Are eggs helpful to our health… or a cause of heart disease? BBC Future examines the evidence.
鸡蛋是对我们健康有好处...还是能导致心脏病？
BBC未来频道对证据进行了查看
By Jessica Brown/ September 17, 2019
剪辑：BM︱翻译：Ray︱校对：Sally
If there was such a thing as a perfect food, eggs would be a contender. They’re readily available, easy to cook, affordable and packed with protein.
要说有一种完美的食物的话，鸡蛋将是一个选择。它们很容易买到，易于烹调，价格实惠，而且富含蛋白质。“The egg is meant to be something that has all the right ingredients to grow an organism, so obviously it’s very nutrient dense,” says Christopher Blesso, associate professor of nutritional science at the University of Connecticut in the US.美国康涅狄格大学营养科学副教授克里斯托弗·布尔索说：“鸡蛋本来就是一种含有所有适合生长有机成分的东西，所以很明显它营养丰富。”But for decades, eating eggs has also been controversial due to their high cholesterol content – which some studies have linked to an increased risk of heart disease. One egg yolk contains around 185 milligrams of cholesterol, which is more than half of the 300mg daily amount of cholesterol that the US dietary guidelines recommended until recently. 但几十年来，由于鸡蛋的高胆固醇含量，食用鸡蛋也一直备受争议——一些研究表明，鸡蛋会增加患心脏病的风险。一个蛋黄含有大约185毫克的胆固醇，这已达到美国饮食指南一直建议的每日300毫克胆固醇的一半以上。Cholesterol is transported around our body by lipoprotein molecules in the blood. Every person has a different combination of various types of lipoproteins, and our individual make-up plays a role in determining our risk of developing heart disease.胆固醇是通过血液中的脂蛋白分子在我们的身体内部运动的。每个人都有不同类型的脂蛋白的组合，我们每个人的不同构成决定了我们患心脏病风险的大小。lipoprotein molecules：脂蛋白分子But researchers haven’t definitively linked consumption of cholesterol to an increased risk of cardiovascular disease. As a result, US dietary guidelines no longer have a cholesterol restriction; nor does the UK. Instead, emphasis is placed on limiting how much saturated fat we consume, which can increase the risk of developing cardiovascular disease. Foods containing trans fats, in particular, increase our LDL levels. Although some trans fats occur naturally in animal products, most are made artificially and are found in highest levels in margarines, snacks, and some deep-fried and baked foods, such as pastry, doughnuts and cake.但研究人员还没有明确地将胆固醇的摄入与心血管疾病风险的增加联系起来。因此，美国的饮食指南不再有胆固醇限制；英国也没有。相反，重点是限制我们摄入的饱和脂肪，这会增加患心血管疾病的风险。特别是含有反式脂肪的食物，会增加我们的低密度脂蛋白水平。虽然有些反式脂肪天然存在于动物产品中，但大多数是人工制造的，在人造黄油、零食和一些油炸和烘焙食品，如糕点、甜甜圈和蛋糕中，含量最高。Meanwhile, along with prawns, eggs are the only food high in cholesterol that are low in saturat同时，除了大虾，鸡蛋是唯一一种胆固醇含量高、饱和脂肪含量低的食物。“While the cholesterol in eggs is much higher than in meat and other animal products, saturated fat increases blood cholesterol. This has been demonstrated by lots of studies for many years,” says Maria Luz Fernandez, professor of nutritional sciences at the University of Connecticut in the US, whose latest research found no relationship between eating eggs and an increased risk of cardiovascular disease.美国康涅狄格大学营养科学教授玛丽亚·卢兹·费尔南德斯（maria luz fernandez）说：“虽然鸡蛋中的胆固醇远远高于肉类和其他动物产品，但只是饱和脂肪会增加血液中的胆固醇。多年来的许多研究都证明了这一点。”她的最新研究发现，吃鸡蛋与心血管疾病风险增加之间没有关联。“There are systems in place so that, for most people, dietary cholesterol isn’t a problem,” says Elizabeth Johnson, research associate professor of nutritional sciences at Tufts University in Boston, US.美国波士顿塔夫茨大学营养学研究副教授伊丽莎白·约翰逊说：“我们已有的系统对大多数人来说，饮食中的胆固醇不会成为问题。”In a 2015 review of 40 studies, Johnson and a team of researchers couldn’t find any conclusive evidence on the relationship between dietary cholesterol and heart disease.在2015年对40项研究的总结中，约翰逊和研究人员无法找到任何关于饮食胆固醇与心脏病之间关系的确凿证据。“Humans have good regulation when consuming dietary cholesterol, and will make less cholesterol themselves,” she says. And when it comes to eggs, cholesterol may pose even less of a health risk. Cholesterol is more harmful when oxidised in our arteries, but oxidisation doesn’t happen to the cholesterol in eggs, says Blesso.她说：“人类在食用食物中的胆固醇时有很好的管控，而且自己也会制造更少的胆固醇。” 而在鸡蛋方面，胆固醇对健康的危害可能更小。当胆固醇在我们的动脉中被氧化时，它的危害更大，但是鸡蛋中的胆固醇不会被氧化，布莱索说。Also, some cholesterol may actually be good for us. High-density lipoprotein (HDL) cholesterol travels to the liver, where it’s broken down and removed from the body. HDL is thought to have a protective effect against cardiovascular disease by preventing cholesterol from building up in the blood.