***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 a r and omized , double-blind placebo controlled trial , 63 middle-aged volunteers aged between 40 and 65 years were administered a daily chocolate drink containing 250 mg or 500 mg cocoa flavanols versus a low cocoa flavanol ( placebo ) drink over a 30-day period . Participants were tested at baseline as well as at the end of the treatment period on a test of Spatial Working Memory . Steady State Probe Topography ( SST ) was used to assess neurocognitive changes associated with cocoa flavanol supplementation during the completion of the Spatial Working Memory task . SST is an electrophysiological technique which utilizes a 13 Hz diffuse visual flicker in order to generate a steady state visually evoked potential ( SSVEP ) . Changes in the amplitude and phase of the SSVEP response after 30 days were compared between treatment groups . Behavioral measures of accuracy and reaction time were not found to be significantly different between treatment groups , while average SSVEP amplitude and phase differences at a number of posterior parietal and centro-frontal sites were found to be significantly different between groups during memory encoding , the working memory hold period and retrieval . In the absence of significant behavioral effects , these differences in brain activation can be interpreted as evidence of increased neural efficiency in spatial working memory function associated with chronic cocoa flavanol consumption 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 This is the first experimental study directed at differentiating between physiological or sensory accounts of the satiation of nondrug cravings , using  chocolate craving , the most common craving in North America . At the onset of craving ,  chocolate cravers consumed a chocolate bar , the caloric equivalent in " white chocolate " ( containing none of the pharmacological components of chocolate ) , the pharmacological equivalent in cocoa capsules , placebo , and no treatment conditions had virtually no effect . White chocolate produced partial abatement , unchanged by the addition of all the pharmacological factors in cocoa . This result indicates no role for pharmacological effects in the satisfaction of chocolate craving . It also suggests a role for aroma independent of sweetness , texture , and calories 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 BACKGROUND In recent years , there has been increased interest in the potential health-related benefits of antioxidant- and phytochemical-rich dark chocolate and cocoa . OBJECTIVE The objective of the study was to examine the short-term ( 6 wk ) effects of dark chocolate and cocoa on variables associated with neuropsychological functioning and cardiovascular health in healthy older adults . DESIGN A double-blind , placebo-controlled , fixed-dose , parallel-group clinical trial was used . Participants ( n = 101 ) were r and omly assigned to receive a 37-g dark chocolate bar and 8 ounces ( 237 mL ) of an artificially sweetened cocoa beverage or similar placebo products each day for 6 wk . RESULTS No significant group ( dark chocolate and cocoa or placebo)-by-trial ( baseline , midpoint , and end-of-treatment assessment s ) interactions were found for the neuropsychological , hematological , or blood pressure variables examined . In contrast , the midpoint and end-of-treatment mean pulse rate assessment s in the dark chocolate and cocoa group were significantly higher than those at baseline and significantly higher than the midpoint and end-of-treatment rates in the control group . Results of a follow-up question naire item on the treatment products that participants believed they had consumed during the trial showed that more than half of the participants in both groups correctly identified the products that they had ingested during the experiment . CONCLUSIONS This investigation failed to support the predicted beneficial effects of short-term dark chocolate and cocoa consumption on any of the neuropsychological or cardiovascular health-related variables included in this research . Consumption of dark chocolate and cocoa was , however , associated with significantly higher pulse rates at 3- and 6-wk treatment assessment Cocoa flavanols ( CF ) positively influence physiological processes in ways that suggest their consumption may improve aspects of cognitive function . This study investigated the acute cognitive and subjective effects of CF consumption during sustained mental dem and . In this r and omized , controlled , double-blinded , balanced , three period crossover trial 30 healthy adults consumed drinks containing 520 mg , 994 mg CF and a matched control , with a three-day washout between drinks . Assessment s included the state anxiety inventory and repeated 10-min cycles of a Cognitive Dem and Battery comprising of two serial subtraction tasks ( Serial Threes and Serial Sevens ) , a  Rapid Visual Information Processing ( RVIP ) task and a ‘ mental fatigue ’ scale , over the course of 1 h. Consumption of both 520 mg and 994 mg CF significantly improved Serial Threes performance . The 994 mg CF beverage