脂肪悖论
几乎所有的一切我们以为我们知道脂肪是错误的。
The "really bad fats," according to Barry Sears of区域fame, are saturated fats, trans fats, and arachidonic acid. He说多不饱和脂肪被称为花生四烯酸acid "may be the most dangerous fat known when consumed in excess."
每个人似乎都同意反式脂肪对我们来说真的很糟糕。但新的研究表明，我们吃的饱和脂肪和花生酸实际上是一件好事。
但这取决于。具体取决于我们是否遵循低碳水化合物或低脂肪饮食。
大多数卫生当局，包括美国糖尿病协会，仍然建议低脂饮食。这是Ancel Keys的遗产，一位医生对我们自己的善恶都太有说服力。他说服了美国医疗机构，脂肪是坏的，当这些专家们分析“七个国家的研究”时，碳水化合物很好。该研究似乎展现了心血管疾病与饱和脂肪酸的摄入之间的强烈关联。
It didn't. One of the great strengths of the new book,良好的卡路里，卡路里不好通过Gary Taubes，他是如何彻底暴露与心脏问题相关的甜味证据。皇帝，钥匙，象征性地没有衣服。
但是，当我们遵循低碳水化合物饮食时 - 意味着我们相应地增加我们吃多少脂肪 - 矛盾的事情发生。“你实际上可以吃更多饱和的脂肪，并在康涅狄格大学的助理学副教授杰夫S.Volek，博士杰夫S. Volek，博士表示，杰夫S.Volek，博士表示，杰夫S.Volek，博士说。
Volek博士是即将到来的研究的主要研究人员，“低脂肪和低碳水化合物饮食对循环脂肪酸组成和炎症标记的比较”脂质。期刊认为结果是如此重要的是，它以电子方式发布到印刷品和抽象是免费的在线的。Volek博士友好地向我发了一份整篇文章的副本，并在随访电话采访中回复了我的问题。
大多数人在膳食脂肪和血液中的脂肪之间发现这种反比关系违反直觉。在我开始研究脂肪代谢之前，我当然做过。
“这清楚地表明了你是你吃的想法的局限性，”Volek博士说。“新陈代谢发挥着重要作用。你是你的身体与你吃的东西的作用。”
Dr. Volek and his associates studied 40 overweight men and women for 12 weeks. They compared the results of the two groups on a very low-carb diet (35 grams of net carbs and 100 grams of fat, including 36 saturated grams) with a low-fat diet (191 grams of net carbs and 24 grams of fat, including 12 saturated grams). Both groups ate about 1500 calories per day.
尽管饮食中饱和脂肪的饱和脂肪较大，但血液中的饱和脂肪结果在低脂肪组中较高。这是由于称为碳水化合物诱导的脂肪生成的过程，我只是写道关于在“吃胖,变薄。”
"That's exactly right," Dr. Volek told me. "The main connection is with insulin. You can't ignore the carbohydrate-insulin axis. It's basic metabolism. You are taught in your elementary biochemistry that insulin is an anabolic hormone and it stimulates anabolic factors. So it promotes lipogenesis through a variety of transcription factors and at the same time inhibits lipid oxidation too, the lipase. No one argues that."
But that's as far as people have gone with it. Until now.
"Where people don't make the connection is that diet can actually impact that hormone, and that affects some of these outcomes that we are looking at," Dr. Volek continued. "It is really showing carbohydrate as a control element of metabolism and its effects on insulin."
They found that the very low-carb diet had a greater anti-inflammatory effect. It significantly reduced a couple of markers, particularly palmitoleic acid (16:1n-7), which is a well accepted surrogate for lipogenesis. That and the increased fat activation are the mechanisms, Dr. Volek says.
It must be hard for the establishment to swallow the saturated fat story. But it is probably throwing up on the new arachadonic acid research.
瓦尔克LED博士的新研究的甘蓝醛酸导致令人惊讶的是他们了解到饱和脂肪的知识。人们在非常低的碳水化合物中表现出基本上普遍认为为炎症造成的科希糖酸的大幅增加。但同时许多炎症标志物显着下降。
How is this possible?
"There has been this negative view of arachadonic acid, primarily because people have focused on its products rather than the intact fatty acid itself," Dr. Volek told me. "It is indeed the source of a lot of proinflammatory ecosanoids that promote inflammation and thrombosis and so forth, but that is only if it is acted upon by the oxygenators or if it comes in contact with molecular oxygen."
On a low-carb diet the difference is that we have less oxidative stress. So the arachadonic acid doesn't degrade. Its proportion in the membranes actually increases. In fact, the higher the arachadonic acid went up the less the inflammation, Dr. Volek told me.
"That is a totally new concept," he says. "There are a lot of misunderstandings and over-generalizations about arachadonic acid. We actually need to view arachadonic acid as a positive thing. It contributes to fluidity in membranes."
I couldn't resist asking Dr. Volek a personal question. "Do you follow a low-carb diet yourself?" I asked.
"I do," he replied. "I am happy to say that I am not a hypocrite."
他说他遵循这种饮食约20年，因为他感觉更好。他的饮食是10％至15％的碳水化合物，每天可能约50克。它比最近的研究中的低碳水化合物饮食有点多克，因为他没有体重问题。
Volek博士多年来一直在写一篇关于低碳水化合物饮食的措施，试图让这个词。对同行评审的文献中的MEDLINES搜索显示，他已经撰写或共同撰写的146篇牧业论文，其中许多人在低碳水化合物饮食中。
I asked him what comes next in his research. He says that he will study qualitative factors.
I told Dr. Volek that as I switched to a higher fat diet I am finding that the fats that I really like are cream cheeses and stuff like that, which are pure fat. I wonder whether it matters what the source of the fat is?
“这是一个非常好的问题，”他回答道。“我们现在正在进行试验，我们正在询问这个问题。这尚未在任何研究中正式解决，并且很难猜测会发生什么。当然在正常的碳水化合物摄入量下，你可以让你能够做出这种情况脂肪的类型，但是当你滴定碳水化合物时相当低，胰岛素很低，可能并不是那么重要。所以给我们大约6个月，我们将对这个问题有一些答案。“
我也想知道先进的糖化终端产品（AGEs). Are they as important a consideration on a low-carb diet as they clearly are on the standard high carb diet?
Dr. Volek says that A1C, which does go down when people follow a low-carb diet, is the only AGE marker that low-carb trials have measured. "But it is something that definitely needs to be pursued and documented."
I will, of course, pursue Dr. Volek and his further research and report his further findings here. Be prepared for even more paradoxes in this important and fascinating story of fat metabolism.
