Living Longer by Reducing Leucine Intake
減少亮氨酸攝入來長壽
原文網址：https://nutritionfacts.org/2015/06/16/living-longer-by-reducing-leucine-intake/
原文作者：Michael Greger M.D.
Many studies have shown that calorie restriction, without malnutrition, can increase lifespan and lower the risk of age-related diseases, such as cancer.
多項研究都表明，在沒有營養不良的情況下，限制熱量攝入，可以增壽，並降低癌症等年齡相關疾病的風險。
However, for many people, calorie restriction clearly has its drawbacks. In the classic Minnesota Starvation Study, many of the volunteers suffered a preoccupation with food, constant hunger, binge eating, and lots of emotional and psychological issues. Even researchers who study caloric restriction rarely practice it. There’s got to be a better way to suppress the aging engine enzyme, TOR.
不過，對於很多人來說，限制熱量攝入明顯有其缺點。在經典的「明尼蘇達飢餓研究」中，很多志願者變得對食物過分執著、動輒飢餓、暴飲暴食，還出現了很多情緒和心理上的問題。即使研究限制熱量攝入的研究者自己，也很少去親身體驗。其實，在限制熱量攝入之外，還有更好的方式來抑制推動人老化的酶——TOR（雷帕黴素靶蛋白）。
That’s why researchers were so excited about rapamycin, a drug that inhibits TOR, thinking it could be caloric restriction in a pill. But like any drug, it a long list of potentially serious side effects. There’s got to be a better way.
研究者對雷帕黴素——一種抑制TOR的藥物——如此興奮，其原因即在此。他們以為，吃這麼一片藥，就可以實現限制熱量攝入的效果。但是，跟其他任何藥物一樣，雷帕黴素有很多潛在的嚴重副作用——應該還有更好的方法。
The breakthrough came when scientists discovered that the benefits of dietary restriction may be coming not from restricting calories, but from restricting protein intake. If we look at the first comprehensive, comparative meta-analysis of dietary restriction, 「the proportion of protein intake was more important for life extension than the degree of caloric restriction.」 In fact, just 「reducing protein without any changes in calorie level have been shown to have similar effects as caloric restriction.」
突破性的一刻到來了：科學家發現，節制飲食的好處，可能不是來自限制熱量，而是來自限制蛋白質攝入。我們來看一看對節制飲食的首次綜合性比較型Meta分析。對於長壽來說，「相比限制熱量的程度，蛋白質攝入的比例更重要。」實際上，「熱量水平沒有任何變化的情況下」，僅僅「減少蛋白質」，就「已經顯示出跟限制熱量同樣的效果。」
That’s good news. Protein restriction is much less difficult to maintain than dietary restriction, and it may even be more powerful because it suppresses both TOR and IGF-1, the two pathways thought responsible for the dramatic longevity and health benefits of caloric restriction.
這是個好消息。相比節制飲食，限制蛋白質做起來輕鬆得多，而且，由於這樣做能同時抑制TOR和IGF-1（胰島素樣生長因子1）——限制熱量攝入有顯著的長壽和健康好處，公認就是通過這兩條途徑實現的。
Some proteins are worse than others. One amino acid in particular, leucine, appears to exert the greatest effect on TOR. In fact, just cutting down on leucine may be nearly as effective as cutting down on all protein. Where is leucine found? Predominantly animal foods: eggs, dairy, and meat (including chicken and fish). Plant foods, such as fruits, vegetables, grains, and beans, have much less.
某些蛋白質比其他蛋白質更糟糕。尤其是一種胺基酸，亮氨酸，看起來對TOR影響最大。事實上，僅僅削減亮氨酸的攝入，可能就差不多跟削減蛋白質總量一樣有效。亮氨酸見於何處？主要是動物食品：蛋、奶和肉（包括雞肉和魚肉）。植物食品，比如水果、蔬菜、穀物和豆類，含量少得多。
「In general, lower leucine levels are only reached by restriction of animal proteins.」 To reach the leucine intake provided by dairy or meat, we』d have to eat nine pounds of cabbage—about four big heads—or 100 apples. These calculations exemplify the extreme differences in leucine amounts provided by a conventional diet in comparison to a plant-based diet. The functional role of leucine in regulating TOR activity may help explain the extraordinary results reported in the Cornell-Oxford-China Study, 「since quasi-vegan diets of modest protein content tend to be relatively low in leucine.」
「總之，較低的亮氨酸水平，只能通過限制動物蛋白質攝入來實現。」要達到一餐奶和肉提供的亮氨酸攝入，我們必須吃9磅的捲心菜——大約4大顆——或100個蘋果。這種換算舉例說明了，相比植物性飲食，常規的一餐飯（譯者註：指普通的美式飲食）所提供的亮氨酸量有多大差別。亮氨酸在調節TOR活性上發揮的功能性作用，可有助於解釋康奈爾-牛津-中國研究中報告的非凡成果，「因為蛋白質含量有節制、類似純素的飲食，往往亮氨酸比較低。」
This may also help explain the longevity of populations like the Okinawa Japanese, who have about half our mortality rate. The traditional Okinawan diet is only about 10% protein, and practically no cholesterol, because they ate almost exclusively plants. Less than one percent of their diet was fish, meat, eggs, and dairy – the equivalent of one serving of meat a month and one egg every two months. Their longevity is surpassed only by vegetarian Adventists in California, who have perhaps the highest life expectancy of any formally studied population in history.
這也可有助於解釋，日本衝繩人——他們的死亡率只有我們的一半——等人群的長壽。傳統的衝繩飲食，蛋白質只佔大約10%，實際上沒有膽固醇，因為他們幾乎只吃植物（譯者註：請參看本公眾號往期文章：百歲老人怎麼吃？）。他們的飲食中，魚、肉、蛋和奶佔比不到1%——相當於一個月才吃一份肉，每兩個月才吃一個雞蛋。只有加州素食的基督復臨派教徒的壽命比他們長。這些教徒，可能是歷史上正式研究過的人群中預期壽命最長的。
歡迎掃描如下二維碼關注本公眾號，並把它介紹給熱愛人生，富有學習激情的親朋，鍛鍊英語閱讀能力，積累營養學知識。