前些日子看到一篇由Richard Alleyne撰寫的文章《A genuine‘elixiroflife’》，說實話，讀完以后我有些興奮，它預示我們：新型“長生不老藥”即將問世！從古至今人類一直都在追求長生不老，如今這個夢想似乎不再遙不可及了。英國《每日電訊報》本月5日也刊出同樣報道：科學家發現了一種能夠延年益壽的藥物，而且已經在小白鼠身上進行實驗，并獲得成功，人類首次證明了氨基酸混合物能夠延長壽命，支鏈氨基酸將全面改寫抗衰老學說，也將全面引爆抗衰老保健品及藥品市場。

原文如下：

A genuine ‘elixir of life’

      In laboratory experiments, middle-aged male healthy mice were given drinking water laced with three specific amino acids.

      The animals lived significantly longer than other mice fed a normal diet.

      Their lifespan range had a midpoint of 869 days compared with 774 days for untreated mice, a difference of 12 per cent.

      Longer survival was accompanied by biological changes which boosted the energy supply to cells and reduced oxidative damage caused by destructive molecules called free radicals.

      The treated mice had more stamina and improved muscle co-ordination.

      "This is the first demonstration that an amino acid mixture can increase survival in mice," said study leader Dr Enzo Nisoli, from the University of Milan in Italy.

      Last year scientists showed that the same amino acids, leucine, isoleucine and valine, could extend the lifespan of single-celled yeast.

      The new findings, reported in the journal Cell Metabolism, raise the possibility of amino acid supplements benefiting humans.

      The scientists pointed out that the mice studied were aged but otherwise healthy.

      They believe taking the amino acids might be especially helpful for the elderly or ill, particularly people with heart failure, chronic lung disease, or other conditions characterised by flagging energy levels.

      Dr Nisoli said a large patient trial was needed to provide evidence convincing enough for doctors. However, there was little financial incentive for companies to conduct such studies on dietary supplements.

      Leucine, isoleucine and valine, known as branched-chain amino acids (BCAAs), account for a fraction of the 20 amino acids from which proteins are made, but appear to have special anti-ageing properties.

      Mice given the three amino acids produced larger numbers of mitochondria - the rod-like "powerhouses" in cells that generate energy - in their heart and skeletal muscle.

      They also showed increased activity of SIRT1, a well-known longevity gene, and developed better defences against free radicals.

BCAA nutritional supplements are readily available in health food stores and online.

      Amino acid supplements were likely to be more effective than consuming proteins containing the same amino acids, according to the researchers.

      Unlike protein, they did not have to be digested, and could enter the bloodstream immediately.

      "They come with no energy cost," said Dr Nisoli.

      In their paper the scientists wrote: "We have provided evidence that an original BCAA mixture increases average life span in male mice.

      "This was likely the consequence of increased mitochondrial biogenesis and reduced oxidative stress in cardiac and skeletal muscles.

      Our study offers a rationale for deeply exploring the role of amino acids in prevention and

control of age-related disorders in humans."

這種神奇的藥物就是由亮氨酸、異亮氨酸和纈氨酸這3種氨基酸組成的混合物，學名“支鏈氨基酸”。

支鏈氨基酸（branchedchainaminoacid，BCAAs），是一種十分重要和有效的營養補劑，其側鏈具有分支結構的氨基酸。在蛋白質中常見的有蘇氨酸、纈氨酸和異亮氨酸等，它可以幫助生物體自然地、沒有任何副作用地增強肌肉或獲得更多能量。

對于我們長期研究保健品研究的人來說，支鏈氨基酸并不陌生，最初我們認為支鏈氨基酸對任何運動的人群來說都是最重要和最有效的營養補劑。這點非常重要，那就是如果你想要自然地、沒有任何副作用地來增加肌肉或獲得更多能量，那你就要考慮使用支鏈氨基酸了。支鏈氨基酸以兩種特殊方式促進合成代謝（肌肉增長）：

①     釋放胰島素；

②     釋放生長激素。

支鏈氨基酸中最重要的是亮氨酸，即酮異己酸（KIC）和HMB的前身。KIC和HMB可增加肌肉肉，減少脂肪，并為人體提供營養。乳清蛋白的BCAA含量較高。運動訓練后應補充4－5克。支鏈氨基酸可以通過血流進入大腦，降低大腦的5羥色胺的產生，而5羥色胺可使人產生疲倦感。通過減少5羥色胺的含量可減輕腦力疲勞。當你在想練就出更強壯、更有力的身體時，在細胞水平上刺激和給你的肌肉供能是必要的，支鏈氨基酸組成幾乎1/3肌肉蛋白。BCAAs能減緩肌肉疲勞，加速恢復，降低運動時其它氨基酸從肌肉中的丟失，并有助于機體吸收蛋白質。缺乏其中三者之一將導致肌肉丟失。不象其它氨基酸，BCAAs在肌肉中代謝，而不是在肝臟。支鏈氨基酸之間在吸收能力上具有相互競爭性，因此必須同時補充，以保證最大程度的吸收。訓練時肌肉中支鏈氨基酸的消耗也是很快的，運動前或運動中補充支鏈氨基酸可以提高運動能力和延緩疲勞。運動后或運動后隨餐服用支鏈氨基酸可以降低皮質醇（損害肌肉的罪魁禍首）和快速恢復肌肉中支鏈氨基酸的水平。支鏈氨基酸作為氮的載體，輔助合成肌肉合成所需的其它氨基酸，簡單說，它是一個簡單氨基酸合成復雜完整肌肉組織的過程。因此，支鏈氨基酸刺激胰島素的產生（胰島素的主要作用就是允許外周血糖被肌肉吸收并作為能量來源），胰島素的產生也促進肌肉對氨基酸的吸收。支鏈氨基酸既有合成作用，也有抗分解作用，因為它們可以顯著增加蛋白合成，促進相關激素的釋放，如生長激素（GH、IGF-1胰島素樣生長因子-1）和胰島素以及有助于維持一個合理的睪酮及皮質醇比例。

當然，這些都是我們以往對支鏈氨基酸的研究課題，現如今，支鏈氨基酸不僅僅是一種運動后的營養添加劑，它還將全面改寫抗衰老學說，也將全面引爆抗衰老保健品及藥品市場。這項研究的主要研究員是來自意大利米蘭大學的恩佐·尼索里教授，他還指出，如果在此基礎上發明氨基酸補劑，那么它在未來造福人類，對于老年人或病人有很大幫助，尤其是那些患有以細胞能級降低為特征的疾病的人，比如心力衰竭或慢性肺病患者等。

研究人員在實驗過程中，給被試小白鼠喝的水里加入了這3種氨基酸，結果發現它們的壽命平均達到了869天，而普通小白鼠最高則只能存活大約774天。也就是說，“支鏈氨基酸”使小白鼠的生命延長了12%。在延長壽命的同時，小白鼠的機體內還發生了一系列積極的生物反應，比如細胞得以攝取更多的能量、自由基減少等。（自由基是機體氧化反應中產生的有害化合物，具有強氧化性，可損害機體的組織和細胞，進而引起慢性疾病及衰老效應。）經過這些體內變化，小白鼠看起來充滿活力，而且肌肉協調能力有所提高。科學家已經發現這種氨基酸混合物在延長單細胞酵母壽命上的巨大作用。