significantly speeded RVIP responses but also result ed in more errors during Serial Sevens . Increases in self-reported ‘ mental fatigue ’ were significantly attenuated by the consumption of the 520 mg CF beverage only . This is the first report of acute cognitive improvements following CF consumption in healthy adults . While the mechanisms underlying the effects are unknown they may be related to known effects of CF on endothelial function and blood flow Background : Dark chocolate derived from the plant ( Theobroma cacao ) is a rich source of flavonoids . Cardioprotective effects including antioxidant properties , inhibition of platelet activity , and activation of endothelial nitric oxide synthase have been ascribed to the cocoa flavonoids . Objective : To investigate the effects of flavonoid-rich dark chocolate on endothelial function , measures of oxidative stress , blood lipids , and blood pressure in healthy adult subjects . Design : The study was a r and omized , double-blind , placebo-controlled design conducted over a 2 week period in 21 healthy adult subjects . Subjects were r and omly assigned to daily intake of high-flavonoid ( 213 mg procyanidins , 46 mg epicatechin ) or low-flavonoid dark chocolate bars ( 46 g , 1.6 oz ) . Results : High-flavonoid chocolate consumption improved endothelium-dependent flow-mediated dilation ( FMD ) of the brachial artery ( mean change = 1.3 ± 0.7 % ) as compared to low-flavonoid chocolate consumption ( mean change = −0.96 ± 0.5 % ) ( p = 0.024 ) . No significant differences were noted in the resistance to LDL oxidation , total antioxidant capacity , 8-isoprostanes , blood pressure , lipid parameters , body weight or body mass index ( BMI ) between the two groups . Plasma epicatechin concentrations were markedly increased at 2 weeks in the high-flavonoid group ( 204.4 ± 18.5 nmol/L , p ≤ 0.001 ) but not in the low-flavonoid group ( 17.5 ± 9 nmol/L , p = 0.99 ) . Conclusion : Flavonoid-rich dark chocolate  improves endothelial function and is associated with an increase in plasma epicatechin concentrations in healthy adults . No changes in oxidative stress measures , lipid profiles , blood pressure , body weight or BMI were seen Cocoa flavanols ( CF ) influence physiological processes in ways that suggest their consumption may improve aspects of neural function , and previous studies have found positive influences of CF on cognitive performance . In this preliminary study we investigated whether visual , as well as cognitive , function is influenced by an acute dose of CF in young adults . We employed a r and omized , single-blinded , order counterbalanced , crossover design in which 30 healthy adults consumed both dark chocolate containing 720 mg CF and a matched quantity of white chocolate , with a one week interval between testing sessions . Visual contrast sensitivity was assessed by reading numbers that became progressively more similar in luminance to their background . Motion sensitivity was assessed firstly by measuring the threshold proportion of coherently moving signal dots that could be detected against a background of r and om motion , and secondly by determining the minimum time required to detect motion direction in a display containing a high proportion of coherent motion . Cognitive performance was assessed using a visual spatial working memory for location task and a choice reaction time task design ed to engage processes of sustained attention and inhibition . Relative to the control condition , CF improved visual contrast sensitivity and reduced the time required to detect motion direction , but had no statistically reliable effect on the minimum proportion of coherent motion that could be detected . In terms of cognitive performance , CF improved spatial memory and performance on some aspects of the choice reaction time task . As well as extending the range of cognitive tasks that are known to be influenced by CF consumption , this is the first report of acute effects of CF on the efficiency of visual function . These acute effects can be explained by increased cerebral blood flow caused by CF , although in the case of contrast sensitivity there may be an additional contribution from CF induced retinal blood flow changes CONTEXT Regular intake of cocoa-containing foods is linked to lower cardiovascular mortality in observational studies . Short-term interventions of at most 2 weeks indicate that high doses of cocoa can improve endothelial function and reduce blood pressure ( BP ) due to the action of the cocoa polyphenols , but the clinical effect of low habitual cocoa intake on BP and the underlying BP-lowering mechanisms are unclear . OBJECTIVE To determine effects of low doses of polyphenol-rich dark chocolate on BP . DESIGN , SETTING , AND PARTICIPANTS R and 
    Output:
    
It is unclear whether the effects of chocolate on mood are due to the orosensory characteristics of chocolate or to the pharmacological actions of chocolate constituents .
Further exploration of the effect of chocolate on cognitive facilitation is recommended , along with substantiation of functional brain changes associated with the components of cocoa