Please wait a minute...
浙江大学学报（农业与生命科学版）
浙江大学学报(农业与生命科学版)  2013, Vol. 39 Issue (2): 119-121    DOI: 10.3785/j.issn.1008-9209.2012.11.061
评论     
Omega-3指数的概念和应用
1.甘肃省第二人民医院药剂科，兰州730000;2.浙江大学食品科学与营养系，杭州 310058
Concept of omega-3 index and its application
1. Department of Pharmacy, Gansu 2nd People’s Hospital, Lanzhou 730000, China; 2. Department of Food Science and Nutrition, Zhejiang University, Hangzhou 310058, China
 全文: PDF(833 KB)   HTML ( ) 
摘要： Omega-3（又称ω--3或n-3）指数的概念是2004年由Harris和von Schacky［1］提出的，它是通过测红细胞膜二十碳五烯酸（eicosapentaenoic acid, EPA；C20:5n-3）和二十二碳六烯酸（docosahexaenoic acid, DHA；C22:6n-3）的含量（占红细胞膜总脂肪酸的比例），作为生物标记物来反映习惯膳食n-3 多不饱和脂肪酸（polyunsaturated fatty acid, PUFA）的摄入.n-3指数作为心源性猝死的风险因子已被广泛使用［2］，与冠状动脉疾病的风险因子——低密度脂蛋白胆固醇相似，其检测试剂盒已经于2009年问世（http://www.genesmart.com/pages/omega3indextest/80.php）.n-3指数与冠心病病死率呈显著负相关，当n-3指数大于或等于8%时，对心脏具有强大的保护作用，冠心病病死率将降低一半以上，而当n-3指数小于或等于4%时对心脏的保护作用甚微［1］. 普遍认为动脉性血栓在从稳定转化为急性缺血性心、脑病变时，临床上表现为不稳定的心绞痛、急性血栓性梗死以及猝死，在心血管系统疾病中其动脉性血栓起着主角作用.而血小板聚集又是血栓形成的最初阶段［3］.血小板聚集由血栓烷A2（thromboxane A2, TXA2）启动，其为一强大的血小板聚集因子和血管收缩剂，由血小板细胞膜中的花生四烯酸（arachidonic acid, AA）产生［3］.增加膳食n3脂肪酸的摄入，特别是EPA和DHA的摄入，会增加组织细胞膜的EPA和DHA浓度，从血小板细胞膜磷脂中释放出来的EPA与AA竞争性地结合环氧合酶(cyclooxygenase, COX)，从而产生血栓烷的一种替代形式TXA3, 但其在血小板聚集及血管收缩方面相对无活性或活性不高，因此这使得TXA2的生成减少，从而降低了形成血栓的趋势，同时产生“3”系列前列腺素、前列腺环素和“5”系列白三烯（leukotriene, LT）以及脂氧素（lipoxin），这些物质具有抗感染、抗血小板聚集、平滑肌松弛等活性，对心血管系统均有保护作用［4］.富含EPA 和DHA的油在一定程度上可二次预防心肌梗塞.此外，EPA 和DHA均可防止致命性的心律失常，增加心率变化，降低血清中甘油三酯（triacylglycerol, TAG）水平，降低收缩压和舒张压，调节心肌细胞中的离子流量，抑制炎性因子的产生和活性［5］，降低血浆同型半胱氨酸的浓度等［6］. EPA 和DHA可调节很多基因的表达，例如EPA 和DHA可下调蛋白聚糖分解酶、致炎因子（白介素1α和TNFα）、COX2脂肪酸合成酶、乙酰辅酶A羧化酶、S14蛋白质、硬脂酰辅酶A去饱和酶以及胱硫醚γ裂解酶的活性.同时，n-3 PUFA可上调脂蛋白脂酶脂肪酸结合蛋白、乙酰辅酶A合成酶、肉碱棕榈酰转移酶1、乙酰辅酶A脱氢酶、乙酰辅酶A氧化酶、细胞色素P450 4A2 以及过氧化物酶增殖体激活受体α等酶的活性［5］以及蛋氨酸腺苷转移酶［7］. 在大多数生物细胞膜中，磷脂的主要组成成分是脂肪酸，长链n-3和n-6 PUFA在维持细胞膜结构和功能上具有重要作用.DHA在人和其他哺乳动物的视网膜和大脑中的含量很高，对膜的次序（流动性），膜上酶的活性、离子通道以及信息的转导有着重要作用.DHA是维持视觉和大脑功能不可缺少的物质，对细胞膜的流动性具有重要功能.通过其对膜的流动性作用，进而影响细胞膜受体（如视紫质）的功能，调节膜结合酶（如Na/K依赖性腺苷三磷酸酶）的活性，并能通过对肌醇磷酸盐、甘油二脂和蛋白激酶C的作用，影响信号的传递.DHA可直接影响神经递质的生物合成、信号的传递、血清素的吸收、β-肾上腺素能受体和血清素激活受体的结合作用以及一元胺氧化酶的活性［5］. n-3 PUFA是一类含3个以上双键、从甲基端算起第1个双键位于第3和第4个碳原子之间的一系列化合物，广泛分布于动物和植物组织中.食物中存在的n-3 PUFA主要是α亚麻酸（linolenic acid, ALA；C18:3n-3）、DHA、EPA和鲱油酸（docosapentaenoic acid, DPA；C22:5n-3）.ALA与亚油酸（linoleic acid, LA；C18:2n-6）是人体的必需脂肪酸，人体自身不能合成，也不能从其他脂肪酸转化而来，所以必需从食物中摄入［8］.ALA大量存在于植物油中，如紫苏油和墨西哥油中含60%~70%、亚麻子中含55%~60%、Canola中含10%、大豆油中含7%、胡桃油中含13%［9］.ALA是C20和C22长链n-3 PUFA的前体物质.DHA和EPA主要存在于鱼、鱼油以及其他海洋生物中，而DPA主要存在于鱼、肉以及肉制品中.杂食人群既可从饮食中摄取ALA，又可从鱼、蛋或动物性产品中直接得到长链n-3 PUFA.乳蛋素食人群（ovolactovegetarian）可从牛奶、乳制品和蛋类中获取有限量的长链n-3 PUFA.而对于严格的素食人群则必须完全依靠内源性合成，即通过ALA的去饱和与碳链延长反应合成长链n-3 PUFA（图1）［5］.因为一般植物不能将ALA转化为长链n-3 PUFA，故在严格的素食者的饮食中没有长链n-3 PUFA可直接利用.