另外，一些胆固醇对我们有好处。高密度脂蛋白（HDL）胆固醇进入肝脏，在那里被分解并从体内排出。高密度脂蛋白被认为通过防止胆固醇在血液中积聚而对心血管疾病有防护作用。What matters is the ratio of HDL to LDL in our bodies, as elevated HDL counteracts the effects of LDL.重要的是我们体内高密度脂蛋白与低密度脂蛋白的比例，因为高密度脂蛋白抵消了低密度脂蛋白的影响。Trials have found that lean and healthy people are more likely to see an increase in LDL after eating eggs. Those who are overweight, obese or diabetic will see a smaller increase in LDL and more HDL molecules, Blesso says. So, if you’re healthier to begin with, eggs potentially could have a more negative effect than if you’re overweight – but if you’re healthier, you’re also more likely to have good HDL levels, so an increase in LDL probably isn’t very harmful.试验发现，体瘦而健康的人在吃鸡蛋后更容易显现低密度脂蛋白的增加。布莱索说，那些超重、肥胖或糖尿病患者的低密度脂蛋白和高密度脂蛋白分子的增加幅度较小。因此，如果你一开始就非常健康，鸡蛋可能会对你产生更明显的负面影响——但如果你更健康，你也更可能有良好的高密度脂蛋白水平，所以低密度脂蛋白的增加应该不会造成更大的伤害。Research published earlier this year, though, challenged the recent consensus that eggs pose no harm to our health. Researchers looked at data from 30,000 adults followed for an average of 17 years and found that each additional half an egg per day was significantly linked to a higher risk of heart disease and death. (They controlled for the subjects’ diet patterns, overall health and physical activity to try to isolate the effects of eggs.)不过，今年早些时候发表的一项研究结果挑战了最近达成的共识，即鸡蛋不会对我们的健康造成危害。研究人员对3万名成年人的数据进行了平均17年的跟踪调查，发现每天每多吃半个鸡蛋，都与患心脏病和死亡的风险显著相关。（他们限于受试者的饮食模式、整体健康状况和锻炼活动，以图将鸡蛋的影响独立出来。）“We found that, for every additional 300mg cholesterol person consumed, regardless of the food it came from, they had a 17% increased risk of cardiovascular disease, and 18% increased risk of all-cause mortality,” says Norrina Allen, one of the study’s authors and associate professor of preventive medicine at Northwestern University in Illinois, US.“我们发现，每多摄入300毫克胆固醇，不管它来自哪种食物，他们患心血管疾病的风险就增加17%，全因死亡率增加18%，”诺丽娜·艾伦说，她是这项研究的作者之一，美国伊利诺伊州西北大学预防医学副教授。Despite the study being one of the largest of its kind to address this specific relationship between eggs and heart disease, it was observational, giving no indication of cause and effect. It also relied upon a single set of self-reported data – participants were asked what they ate over the previous month or year, then followed up their health outcomes for up to 31 years. This means the researchers only got a single snapshot of what the participants were eating, even though our diets can change over time.尽管这项研究是解决鸡蛋和心脏病之间这种特殊关系的最大研究之一，但它是观察性研究，并没有给出因果关系的迹象。它还是依赖于一组自我报告的数据——参与者被问到他们在前一个月或前一年吃了什么，然后跟踪他们的健康结果长达31年。这意味着研究人员只是得到一份参与者正在吃什么的简单答案，尽管我们的饮食会随着时间的推移而改变。And the study conflicts with past results. Numerous studies suggest eggs are good for heart health. One previous analysis of half a million adults in China, published in 2018, even found the exact opposite: egg consumption was associated with lower risk of heart disease. Those who ate eggs every day had an 18% lower risk of death from heart disease and 28% lower risk of stroke death compared to those who didn’t eat eggs.研究结果与以往的研究结果相矛盾。许多研究表明鸡蛋有益于心脏健康。在2018年发表的一份针对中国50万成年人的分析报告中，甚至发现了完全相反的结果：食用鸡蛋与降低心脏病风险相关。与不吃鸡蛋的人相比，每天吃鸡蛋的人死于心脏病的风险降低18%，中风死亡的风险降低28%。Like the previous study, it too was observational – meaning it’s impossible to tease out cause and effect. (Do healthier adults in China simply eat more eggs, or do the eggs make them healthier?). That, of course, may be a big part of the confusion.和之前的研究一样，它也是观察性的研究，这意味着不可能理清因果关系。（在中国，健康的成年人只是多吃了鸡蛋，还是鸡蛋让他们更健康？）。当然，这可能是一个很大的困惑。While researchers are a long way from understanding why eggs affect us differently, the vast majority of recent research suggests they pose no risk to our health, and are much more likely to provide health benefits.虽然研究人员还很难理解为什么鸡蛋会对我们产生不同的影响，但最近的绝大多数研究表明，鸡蛋对我们的健康没有风险，而且更有可能为健康带来好处。Even so, having eggs for breakfast every day probably isn’t healthiest option, either – at least as it’s recommended we have a varied diet… rather than put all our eggs in one basket.即便如此，每天早餐都吃鸡蛋大概也不是最健康的选择——至少我们建议有多种饮食……而不是只有一种方式。 剪辑：BM︱翻译：Ray︱校对：Sally
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