groups , respectively ) for 4 wk . The test powders were consumed as a beverage after the addition of hot water , twice each day . Blood sample s were collected at baseline and 4 wk after intake of the test beverages for the measurement of plasma lipids . Plasma oxidized LDL concentrations decreased in the low- , middle- , and high-cocoa groups compared with baseline . A stratified analysis was performed on 131 subjects who had a LDL cholesterol concentrations of > or = 3.23 mmol/L at baseline . In these subjects , plasma LDL cholesterol , oxidized LDL , and apo B concentrations decreased , and the plasma HDL cholesterol concentration increased , relative to baseline in the low- , middle- , and high-cocoa groups . The results suggest that polyphenolic substances derived from cocoa powder may contribute to a reduction in LDL cholesterol , an elevation in HDL cholesterol , and the suppression of oxidized LDL Flavanols from chocolate appear to increase nitric oxide bioavailability , protect vascular endothelium , and decrease cardiovascular disease ( CVD ) risk factors . We sought to test the effect of flavanol-rich dark chocolate ( FRDC ) on endothelial function , insulin sensitivity , beta-cell function , and blood pressure ( BP ) in hypertensive patients with impaired glucose tolerance ( IGT ) . After a run-in phase , 19 hypertensives with IGT ( 11 males , 8 females ; 44.8 + /- 8.0 y ) were r and omized to receive isocalorically either FRDC or flavanol-free white chocolate ( FFWC ) at 100 g/d for 15 d. After a wash-out period , patients were switched to the other treatment . Clinical and 24-h ambulatory BP was determined by sphygmometry and oscillometry , respectively , flow-mediated dilation ( FMD ) , oral glucose tolerance test , serum chol 
    Output:
    
Chocolate or cocoa  improved FMD regardless of the dose consumed , whereas doses > 50 mg epicatechin/d result ed in greater effects on systolic and diastolic BP .
GRADE ( Grading of Recommendations , Assessment , Development and Evaluation , a tool to assess quality of evidence and strength of recommendations ) suggested low- to moderate- quality evidence of beneficial effects , with no suggestion of negative effects .
We found consistent acute and chronic benefits of chocolate or cocoa on FMD and previously unreported promising effects on insulin and HOMA-IR .