Department of Food Science, University of Napoli Federico II, Portici, Italy.
Hepatology. 2010 Nov;52(5):1652-61. doi: 10.1002/hep.23902.
Epidemiological data associate coffee consumption with a lower prevalence of chronic liver disease and a reduced risk of elevated liver enzyme levels (γ glutamyl transpeptidase and alanine aminotransferase), advanced liver disease and its complications, and hepatocellular carcinoma. Knowledge of the mechanisms underlying these effects and the coffee components responsible for these properties is still lacking. In this study, 1.5 mL/day of decaffeinated coffee or its polyphenols or melanoidins (corresponding to approximately 2 cups of filtered coffee or 6 cups of espresso coffee for a 70-kg person) were added for 8 weeks to the drinking water of rats who were being fed a high-fat, high-calorie solid diet (HFD) for the previous 4 weeks. At week 12, HFD + water rats showed a clinical picture typical of advanced nonalcoholic steatohepatitis compared with control rats (normal diet + water). In comparison, HFD + coffee rats showed: (1) reduced hepatic fat and collagen, as well as reduced serum alanine aminotransferase and triglycerides; (2) a two-fold reduced/oxidized glutathione ratio in both serum and liver; (3) reduced serum malondialdehyde (lipid peroxidation) and increased ferric reducing antioxidant power (reducing activity); (4) reduced expression of tumor necrosis factor α (TNF-α), tissue transglutaminase, and transforming growth factor β and increased expression of adiponectin receptor and peroxisome proliferator-activated receptor α in liver tissue; and (5) reduced hepatic concentrations of proinflammatory TNF-α and interferon-γ and increased anti-inflammatory interleukin-4 and interleukin-10.
Our data demonstrate that coffee consumption protects the liver from damage caused by a high-fat diet. This effect was mediated by a reduction in hepatic fat accumulation (through increased fatty acid β-oxidation); systemic and liver oxidative stress (through the glutathione system); liver inflammation (through modulation of genes); and expression and concentrations of proteins and cytokines related to inflammation.
流行病学数据表明，喝咖啡与慢性肝病的患病率较低以及肝酶水平（γ-谷氨酰转肽酶和丙氨酸氨基转移酶）升高、晚期肝病及其并发症和肝细胞癌的风险降低有关。对于这些作用的机制以及导致这些特性的咖啡成分的了解仍然缺乏。在这项研究中，给之前 4 周内喂食高脂肪高热量固体饮食（HFD）的大鼠饮用水中添加 1.5 毫升/天的脱咖啡因咖啡或其多酚或黑素（相当于大约 2 杯过滤咖啡或 6 杯浓咖啡）8 周。在第 12 周，与对照大鼠（正常饮食+水）相比，HFD+水大鼠表现出非酒精性脂肪性肝炎晚期的典型临床症状。相比之下，HFD+咖啡大鼠表现出：（1）肝脂肪和胶原减少，血清丙氨酸氨基转移酶和甘油三酯减少；（2）血清和肝脏中还原型/氧化型谷胱甘肽比例降低两倍；（3）血清丙二醛（脂质过氧化）减少，铁还原抗氧化能力（还原活性）增加；（4）肝组织中肿瘤坏死因子α（TNF-α）、组织转谷氨酰胺酶和转化生长因子β表达减少，脂联素受体和过氧化物酶体增殖物激活受体α表达增加；（5）肝内促炎 TNF-α和干扰素-γ浓度降低，抗炎白细胞介素-4 和白细胞介素-10 浓度增加。
我们的数据表明，咖啡的摄入可以保护肝脏免受高脂肪饮食引起的损害。这种作用是通过减少肝脂肪堆积（通过增加脂肪酸β氧化）；全身和肝脏氧化应激（通过谷胱甘肽系统）；肝脏炎症（通过调节基因）；以及与炎症相关的蛋白质和细胞因子的表达和浓度来介导的。