Abstract: The concept of the “omega3 (n-3) index” is proposed by Harris and von Schacky［1］ in 2004, which is by measuring red cell membrane eicosapentaenoic acid (EPA; C20:5n-3) and docosahexaenoic acid (DHA; C22:6n-3) content (% of total fatty acids), as a biomarker to reflect the customary dietary n-3 polyunsaturated fatty acid (PUFA) intake. Omega3 index is a risk factor of sudden cardiac death［2］, which is similar with low density lipoprotein cholesterol, a risk factor for coronary artery disease. Omega3 index is significantly negatively correlated with coronary heart disease mortality, and it has a strong cardioprotective effect. Coronary heart disease mortality will be reduced by more than half when the n-3 index is greater than or equal to 8%, however, cardioprotective effect will be least when the n-3 index is less than or equal to 4%［1］. It is generally considered that arterial thrombosis was converted from stable acute ischemic heart and brain lesions. Among the clinical manifestations of unstable angina, the acute thrombotic infarction, sudden death and diseases of the cardiovascular system, the arterial thrombosis plays the protagonist role. The platelet aggregation is the initial stage of the thrombus formation［3］. EPA and DHA protective effect on the cardiovascular system is by the following mechanisms: The platelet aggregation is initiated by thromboxane A2 (TXA2), which is a powerful platelet aggregation factor and vasoconstrictor, and is generated by the platelet membrane from the arachidonic acid (AA)［3］. Increased dietary intake of n-3 PUFA, especially EPA and DHA, will increase the tissue membrane concentration of EPA and DHA. Released EPA from the platelet membrane phospholipids competitive binding of the cyclooxygenase (COX) with AA, thereby generating an alternative form of thromboxane A3 (TXA3), it is relatively nonplatelet aggregation and vasoconstriction activity, so it leads to a reduced formation of TXA2. Thereby results in the formation of thrombotic tendency. Meanwhile, it produces 3series prostaglandins and prostacyclin and 5series leukotriene (LT) and lipoxins (lipoxin)［4］, which have antiinflammatory, antiplatelet aggregation and smooth muscle relaxation activity. Marine oil is rich in EPA and DHA with a beneficial effect on the secondary prevention of myocardial infarction. In addition, EPA and DHA may prevent fatal arrhythmias, increase heart rate changes, reduce the level