摘錄自
Olive oil consumption and non-alcoholic fatty liver disease.
作者：Assy N, Nassar F, Nasser G, Grosovski M
Liver Unit, Ziv Medical Centre, Safed, Israel. assy.n@ziv.health.gov.il
橄欖油向來是地中海飲食的主要用油。其所富含的單元不飽和脂肪酸可以防止體內腹部脂肪堆積，降低胰島素阻抗性實驗對象體內因食用富含碳水化合物食物之後的脂肪連結蛋白質（Adiponectin，具有向下調節和肥胖，還有改善胰島素敏感性的能力）。實驗研究指出，橄欖油在治療代謝症候群有改善血脂的直接效用。未精煉（unrefined）或初榨橄欖油（virgin olive oil）具有有效抗氧化作用的生物活性物質（見圖一）。 橄欖油辣素，是僅存在於初榨橄欖油中的物質，是一種天然的抗炎化合物，其效力和成分極類似布洛芬（ibuprofen，是一種丙酸類之非類固醇類的抗發炎藥物）。單元不飽和脂肪酸和橄欖油透過橄欖油辣素可以修改肝臟 TG含量的實際機制並不明確。食用油中的油酸卻是與在總人口中有著較低的胰島素抗性有關。飲食富含橄欖油的確有助於身體脂肪的再分配和修改的脂肪細胞的脂解效率。此外，的N - 9脂肪酸（ω-9 fatty acid，如：油酸Oleic Acid便是其中的一種）可以調節週邊相關的胰島素敏感性的基因表現，增加內皮細胞血管反應，增加在脂肪組織和肌肉上的解藕聯蛋白核糖核酸成分，體現在肝臟中葡萄糖輸送第二型（glucose transporter-2，GLUT2 是葡萄糖轉運子，在胰臟β細胞它可調節葡萄糖的進入，一般認為它也是β細胞的葡萄糖感受器，GLUT2 失調會造成血糖調控混亂，GLUT2也會在肝臟中表現，是調空葡萄糖進出肝細胞的重要轉運子之一，可使肝臟發揮其緩衝進食後升高的血糖濃度）成分的增加。油酸降低在第二型糖尿病老鼠（Zucker fatty rats）體內參與肝臟糖異生（即將葡萄糖釋出到血液中）、脂肪生成與SREBP（Sterol response element-binding protein，為一指令物質，以控制肝臟內將糖變為脂肪的基因）的基因的體現。橄欖油的附加影響超出與橄欖多酚相關的單元不飽和脂肪酸的成分。存在於橄欖油中的多酚，諸如橄欖苦苷（oleuropin）、水合酪氨酸（hydroxytyrosol），酪醇（tyrosol）及咖啡酸（caffeic），皆具有重要的抗氧化和抗發炎的作用。在大鼠的白血球中，這些多酚分子已被證明能夠抑制白血球三烯素B4（leukotriene B4，是體內強烈的發炎物質）在五脂氧合酶（5-lipoxygenase，白三烯素B4為活化5-脂氧合酶代謝途徑而產生）的作用下再演進（成炎性物質），同時多酚分子亦能減少產生氧活性物質。此外，含有豐富的橄欖油飲食，與高碳水化合物飲食或高亞油酸飲食相較之下，更具有改善血管內皮功能。最後，不論單獨食用橄欖油或藉由地中海飲食去攝取，都能使腫瘤壞死因子（ TNF –α，為一種細胞素，通常被認為在發炎及其他一些免疫反映中扮演關鍵性角色的蛋白質之一）和血管細胞粘附分子-1（VCAM-1或CD106，vascular cell adhesion molecule-1，是人類基因和人類的蛋白質所共有的名稱，在免疫系統上扮演非常重要的角色） 血清水平[68] 呈現顯著的反向關聯，還能透過增加胰高血糖素樣肽1（GLP – 1，Glucagon-like peptide-1，是腸胃道荷爾蒙 incretin(腸泌素)中的一種。 主要在我們進食後，從腸胃道分泌出來，去加強胰島素的分泌，達到降低血糖的功能。），的分泌改善血糖耐受性。此外，相較於含有亞油酸的飲食，富含油酸的地中海式飲食，可藉由降低乳糜微粒（chylomicron，乳糜微粒有促進三酸甘油酯合成的作用,）殘留粒子的數量，減少動脈粥樣硬化的風險。橄欖油功效的主要機制是減少 NF –κB（nuclear factor kappa-light-chain-enhancer of activated B cells，是一種複合性蛋白質以控制DNA的複製，是一項與多種生理病理病變相關的誘發性因子，它的活化會使癌細胞持續進入細胞週期，而達到癌細胞增值不受藥品抑制的目的）活化，降低低密度脂蛋白的氧化以及改善胰島素抗性。
圖一:未精煉（unrefined）或初榨橄欖油（Extra Virgin / Virgin olive oil）
中具有有效抗氧化作用的生物活性物質及對脂肪肝的機制作用如下
Mechanisms of action of olive oil on fatty liver
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2670406/table/T2/
|
Machanism機制 |
Component involved 內含成分 |
|
Anti-inflammatory and immunomodulatory effects 抗炎和免疫調節作用 |
Oleic acid油酸 Phenolic compounds 酚類化合物 |
|
l Anti-oxidants抗氧化劑： l Decrease lipid peroxidation 降低脂肪過氧化 l Decrease oxidative DNAdamage 減少氧化DNA損傷 |
Oleic acid 油酸 Phenolic compounds酚類化合物: hydroxytyrosol水合酪氨酸, oleuropein橄欖苦苷, caffeic acid咖啡酸, o-coumaric acid鄰香豆酸, vanillic acid香草酸, 3,4-dihydroxyphenylethanol (3,4-DHPEA) 3.4二羥基本乙醇. |
|
Modulation of transduction pathways: 轉導路徑的調節 |
Oleic acid 油酸
|
|
Decreases arachidonic acid 降低花生四烯酸 |
Phenolic compounds酚類化合物: protocatechuic acid兒茶酸 |
|
Inhibits lipooxygenase 抑制脂氧化 |
Hydroxytyrosol 水合酪氨酸 |
|
Inhibits HMG-CoA reductase 抑制還原酶還原 |
Squalene 角鯊烯 |
|
Decreases RAS activation 降低原致癌基因的活性 |
Squalene角鯊烯
|
|
Regulation of gene expression in liver regeneration: 在肝臟再生中管理基因表現 |
Oleic acid油酸 Minor compounds次要化合物 |
|
(Oleic acid inhibits δ6-desaturase which decreases PGE2 and inhibits liver regeneration) 油酸抑制δ6 脫氫酶從而減少PGE2以及抑制肝臟再生 |
