Hirano-Ohmori Reiko, Takahashi Rie, Momiyama Yukihiko, Taniguchi Hiroaki, Yonemura Atsushi, Tamai Seiichi, Umegaki Keizo, Nakamura Haruo, Kondo Kazuo, Ohsuzu Fumitaka
First Department of Internal Medicine, National Defense Medical College, Tokorozawa, Saitama 359-8513, Japan.
J Am Coll Nutr. 2005 Oct;24(5):342-6. doi: 10.1080/07315724.2005.10719483.
Green tea was shown to inhibit LDL oxidation, platelet aggregation, and matrix metalloproteinases (MMPs) activities in vitro. We tried to elucidate whether or not green tea consumption may have these effects in vivo, which may be protective against atherosclerotic disease.
We measured serum malondialdehyde-modified LDL (MDA-LDL) concentrations and urine 8-epi-prostaglandin (PG) F(2alpha) in 22 healthy male nonsmokers. They drank 7 cups/day of water for 2 weeks and drank 7 cups/day of green tea for the next 2 weeks. Regarding platelet aggregation, plasma thromboxane B(2) (TXB(2)) and 6-keto-PGF(1alpha) concentrations and ex vivo platelet aggregation were evaluated. Plasma MMP-2 and -9 concentrations were also measured.
Of the 22 subjects, 20 had been in the habit of drinking green tea before the study. Plasma catechins concentrations significantly decreased at the end of the water period and then increased at the end of the green tea period. Although no change in plasma LDL-cholesterol concentrations (110 +/- 33 vs. 113 +/- 28 mg/dL, p = NS) was found, MDA-LDL concentrations (84 +/- 45 vs. 76 +/- 40 IU/L, p < 0.05) and the ratio of MDA-LDL/LDL-cholesterol (0.74 +/- 0.21 vs. 0.65 +/- 0.20, p < 0.02) significantly decreased at the end of the green tea period. However, no significant changes were observed in urine 8-epi-PGF(2alpha) concentrations, in platelet aggregation, nor in plasma TXB(2), 6-keto-PGF(1alpha) or MMP concentrations.
Daily consumption of green tea decreased serum MDA-LDL concentrations, but it had no significant effects on platelet aggregation, platelet TX production or plasma MMPs concentrations. Our results suggest that green tea consumption may inhibit LDL oxidation in vivo.
绿茶在体外已显示出可抑制低密度脂蛋白（LDL）氧化、血小板聚集及基质金属蛋白酶（MMPs）活性。我们试图阐明饮用绿茶在体内是否具有这些作用，而这些作用可能对动脉粥样硬化疾病具有保护作用。
我们检测了22名健康男性非吸烟者的血清丙二醛修饰的LDL（MDA-LDL）浓度及尿8-表前列腺素（PG）F(2α)。他们连续2周每天饮用7杯水，随后的2周每天饮用7杯绿茶。关于血小板聚集，评估了血浆血栓素B(2)（TXB(2)）和6-酮-PGF(1α)浓度以及体外血小板聚集情况。还检测了血浆MMP-2和-9浓度。
22名受试者中，20人在研究前有饮用绿茶的习惯。血浆儿茶素浓度在饮水期结束时显著降低，然后在绿茶期结束时升高。尽管未发现血浆LDL胆固醇浓度有变化（110±33 vs. 113±28 mg/dL，p = 无显著差异），但MDA-LDL浓度（84±45 vs. 76±40 IU/L，p < 0.05）以及MDA-LDL/LDL胆固醇比值（0.74±0.21 vs. 0.65±0.20，p < 0.02）在绿茶期结束时显著降低。然而，尿8-表-PGF(2α)浓度、血小板聚集、血浆TXB(2)、6-酮-PGF(1α)或MMP浓度均未观察到显著变化。
每日饮用绿茶可降低血清MDA-LDL浓度，但对血小板聚集、血小板TX生成或血浆MMP浓度无显著影响。我们的结果表明，饮用绿茶可能在体内抑制LDL氧化。
