鱼油的两面性:癌症与营养剂
生物通 · 2016/04/11
这篇文章引发了轩然大波。世界各地的新闻媒体都报道癌症治疗期间服用膳食补充剂的危险性。


荷兰癌症研究所的医学肿瘤学教授Emile Voest将毕生的精力都花在了肿瘤微环境的研究上,这是癌症的细胞背景支持,涉及了从肿瘤结构支撑,到肿瘤对抗免疫系统,再到其对癌症治疗药物的抗性等多方面机制。

然而Voest表示,二十世纪头十年的中期,他与其他研究人员发现了两个令人费解的多不饱和脂肪酸:16:4(n-3) 和 KHT,这两种脂肪酸似乎会诱导肿瘤小鼠产生化疗耐药性,这令他们感到有些惊讶。

“我没想到它们具有这种作用,”Voest说,“我们也不清楚这些脂肪酸是什么,如何发挥作用的。”

研究人员发现将人类骨髓间充质干细胞 (涉及耐药性的多能基质细胞)注入到肿瘤小鼠之后,这些正在服用顺铂(cisplatin)的小鼠就会开始分泌这些脂肪酸,顺铂是一种用于治疗多种类型癌症的铂类药物。铂诱导脂肪酸 (platinum-induced fatty acids,PIFAs) 对肿瘤的生长没有影响,但会中和癌细胞中顺铂的细胞毒性,从而指出了接受铂类药物的患者在化疗过程中出现耐药性的一种可能机制。

但更令人意外的发现还在后头——Voest等人顺着PIFAs 的线索往下挖,结果偶然发现了海洋研究中经常提到的16:4(n-3)的新作用,“我们突然想到这种脂肪酸存在于鱼类中,”Voest说,“所以我们检查了鱼油。”果然,在鱼油产品和海藻提取物中都存在毫摩尔的16:4(n-3),而这些正是癌症患者进行化疗时被推荐的营养剂。

大约五分之一的美国癌症患者在摄入Ω-3脂肪酸,通常都是通过鱼油。Voest等人调查了2011年10月的400名接受治疗的癌症患者。在反馈的118名患者中,35%的患者在服用营养补充剂,11%的患者在服用Ω-3脂肪酸补充剂。同时他们也要求未患癌症的志愿者摄入10ml或50ml三种鱼油补充剂。摄入10ml补充剂的人血中16:4(n-3)含量4小时达峰值;约8小时后降至正常。摄入50ml的人血中脂肪酸含量持续升高。

Voest指出即使是少量的两种脂肪酸也会削减肿瘤小鼠的化疗效果,这些脂肪酸可能最终会加速化疗后癌症细胞的自我修复,因此化疗患者应该避免在治疗前后摄入鱼油——鲭鱼和鲱鱼。

这篇文章引发了轩然大波。世界各地的新闻媒体都报道癌症治疗期间服用膳食补充剂的危险性。

不过不少科学家则认为这不足以支持在癌症预防过程减少鱼油使用的观点,来自斯坦福大学的临床营养师Erika Connor表示,“大多数研究表明鱼油具有积极作用,能防止肌肉萎缩,并且在某些情况下辅助化疗药物作用。”

英属哥伦比亚大学的Rachel Murphy指出,“人类与动物模型的脂肪酸代谢过程存在极大差异……很多时候,研究结果不能转换。”

对此,Voest表示,“我们提供的只是数据,具体情况还要大家自己决定。我只知道如果我的病人或我的朋友亲戚正在进行化疗,我肯定会劝他们避免食用鱼油。”

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