Mullen William, Borges Gina, Donovan Jennifer L, Edwards Christine A, Serafini Mauro, Lean Michael E J, Crozier Alan
Division of Ecology and Evolutionary Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow, United Kingdom.
Am J Clin Nutr. 2009 Jun;89(6):1784-91. doi: 10.3945/ajcn.2008.27339. Epub 2009 Apr 29.
Cocoa drinks containing flavan-3-ols are associated with many health benefits, and conflicting evidence exists as to whether milk adversely affects the bioavailability of flavan-3-ols.
The objective was to determine the effect of milk on the bioavailability of cocoa flavan-3-ol metabolites.
Nine human volunteers followed a low-flavonoid diet for 2 d before drinking 250 mL of a cocoa beverage, made with water or milk, that contained 45 micromol (-)-epicatechin and (-)-catechin. Plasma and urine samples were collected for 24 h, and flavan-3-ol metabolites were analyzed by HPLC with photodiode array and mass spectrometric detection.
Milk affected neither gastric emptying nor the transit time through the small intestine. Two flavan-3-ol metabolites were detected in plasma and 4 in urine. Milk had only minor effects on the plasma pharmacokinetics of an (epi)catechin-O-sulfate and had no effect on an O-methyl-(epi)catechin-O-sulfate. However, milk significantly lowered the excretion of 4 urinary flavan-3-ol metabolites from 18.3% to 10.5% of the ingested dose (P = 0.016). Studies that showed protective effects of cocoa and those that showed no effect of milk on bioavailability used products that have a much higher flavan-3-ol content than does the commercial cocoa used in the present study.
Most studies of the protective effects of cocoa have used drinks with a very high flavan-3-ol content. Whether similar protective effects are associated with the consumption of many commercial chocolate and cocoa products containing substantially lower amounts of flavan-3-ols, especially when absorption at lower doses is obstructed by milk, remains to be determined.
含有黄烷 - 3 - 醇的可可饮品具有多种健康益处，关于牛奶是否会对黄烷 - 3 - 醇的生物利用度产生不利影响，存在相互矛盾的证据。
确定牛奶对可可黄烷 - 3 - 醇代谢产物生物利用度的影响。
9名人类志愿者在饮用250毫升用水或牛奶制成的可可饮料前，遵循低黄酮类饮食2天，该可可饮料含有45微摩尔（-）-表儿茶素和（-）-儿茶素。收集24小时的血浆和尿液样本，通过配备光电二极管阵列和质谱检测的高效液相色谱法分析黄烷 - 3 - 醇代谢产物。
牛奶既不影响胃排空，也不影响通过小肠的转运时间。在血浆中检测到2种黄烷 - 3 - 醇代谢产物，在尿液中检测到4种。牛奶对（表）儿茶素 - O - 硫酸盐的血浆药代动力学仅有轻微影响，对O - 甲基 - （表）儿茶素 - O - 硫酸盐没有影响。然而，牛奶显著降低了4种尿黄烷 - 3 - 醇代谢产物的排泄量，从摄入剂量的18.3%降至10.5%（P = 0.016）。显示可可具有保护作用以及显示牛奶对生物利用度无影响的研究，所使用产品的黄烷 - 3 - 醇含量远高于本研究中使用的商业可可。
大多数关于可可保护作用的研究使用的是黄烷 - 3 - 醇含量非常高的饮品。对于许多含有大量较低黄烷 - 3 - 醇的商业巧克力和可可产品的消费，尤其是当较低剂量的吸收受到牛奶阻碍时，是否具有类似的保护作用仍有待确定。
