黑巧克力可改善心衰指标

洛杉矶——美国心脏协会(AHA)科学年会上报告的一项随机、双盲、交叉初步试验表明，慢性心衰患者每天食用一块黄酮醇含量非常高的特制黑巧克力，可带来血压和左心室后负荷下降的有益变化。

伦敦大学玛丽皇后学院的Roger Corder博士指出：“需要强调的是，这些患者已经接受了治疗指南推荐的最大耐受量药物的治疗。就医学干预来说，我们已基本别无他法。因此，我认为除继续寻找新的药物外，还应考虑一些有证据基础的新饮食，考察它们能否降低心衰患者的发病率和死亡率。”


Roger Corder博士

研究者认为，心衰患者的受益可能与黑巧克力引起内皮功能障碍减少有关。既往研究表明，每日食用≥750 mg可可黄酮醇可改善冠心病患者、健康人群或糖尿病患者内皮功能。

该研究纳入32例接受最大剂量药物治疗的稳定性心衰患者，他们均有缺血性心脏病史。受试者被随机分为2组，接受每日食用一块50g高黄酮醇或低黄酮醇巧克力的交叉试验，各4周。高黄酮醇巧克力为定制产品，每块含有1,094 mg黄酮醇，远远高出市售产品(平均含量为312 mg/50 g)，而低黄酮醇对照品仅含95 mg。研究终点为食用每种巧克力4周后舒张压和脑钠肽前体N末端(NT-proBNP)水平的变化。

结果显示，24例完成试验的患者平均基线NT-proBNP水平为200 pmol/L，食用4周高黄酮醇巧克力后平均下降39%。研究者指出，鉴于其他药物(包括血管经张素受体抑制剂)试验表明NT-proBNP水平下降30%可导致临床结局改善，而上述24例患者中有12例NT-proBNP下降≥30%，因此非常期待开展进一步的临床研究。受试者基线血压为126/71 mmHg，食用高黄酮醇巧克力后舒张压下降5 mmHg，收缩压无显著变化。研究者认为，收缩压维持不变而舒张压下降，意味着心脏输出量增加，这是最理想的结果。食用低黄酮醇巧克力未能引起血压或NT-proBNP变化。

不过高黄酮醇巧克力在试验中暴露出两方面的缺点：其一是口味，8例退出患者中有3例患者抱怨产品味道不能接受，即便是完成试验的患者也不喜欢这一味道。其二是体重增加，受试者基线体重为84.7kg，4周后增加约0.3kg。两种巧克力每50g中均含有约19 g的脂肪(包括12g的饱和脂肪)和260卡路里的热量。

研究者承认这种黑巧克力可能不太合适患者长期每天食用，但参与这项研究的食品科学家正对其口味进行改进，还可以将黄酮醇提取后添加到其他营养食品中。

该研究由瑞士巧克力巨头Barry Callebaut资助。Corder博士报告接受了该公司提供的研究经费。

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By: BRUCE JANCIN, Cardiology News Digital Network

LOS ANGELES – Chronic heart failure patients who ate a special superhigh-flavonol dark chocolate bar daily experienced favorable changes consistent with decreased vascular resistance and diminished left ventricular afterload in a randomized, double-blind, crossover pilot study.

"It should be emphasized that these patients were already on maximal tolerated guideline-indicated therapy. In terms of medical interventions, there weren’t many more things we could do. So I think that in addition to looking at new drugs, we need to look at evidence-based new diets to see if they can reduce morbidity and mortality in heart failure," Dr. Roger Corder said in presenting the chocolate study results at the annual scientific sessions of the American Heart Association.

The likely mechanism of benefit in heart failure patients involves a dark chocolate–induced reduction in endothelial dysfunction.

"Prior studies show consumption of cocoa flavonols in daily doses of 750 mg or more improve endothelial function in patients with coronary artery disease, in healthy subjects, and in diabetics," noted Dr. Corder of Queen Mary University of London.

The study involved 32 patients with stable heart failure on maximal medical therapy, all of whom had a history of ischemic heart disease. They were randomized to daily consumption of a 50-g bar of high-flavonol chocolate or a low-flavonol chocolate bar for 4 weeks, then crossed over to daily consumption of the other bar for another 4 weeks.

The test product contained 1,094 mg of flavonols per bar, while the low-flavonol comparator contained 95 mg. The high-flavonol chocolate bar was a custom-made product whose flavonol content far exceeds anything on the market. Dr. Corder and coinvestigators tested 50 brands of commercially available dark chocolate bars averaging 76% cocoa solids and determined their average flavonol content was 312 mg/50 g.

The study end points were change in diastolic blood pressure and N-terminal prohormone of brain natriuretic peptide (NT-proBNP) levels after 4 weeks of eating each type of chocolate bar.

Twenty-four patients completed the study. Mean NT-proBNP dropped by an average of 39% from a baseline of 200 pmol/L after 4 weeks of eating the high-flavonol chocolate.

"Given that other trials of medications, including angiotensin receptor blockers, have shown a 30% reduction in NT-proBNP is associated with improved clinical outcomes, this looks to us like something of interest to pursue further with additional clinical studies. It’s worth noting that 12 of the 24 patients had a drop in NT-proBNP of 30% or more," Dr. Corder said.

From a baseline blood pressure of 126/71 mm Hg, diastolic pressure fell by 5 mm Hg in conjunction with consumption of the high-flavonol bar. Systolic pressure did not change significantly. Maintenance of systolic blood pressure with a reduction in diastolic pressure implies an increase in cardiac output – "and that would really be the optimum thing to have happened," he continued.

The low-flavonol chocolate bar did not produce changes in blood pressure or NT-proBNP.

A couple of down sides with the experimental high-flavonol chocolate bar emerged during the study. One was taste. Three of the eight study dropouts quit because they found the product’s taste unacceptable, while the others left for reasons unrelated to the study.

"We had an issue with taste. Even the patients who finished the study didn’t like the taste. There may be other countries where dark chocolate is popular, but the East of London would rather have their sweet milk chocolate than dark chocolate," according to Dr. Corder.

Weight gain is another concern. Both chocolate bars contained about 19 g of fat, including 12 g of saturated fat, per 50-g serving, with about 260 calories. From a baseline body weight of 85.7 kg, participants gained roughly 0.3 kg over the course of 4 weeks.

"In terms of long-term therapy, it may not be suitable to take dark chocolate on a daily basis at this level," he said.

However, food scientists involved in the study are tweaking the recipe to improve the taste of the superhigh-flavonol bar. There is also the option of extracting the flavonols and placing them in some other nutraceutical food product.

The study was funded by Swiss chocolate giant Barry Callebaut. Dr. Corder reported receiving a significant research grant from the company.