|
|
Change in membrane fluidity and membrane peroxidation (estrogen modulator, regulates G protein) 改變細胞膜的流體性質及過氧化 （雌激素調節，調節G蛋白） |
Oleic acid 油酸 Lignans（植物激素）木酚素 |
同篇報導其他續文 -
上述原文請詳下方或連結http://www.ncbi.nlm.nih.gov/pubmed/19370776
作者：Assy N, Nassar F, Nasser G, Grosovski M
Liver Unit, Ziv Medical Centre, Safed, Israel. assy.n@ziv.health.gov.il
Olive oil has traditionally been the principal oil of the Mediterranean diet. The MUFA diet prevents central body fat accumulation and decreases postprandial adiponectin expression induced by a carbohydrate-rich diet in insulin-resistant subjects[50,54]. Mechanistic studies show a direct beneficial role for olive oil in improving plasma lipids in the treatment of metabolic syndrome[44]. Unrefined or virgin olive oil has bioactive compounds with beneficial antioxidants action (Table 2)[48]. Oleocanthal, a component found in extra virgin olive oil, is a natural anti-inflammatory compound that has a potency and profile strikingly similar to that of ibuprofen[55]. The exact mechanism through which MUFAs and olive oil could modify hepatic TG content is not clear. Oleic acid from cooking oil was associated with lower insulin resistance in the general population[56]. An olive oil-enriched diet contributes to redistribution of body fat and modifies the lipolytic efficiency of fat cells[57]. Furthermore, n-9 fatty acids may regulate gene expression related to peripheral insulin sensitivity[58], increased endothelial vasoreactivity[59], up-regulation of uncoupling protein mRNA in adipose tissue and muscle[60], and expression of upregulates glucose transporter-2 in the liver[61]. Oleic acid decreases the expression of genes involved in hepatic gluconeogenesis and lipogenesis and SREBP in Zucker fatty rats[62]. Additional effects of olive oil beyond its MUFA composition relate to its polyphenols. Polyphenols present in olive oil, such as oleuropin, hydroxytyrosol, tyrosol and caffeic acid, have an important antioxidant and anti-inflammatory effect[63,64]. In rat leukocytes, these molecules have been shown to inhibit leukotriene B4 generation at the 5-lipoxygenase level and to reduce the generation of reactive oxygen species[65]. Moreover, a diet rich in olive oil improves endothelial function compared with a high carbohydrate diet or a high linoleic acid diet[66,67]. Finally, the consumption of olive oil as a single item or within a Mediterranean diet showed a significant inverse association with TNF-α and vascular cell adhesion molecule-1 serum levels[68], and improved glycemic tolerance through increased secretion of GLP-1[69]. Moreover, an oleic acid-rich Mediterranean type diet may reduce the risk of atherosclerosis by decreasing the number of chylomicron remnant particles as compared to a linoleic acid-enriched diet[70]. The principal mechanisms of action of olive oil are a decrease in NF-κB activation, a decrease in LDL oxidation and an improvement in insulin resistance (Figure (Figure11
留言列表
