黄烷醇是一种天然抗氧化剂，在可可、黑巧克力中含量较高。黄烷醇会使黑巧克力和可可吃上去发苦，因此巧克力制造商曾花费数年时间想方设法去掉这种苦味。
2016年9月28日，美国营养学会（ASN）官方期刊《营养杂志》在线发表布朗大学、埃默里大学牛津学院、哈佛大学医学院、布莱根女子医院、哈佛大学陈曾熙公共卫生学院、沃伦·阿尔珀特医学院、罗得岛医院的研究报告，发现黄烷醇有益于心血管健康。
该研究通过系统回顾筛选出19项随机对照研究（共1131位参与者）进行荟萃分析，分析重点是与食用可可豆含量可忽略不计的产品相比，食用富含黄烷醇的可可产品是否与心脏代谢健康特定循环生物标志物改善有相关性。
结果发现，每天摄入黄烷醇200～600mg的人，血糖、胰岛素、胰岛素抵抗指标显著下降，高密度脂蛋白胆固醇增加。每天摄入黄烷醇＞600mg的人，仅见某些胰岛素抵抗指标和甘油三酯有所下降，但是高密度脂蛋白胆固醇却无显著增加。每天摄入黄烷醇＜200mg的人，仅见高密度脂蛋白胆固醇显著增加。
结果表明，摄入适量黄烷醇可能影响心脏代谢生物标志物，减少血脂异常（甘油三酯升高）、胰岛素抵抗和全身炎症，这些都是心脏代谢疾病的主要亚临床危险因素。该机理为未来设计针对大型的糖尿病和心血管疾病预防研究提供了指导。
不过，所有研究存在一些限制，影响范围都很小且持续时间短，而且在这些研究中，并非所有随访生物标志物都显著改善，并且无一研究直接检测黄烷醇摄入是否导致心脏病发作或2型糖尿病减少。
J Nutr. 2016 Sep 28. [Epub ahead of print]
Cocoa Flavanol Intake and Biomarkers for Cardiometabolic Health: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
Lin X, Zhang I, Li A, Manson JE, Sesso HD, Wang L, Liu S.
Brown University, Providence, RI; Oxford College of Emory University, Oxford, GA; Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Harvard T.H. Chan School of Public Health, Boston, MA; Warren Alpert Medical School and Rhode Island Hospital, Providence, RI.
BACKGROUND: Cocoa flavanols may improve cardiometabolic health. Evidence from small short-term randomized clinical trials (RCTs) remains inconsistent, and large long-term RCTs testing the efficacy of cocoa flavanols are still lacking.
OBJECTIVE: We performed a systematic review and meta-analysis of RCTs to quantify the effect of cocoa flavanol intake on cardiometabolic biomarkers.
METHODS: We searched PubMed, Web of Science, and the Cochrane Library for RCTs that evaluated the effects of cocoa flavanols on biomarkers relevant to vascular disease pathways among adults. Data were extracted following a standardized protocol. We used DerSimonian and Laird random-effect models to compute the weighted mean differences (WMDs) and 95% CIs. We also examined potential modification by intervention duration, design, age, sex, comorbidities, and the form and amount of cocoa flavanol intake.
RESULTS: We included 19 RCTs that comprised 1131 participants, and the number of studies for a specific biomarker varied. The amount of cocoa flavanols ranged from 166 to 2110 mg/d, and intervention duration ranged from 2 to 52 wk. Cocoa flavanol intake significantly improved insulin sensitivity and lipid profile. The WMDs between treatment and placebo were -0.10 mmol/L (95% CI: -0.16, -0.04 mmol/L) for total triglycerides, 0.06 mmol/L (95% CI: 0.02, 0.09 mmol/L) for HDL cholesterol, -2.33 μIU/mL (95% CI: -3.47, -1.19 μIU/mL) for fasting insulin, -0.93 (95% CI: -1.31, -0.55) for the homeostatic model assessment of insulin resistance, 0.03 (95% CI: 0.01, 0.05) for the quantitative insulin sensitivity check index, 2.54 (95% CI: 0.63, 4.44) for the insulin sensitivity index, -0.83 mg/dL (95% CI: -0.88, -0.77 mg/dL) for C-reactive protein, and 85.6 ng/mL (95% CI: 16.0, 155 ng/mL) for vascular cell adhesion molecule 1. No significant associations were found for other biomarkers. None of the modifiers seemed to qualitatively modify the effects of cocoa flavanol intake.
CONCLUSIONS: Our study suggests that cocoa flavanol intake has favorable effects on select cardiometabolic biomarkers among adults. These findings support the need for large long-term RCTs to assess whether cocoa flavanol intake reduces the risk of diabetes and cardiovascular events.
KEYWORDS: biomarkers; cardiometabolic health; cocoa flavanols; meta-analysis; randomized controlled trials
PMID: 27683874
PII: jn237644
DOI: 10.3945/jn.116.237644
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