Kyle Janet A M, Morrice Philip C, McNeill Geraldine, Duthie Garry G
Rowett Research Institute, Aberdeen AB21 9SB, Scotland, U.K.
J Agric Food Chem. 2007 Jun 13;55(12):4889-94. doi: 10.1021/jf070351y. Epub 2007 May 10.
Epidemiological studies assessing the health benefits of drinking black tea are equivocal. Such disparity may reflect an inability of semiquantitative assessment to consider how infusion time and addition of milk affect the bioavailability of potentially beneficial antioxidant polyphenols. Six brands of tea demonstrated similar increases in antioxidant capacity and total phenolic and catechin contents with increasing infusion time. These results were unaffected by the addition of milk. Consumption of black tea (400 mL) was associated with significant increases in plasma antioxidant capacity (10%) and concentrations of total phenols (20%), catechins (32%), and the flavonols quercetin (39%) and kaempferol (45%) (all p < 0.01) within 80 min. This was unaffected by adding milk. Infusion time may therefore be a more important determinant in the absorption of polyphenols from black tea. Observational studies assessing the health benefits of tea consumption require recording of brewing methods as well as frequency of consumption.
评估饮用红茶对健康益处的流行病学研究结果并不明确。这种差异可能反映出半定量评估无法考虑浸泡时间和添加牛奶对潜在有益抗氧化多酚生物利用度的影响。六个品牌的茶叶显示，随着浸泡时间的增加，抗氧化能力、总酚含量和儿茶素含量都有类似的增加。这些结果不受添加牛奶的影响。饮用红茶（400毫升）会使血浆抗氧化能力显著提高（10%），总酚（20%）、儿茶素（32%）以及黄酮醇槲皮素（39%）和山奈酚（45%）的浓度显著增加（所有p<0.01），且在80分钟内不受添加牛奶的影响。因此，浸泡时间可能是红茶中多酚吸收的一个更重要的决定因素。评估饮茶对健康益处的观察性研究需要记录冲泡方法以及饮茶频率。
