Does the keto diet live up to its promise?
生酮饮食是否实现了它的承诺？
By Vicky Stein, UC San Francisco
As Silicon Valley trendsetters, famous actors, and online health sites tout the low-carbohydrate, high-fat ketogenic, or “keto,” diet, scientists are working to study it — from how it impacts inflammation in the brain to its effects on weight and heart health, as well as any other potential health risks.
正如硅谷的潮流引领者、著名演员和在线健康网站所吹嘘的低碳水化合物、高脂肪酮(Keto)饮食一样，科学家们正致力于研究它-从它如何影响大脑炎症，到它对体重和心脏健康的影响，以及其他潜在的健康风险。
Among the researchers studying the diet’s effectiveness and safety are Ethan Weiss, M.D., and Raymond Swanson, M.D., two UC San Francisco physician-scientists who have studied different aspects of the ketogenic diet.
在研究这种饮食的有效性和安全性的研究人员中，两位来自加州大学旧金山分校的内科医生伊桑·韦斯（Ethan Weiss）博士和雷蒙德·斯旺森（Raymond Swanson）博士研究了生酮饮食的不同方面。
The ketogenic diet tries to bring carbohydrates down to less than 5 percent of a person’s daily caloric intake — which means eliminating most grains, fruit, starchy vegetables, legumes and sweets. Instead, it replaces those calories with fat. That fat is turned into ketone bodies, which are an alternative energy source: besides glucose derived from carbohydrates, ketones from fat are the only fuel the brain can use.
生酮饮食试图将碳水化合物减少到一个人每日卡路里摄入量的5%以下-这意味着消除大部分谷物、水果、淀粉类蔬菜、豆类和糖果。相反，它用脂肪代替了这些卡路里。脂肪转化为酮体，这是一种替代能源：除了碳水化合物产生的葡萄糖外，脂肪中的酮是大脑唯一可以使用的燃料。
Weiss and Swanson helped break down the keto diet.
韦斯博士和斯旺森博士帮助打破了生酮饮食。
“If we’re going to make a claim, let’s stick to the things we know,” said Weiss.
韦斯博士说：“如果我们要提出索赔，那就要坚持我们所知道的事情。”
What we know
我们所知的：
Swanson, a professor of neurology who has researched the impacts of ketogenic diets on inflammation in the brain, got curious about the ketogenic diet when trying to treat the inflammation that persists for days after a person suffers a stroke. When he tried inducing a ketogenic state in mice with stroke injuries, he said, “I was overwhelmed by the effect.” Blocking glucose metabolism worked to suppress inflammatory genes, which in turn helped stroke healing.
斯旺森是神经学教授，他研究了生酮饮食对大脑炎症的影响。当试图治疗由中风引起的持续炎症时，他对生酮饮食产生了好奇。当他试图将患有中风损伤的小鼠诱发成酮症状态时，他说：“我被这种效果吓得不知所措。”阻断葡萄糖代谢能够抑制炎症基因，有助于中风愈合。
The anti-inflammatory effect of ketosis on stroke recovery is likely the same effect that helps children with certain kinds of seizures, said Swanson, who is a member of the UCSF Weill Institute for Neurosciences. Ketogenic diets have been used as treatment for some forms of epilepsy for almost a century.
“酮症对中风康复过程中的抗炎作用很可能与治疗某类癫痫儿童的作用相同，”斯旺森说，他是UCSF 韦尔神经科学研究所（Weill Institute for Neurosciences）的成员，生酮饮食已经被用作治疗某类癫痫近一个世纪了。
Weiss, an associate professor at the Cardiovascular Research Institute who studies the effects of diet on weight and heart health, has been an adviser for Virta Health Corp., a company that is treating type 2 diabetes by controlling patients’ blood glucose levels through a ketogenic diet.
