“癌症”抗氧化劑可以預防?

什麼是自由基?

自由基是高活性化學物質,有可能傷害細胞。它們是在原子或分子,獲得或失去電子時產生的。

自由基是人體自然形成的,並在許多正常細胞過程中發揮重要作用。然而,在高濃度下,自由基可能對身體有害並損害細胞的所有主要成分,包括DNA,蛋白質和細胞膜。

“癌症”抗氧化劑可以預防?


自由基引起的細胞損傷,特別是對DNA的損傷,也可以在癌症和其他健康狀況的發展中發揮作用。

暴露於電離輻射和其他環境毒素可導致體內異常高濃度的自由基。當電離輻射撞擊細胞中的原子或分子時,電子可能會丟失,從而形成自由基。異常高水平的自由基的產生是電離輻射殺死細胞的機制

此外,一些環境毒素,如香菸煙霧,某些金屬,可能含有大量的自由基或刺激人體細胞產生更多的自由基。

含有元素氧的自由基是活組織中產生的最常見的自由基類型。對於他們的另一名稱是“ 活性氧物質 ”

什麼是抗氧化劑?

抗氧化劑是與自由基相互作用並中和自由基的化學物質,從而防止它們造成損害。抗氧化劑也被稱為“自由基清除劑”。

身體會產生一些用來中和自由基的抗氧化劑。這些抗氧化劑被稱為內源性抗氧化劑,然而,身體依賴外部(外源)來源,主要是飲食,以獲得其所需的其他抗氧化劑。這些外源性抗氧化劑通常被稱為膳食抗氧化劑。

“癌症”抗氧化劑可以預防?


水果,蔬菜和穀物是膳食抗氧化劑的豐富來源。膳食抗氧化劑包括β-胡蘿蔔素,番茄紅素和維生素A,C和E(α-生育酚)。

抗氧化補充劑幫助預防癌症?

在實驗室和動物研究中,已經證明存在增加外源性抗氧化劑可以預防與癌症發展相關的自由基損傷類型。但是在人體體內如何呢?

許多觀察性研究,包括病例對照研究和隊列研究已經進行,以調查飲食抗氧化劑補充劑的使用是否與降低人類癌症風險相關。總體而言,這些研究得出了不同的結果。由於觀察性研究無法充分控制可能影響研究結果的偏倚,因此必須謹慎對待任何個體觀察性研究的結果。

迄今為止,已在全世界範圍內進行了用於預防癌症的膳食抗氧化劑補充劑的隨機對照試驗。

“癌症”抗氧化劑可以預防?


總體而言,這9項隨機對照臨床試驗未提供膳食抗氧化劑補充劑對原發性癌症預防有益的證據。

此外,對美國預防服務工作組(USPSTF)進行的有關使用維生素和礦物質補充劑預防慢性病(包括癌症)的現有證據的系統評價同樣沒有發現預防癌症的明確證據。

患癌症的人該服用抗氧化劑?

一些隨機對照試驗,已經研究了在癌症治療期間服用抗氧化劑補充劑是否會改變特定療法的有效性或降低其毒性。雖然這些試驗的結果好壞各半,但有些人發現在癌症治療期間服用抗氧化劑的人效果更差,特別是如果他們是吸菸者。


“癌症”抗氧化劑可以預防?


在一些臨床前研究中,已發現抗氧化劑可促進荷瘤小鼠的腫瘤生長和轉移,並提高其能力 流通腫瘤細胞發生轉移。在瞭解更多關於抗氧化劑補充劑對癌症患者的影響之前,應謹慎使用這些補充劑。癌症患者應告知醫生他們使用任何膳食補充劑。

其實人體有很強大的自動調節系統,不是說你吃了更多的抗氧化劑,身體自由基就清除的更多,同時我們也沒必要清除所有自由基。如果服用可以針對性短期進行干預,但是請找專業的營養醫師給您評估。

-參考文獻-

文章提供者:營養師-李宗沅

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