Fielding Barbara A
Department of Nutritional Sciences, University of Surrey, Guildford, Surrey, UK.
Curr Opin Clin Nutr Metab Care. 2017 Sep;20(5):360-365. doi: 10.1097/MCO.0000000000000404.
In 2004, the 'Ω-3 index' was described as the sum of eicosapentaenoic acid (EPA, 20 : 5 n-3) and docosahexaenoic acid (DHA, 22 : 6 n-3) in red blood cells (RBCs) as an index of coronary heart disease mortality. This review outlines new evidence to support the Ω-3 index as a tool to inform disease prognosis.
Recent studies have reported differential metabolism of EPA and DHA. High-dose supplementation with EPA and DHA led to increased levels of RBC DHA that were associated with decreased liver fat. EPA and DHA in RBCs were associated with reduced mortality in a prospective study of patients with cardiac disease; the strongest association was with EPA. A diet containing 9.5-g α-linolenic acid lead to an increase in EPA but not DHA status in middle-aged women.
Dietary intake or supplementation studies with n-3 fatty acids should include measurement of n-3 status in a standardized way. The Ω-3 index, reflecting EPA and DHA status throughout the body, is convenient and may be appropriate in some cases, but as EPA and DHA assimilate differently in membranes, and have different potency, measurement of individual fatty acid composition in RBCs may be more informative.
2004年，“Ω-3指数”被描述为红细胞（RBC）中二十碳五烯酸（EPA，20:5 n-3）和二十二碳六烯酸（DHA，22:6 n-3）的总和，作为冠心病死亡率的一个指标。本综述概述了新的证据，以支持将Ω-3指数作为一种用于判断疾病预后的工具。
近期研究报告了EPA和DHA的代谢差异。高剂量补充EPA和DHA导致RBC中DHA水平升高，这与肝脏脂肪减少有关。在一项对心脏病患者的前瞻性研究中，RBC中的EPA和DHA与死亡率降低相关；最强的关联是与EPA。一项含有9.5克α-亚麻酸的饮食导致中年女性的EPA水平升高，但DHA状态未改变。
n-3脂肪酸的膳食摄入或补充研究应以标准化方式包括对n-3状态的测量。反映全身EPA和DHA状态的Ω-3指数很方便，在某些情况下可能适用，但由于EPA和DHA在细胞膜中的同化方式不同且效力不同，测量RBC中单个脂肪酸组成可能更具信息量。