韦斯是心血管研究所的副教授，研究饮食对体重和心脏健康的影响。他一直是维塔健康公司（Virta Health Corp.）的顾问。维塔健康公司是一家通过生酮饮食控制患者血糖水平来治疗2型糖尿病的公司。
“It’s incredibly powerful,” said Weiss of the keto diet. “Cutting back on carbohydrates, there are so many metabolic benefits. The body processes the remaining carbohydrates more efficiently, and so it requires much less insulin.”
“这是难以置信的强大，”维斯评价生酮饮食。“减少碳水化合物，在代谢方面有很多好处。因为身体能更有效地处理剩余的碳水化合物，所以它所需的胰岛素要少得多。“
Frederick Hecht, M.D., research director of the UCSF Osher Center for Integrative Medicine, also is performing more trials aimed at people with type 2 diabetes. In the controlled trials, a ketogenic state has shown promise in improving human glucose control and decreasing the need for diabetes medications.
医学博士弗雷德里克·赫克特，UCSF 奥舍综合医学中心的研究主任，也针对2型糖尿病患者进行更多相关试验。在对照试验中，生酮状态在改善人类葡萄糖控制和减少糖尿病药物需求方面显示出了希望。
What we don’t know
我们所不知的：
One big hurdle to the knowledge about the keto diet’s impact on humans is that many of the benefits — helping reduce inflammation in the brain, improving outcomes after brain injury and extending lifespan — have only been found in studies in mice.
要了解生酮饮食对人类的影响，还存在一个很大的障碍：关于帮助减少大脑炎症，改善脑损伤后的结果以及延长寿命的好处，只是在对老鼠的研究中发现的。
Far fewer clinical studies have been done in humans outside of seizure prevention since ketosis is a difficult state to maintain; avoiding carbs, including fruit, bread, legumes, and the occasional office birthday cake isn’t feasible for many people in the long run.
由于酮症是一种难以维持的状态，除了预防癫痫之外，对人类进行的临床研究要少得多；从长远来看，避免碳水化合物，包括水果、面包、豆类和偶尔的办公室生日蛋糕对许多人来说是不可行的。
Without peer-reviewed clinical trials, many of the benefits remain anecdotal. For instance, Weiss himself has been on a low-carb high-fat (though not strictly ketogenic) diet for more than six months, and claims he does feel much better. But he’s clear about what he knows and what he doesn’t. He’s lost weight and his borderline pre-diabetes is gone.
如果没有同行评审的临床试验，许多好处仍然只是传闻。例如，韦斯自己已经吃了六个多月的低碳水化合物高脂肪饮食(虽然不是严格意义上的生酮)，并声称他确实感觉好多了。但他很清楚他所知道的和不知道的。当他体重减轻了的同时，他的糖尿病前期症状也消失了。
“I think I feel great,” he said. But that might be because he’s eating less processed food, sleeping better, or enjoying compliments on his new physique.
“我感觉很棒，”他说。但这可能是因为他吃的加工食品变少且睡得更好了，或者是对他新体型的欣赏。
As to the most exotic claims from health and diet gurus — such as keto diets resulting in euphoria, cognitive boosts, and improvements in anything from kidney function to cancer treatment — “We just don’t have the data on that yet,” said Weiss.
至于健康饮食大师们最具异国情调的说法-比如生酮饮食让人心情愉悦，认知能力提升，以及帮助改善肾功能及癌症治疗等方面-“我们只是还没有这方面的数据，”韦斯说。
The researchers agree that the diet itself isn’t inherently dangerous. But, cautions Weiss, “If you have any medical condition, if you take any medicine at all – there are lots of things that change how medicines work in our bodies, and nutrition is definitely one of them. If you’re making a real change in your nutrition, you really should talk to your doctor.”
研究人员一致认为，饮食本身并没有本质上的危险。但是，韦斯警告说，“如果你患有任何疾病，如果你在吃某些药物，有很多事情会改变药物在我们的身体中的运作方式，食物绝对是其中之一。如果你正在改变你的饮食，你真的应该和你的医生谈谈。”