of serum triacylglycerol (TAG), lower systolic and diastolic blood pressure, regulate the flow of ions in myocardial cells, inhibit inflammatory cytokine production and activity［5］, and reduce plasma homocysteine concentration［6］. EPA and DHA may regulate the expression of many genes, for example, EPA and DHA can downregulate protein glycans decomposing enzyme (aggrecanases) proinflammatory cytokines (interleukin1α and TNFα), COX2 fatty acid synthase, acetyl coenzyme A carboxylase, methionine adenosyltransferase, S14 protein and stearyl coenzyme A desaturase, and they can upregulate the lipoprotein lipase fatty acidbinding protein, acetyl coenzyme A synthetase, carnitine palmitoyl transferase enzyme 1, acetyl coenzyme A dehydrogenase, acetyl coenzyme A oxidase, cytochrome P450 4A2, peroxisome proliferatoractivated receptor α［5］ and cystathionineglyase［7］. In most biological membranes, the major component of the phospholipid is fatty acid, in which the long chain n-3 and n-6 PUFAs have an important role in maintaining the structure of the cell membrane and function. In the retina and the brain of humans and other mammals, there is a high content of DHA, which plays an important role in order (fluidity) of the membrane, the activity of the membrane enzymes, ion channels, and the conduction of information. DHA is an indispensable substance of maintaining visual and brain functions because of its cell membrane fluidity. It has an important role in membrane fluidity, thereby affecting the function of the membrane receptor (such as rhodopsin), regulating the membranebound enzymes (such as Na/K  dependent adenosine triphosphatase) of the active, and pass on the inositol phosphate, diacylglycerol and protein kinase C, to affect the transmission of signals. The DHA may directly affect the biosynthesis of the neurotransmitter, the absorption of serotonin, the signal transmission, β-adrenergic receptors and serotonergic receptor binding as well as a monoamine oxidase activity［5］.
出版日期: 2013-03-20
通讯作者: 李铎（本刊编委），男，教授，从事食品营养学方面的研究。Tel：+86-571-88982024；E-mail：duoli@zju.edu.cn   
服务　　
把本文推荐给朋友
加入引用管理器
E-mail Alert
RSS
作者相关文章　　
金永新1
李铎2*

引用本文:

金永新1， 李铎2*. Omega-3指数的概念和应用 [J]. 浙江大学学报(农业与生命科学版), 2013, 39(2): 119-121.

JIN Yongxin1, LI Duo2*. Concept of omega-3 index and its application. Journal of Zhejiang University (Agriculture and Life Sciences), 2013, 39(2): 119-121.

链接本文:

http://www.zjujournals.com/agr/CN/10.3785/j.issn.1008-9209.2012.11.061    或    http://www.zjujournals.com/agr/CN/Y2013/V39/I2/119

No related articles found!