【长寿指南】左旋肉碱（L-carnitine）：功效与作用、安全性和服用方法

左旋肉碱（L-Carnitine）是一种由赖氨酸和蛋氨酸在体内合成的化合物[1,2]。它天然存在于我们的体内，尤其是在肌肉组织中，也可以从食物中获取，红肉（如牛肉、猪肉） 是其主要膳食来源[3,4]，可以作为补充品服用。左旋肉碱可以乙酰化生成乙酰-左旋肉碱（ALCAR），其与左旋肉碱相似，但能更有效地穿越血脑屏障[5]。

它在人体内的核心生理功能是作为“运输车”，将长链脂肪酸运送到线粒体内部进行氧化，从而为身体产生能量[1,6]。因此，它对于维持细胞，特别是能量需求高的心肌和骨骼肌细胞的正常功能至关重要。

2020 年，《Aging》期刊发表的一项研究显示，给线虫喂养 50 mM的左旋肉碱，可以将线虫的最大寿命延长 28% [7]。

根据长寿之家Changshou.com制定的《长寿成分评级标准（2025 版）》，左旋肉碱的延寿证据等级为 D。

点击查看长寿之家Changshou.com《延寿天梯榜》。

 抗炎：一项随机对照临床试验招募了 254 名 2 型糖尿病患者，发现每天 2 克左旋肉碱+ 10 毫克西丁曲明（药物）联合治疗，12 个月后与单独用药组相比，左旋肉碱组更快地改善了空腹血糖、餐后血糖、以及炎症因子 TGF-α 和 C 反应蛋白水平[8]。

一项随机对照平行研究纳入了 46 名活动性类风湿性关节炎患者，他们被平均随机分配到组。一组仅接受传统 DMARDs 治疗（甲氨蝶呤、来氟胺和羟氯喹），另一组接受 DMARDs 辅助 500 毫克左旋肉碱，持续 12 周，结果显示左旋肉碱与 DMARDs 联合使用，可以通过减轻系统性炎症来改善类风湿关节炎的临床结局[18]。

改善运动表现、缓解疲劳：有多项临床试验显示，每天 2 克的左旋肉碱可以提高运动时的氧气摄入量。降低血浆乳酸水平，从而改善了肌肉能量代谢，提升了运动表现[9-12]。而左旋肉碱补充剂还有助于减少运动引起的肌肉酸痛和肌肉损伤，促进运动恢复[13]。

改善男性生殖能力：一项纳入 50 项治疗持续时间超过 12 周随机对照试验的荟萃分析结果显示，1–3 克/天的左旋肉碱或左旋乙酰肉碱可以提升男性精子的活动性[14]。

另有一项随机对照双盲临床试验招募了 40 名勃起功能障碍患者，被随机分配口服丙酰左旋肉碱（2 克/天）加西地那非（药物，每周两次 50 毫克）、或单独使用西地那非，治疗 24 周后，结果发现前者比后者更加有效[15]。

改善女性生殖能力：同样，左旋肉碱可以改善多囊卵巢综合征（PCOS）女性的排卵和妊娠率。一项总样本量为 835 参与者的荟萃分析结果显示，肉碱能改善排卵率、临床妊娠以及 PCOS 女性的胰岛素抵抗和BMI（体质指数）[16]。

改善代谢：大量的临床研究表明，每天补充 1-3 克的左旋肉碱/乙酰左旋肉碱可以改善代谢，包括但不限于代谢综合征的症状，如改善血压，血糖，血脂（包括甘油三酯、总胆固醇、低密度脂蛋白胆固醇）等[19-24]。

减肥：一些荟萃分析还发现，补充左旋肉碱、乙酰左旋肉碱或丙酰左旋肉碱对减重有小范围（约1公斤）的有益效果[32-34]。

降低偏头痛发作频率：一项随机对照试验招募了 133 名偏头痛患者，随机分配到三个干预组：氧化镁（500 毫克/天）、左旋肉碱（500 毫克/天）和氧化镁+左旋肉碱（各 500 毫克/天）和一个对照组，补充 12 周，结果发现，每个干预组的偏头痛发作频率显著降低[17]。但仍需大规模试验验证这一发现。

左旋肉碱可能引发的副作用，包括消化问题、体味、癫痫发作、潜在心脏风险和过敏反应[25-27]。

左旋肉碱补充剂的一个独特副作用是“鱼腥味”体味，这是由于汗液和尿液中的三甲胺的积累和排出引起的[25]。

左旋肉碱的作用机制尚不完全清楚。在肌肉等组织中，左旋肉碱被发现有助于将长链脂肪酸“输送”到线粒体中以产生能量[1,6]。进一步证据表明，它可能通过增强抗氧化能力、保护细胞膜免受氧化应激、减少炎症以及提高一氧化氮水平来发挥潜在益处[28-31]。

目前在国内，左旋肉碱已被批准用于保健食品，作为健身、减肥的营养补充剂使用。

孕妇、哺乳期女性：目前尚没有足够的证据支持来了解左旋肉碱在怀孕或哺乳期间大量使用左旋肉碱是否可以安全地用作药物。为了安全起见，只需从食物中获取即可。

儿童：尚缺乏安全性数据，同上。

肝肾疾病患者：肝肾疾病患者代谢功能受限，服用左旋肉碱可能加重肝肾负担。

癫痫患者：有研究表明左旋肉碱有可能诱发癫痫发作。

过敏反应：对肉碱类成分过敏的人，应尽量避免服用。

通常左旋肉碱可以从饮食中充分获取，身体也通常能够产生足够的左旋肉碱。

目前临床实验中用的左旋肉碱的标准剂量为每天 500-2000 毫克，是相对安全的剂量。需注意，如果选择服用乙酰左旋肉碱，则等效剂量高达约 2700 毫克/天，丙酰左旋肉碱的等效剂量高达约 2900 毫克/天。

首次服用建议从低剂量开始，逐步观察身体反应，待身体适应在逐步增加剂量。

参考资料：

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