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《糖，何时变成了全民公敌？ 》
How Sugar Became Public Enemy No. 1
Many experts believe that sweetened foods have caused a global health crisis. What’s so bad about sugar? Here’s everything you need to know:
Why is sugar in the spotlight?
For years, dieticians have warned us to steer clear of1) fat and cholesterol2)—the two food evils long believed to be fueling the West’s obesity, diabetes, and heart disease epidemics3).
But a growing number of nutritionists are now pointing the finger at sugar, arguing that our overconsumption of sodas, candy, cookies, and other sweets and processed foods is the real cause of our health crisis. Some go even further, arguing that sugar is an addictive “poison” that causes a whole host of degenerative4) ailments—including cancer—even in thin people. Evidence has emerged that shows the sugar industry may have downplayed5) those risks for profit—turning the modern Western diet into the sweetest in human history.
“We’re in a whole new world of sugar consumption,” says Barry Popkin, professor of nutrition at the University of North Carolina. “We don’t really know what that means for our health.”
How much sugar do we consume?
The average American adult downs 22 teaspoons of the stuff a day, the average child 32. The World Health Organization recommends just six teaspoons a day. Added sugars—those not found naturally in fruit and vegetables, like table sugar and high-fructose6) corn syrup7)—began to proliferate in the Western diet in the mid-20th century, just as scientists were starting to discover links between sugar and heart disease.
The sugar industry decided to push back against this research, adopting the aggressive tactics of Big Tobacco8). First, as memos uncovered last September reveal, an industry group paid three Harvard nutritionists $6,500—about $50,000 today—to divert the blame. In a 1967 New England Journal of Medicine article, the nutritionists discounted the evidence against sugar and concluded there was “no doubt” the best way to prevent heart disease was to reduce cholesterol and saturated fat. “This is quite what we had in mind,” one sugar industry executive said when he saw the article.
What did Big Sugar do next?
The industry launched an aggressive advertising campaign in the 1970s to convince Americans that sugar actually helps you lose weight by suppressing the appetite. “Sugar can be the willpower you need to undereat,” one ad asserted; another recommended eating a cookie before lunch each day. That campaign, combined with work by the Harvard researchers, helped muddy9) the scientific waters enough to keep dietary sugar guidelines vague. The American Heart Association approved of added sugar as part of a healthy diet, and millions of Americans embraced low-fat, high-sugar diets. Consumption of added sugars soared 30 percent between 1977 and 2010. It’s no coincidence, many nutritionists say, that obesity rates more than doubled over that same period.
Why is sugar so bad for us?
Scientists have found that refined sugar, which is made up of fructose and glucose carbohydrates10), is harder to metabolize11) than the purely glucose-based carbohydrates found in potatoes and other starches12). While glucose is converted into energy by every cell in the body, fructose is mainly metabolized in liver cells. When a person consumes too much fructose, many nutritionists say, the liver becomes overwhelmed and begins converting it into fat, some of which gathers in the liver. An accumulation of fat in the liver can cause insulin resistance13), which disrupts the body’s ability to maintain stable levels of blood sugar and fat, leading to heart disease and diabetes. Anti-sugar advocate Gary Taubes contends that insulin resistance is a primary driver of obesity, and can also give rise to dementia14) and some cancers. “If I’m right about sugar,” says Taubes, “then it’s more harmful ultimately than smoking.”
Do all nutritionists agree?
No. Some, including Fred Brouns, professor of Health Food Innovation at Maastricht University in the Netherlands, argue that sugar’s effects remain “poorly investigated and highly controversial.” The problem with all nutritional science is that it’s difficult to monitor diets over the years-long time span needed to track the causes of degenerative diseases. But there’s no doubt that we’re lacing15) modern supermarket food with concentrated sugar in a way that isn’t replicated in nature. Kimber Stanhope, a nutritional biologist at University of California-Davis, ordered her staff to eat enough fruit to get 25 percent of their daily calories from sugar—the quantity she has shown raises the level of artery16)-clogging triglycerides17) in the blood. Four out of seven of the subjects had to quit. “It was more fruit than they could bear to eat,” says Stanhope. Yet you can easily get that same amount of sugar by washing down18) a couple of brownies with a can of Coke.
What can be done?
Individuals can choose to limit their sugar intake—but that requires avoiding nearly all processed foods. Public officials are also trying to nudge society at large toward making healthier choices. In the 2016 election, three California cities passed ballot19) measures imposing taxes on sugary sodas. But conservatives largely oppose these so-called sin taxes, arguing that people should have the freedom to do what they want to their bodies. To cut down on sugar, some people have switched to zero-calorie artificial sweeteners, like the saccharin20)-based Sweet ’N Low21). But little is known about the long-term effects of these chemical substitutes on the body. And because such products can be up to 13,000 times sweeter than sugar, they can trick the body into craving even more calories. “Don’t be fooled,” says metabolism researcher Susan Swithers. “We were once led to believe that ‘light’ and ‘low tar’ cigarettes are better choices than regular cigarettes,” she says. “Neither choice is actually healthy.”
America’s favorite drug
Sugar is everywhere. Eighty percent of supermarket foods contain it—and purportedly “savory22)” foods often contain more sugar than sweet treats like ice cream. Whole-wheat bread can have a teaspoon of sugar per slice; Heinz tomato ketchup23) contains 22.8 percent sugar, twice as much as Coca-Cola. As we swamp our bodies with sugar, we only become more addicted. A 2016 study in Nature Neuroscience suggested that sugar hijacks the brain by triggering its reward system, pushing the body to ask for more and more. Sugar might even be more addictive than recreational drugs24), says cardiovascular research scientist James DiNicolantonio. “When you look at animal studies comparing sugar to cocaine, even when you get the rats hooked on intravenous25) cocaine, once you introduce sugar, almost all of them switch to the sugar.”
许多专家认为加糖食品引起了一场全球健康危机。糖到底有什么坏处？你需要知道的都在这里：
糖为何会成为焦点？
多年来，饮食保健专家一直警告我们要远离脂肪和胆固醇——这两种食品恶魔长期以来一直被视作是西方肥胖症、糖尿病以及心脏病流行的幕后推手。但现在越来越多的营养学家将矛头指向了糖，他们认为健康危机的真正原因是我们食用了过量的碳酸饮料、糖果、饼干以及其他甜品和加工食品。有的把问题说得更严重，认为糖是一种让人上瘾的“毒药”，导致了包括癌症在内的大量变性性疾病，连瘦人也难以幸免。有证据表明制糖业为了获取利润，可能将这些风险轻描淡写，近代西方的饮食也因此达到了人类历史上最甜的程度。北卡罗来纳州大学营养学教授巴里·波普金说：“在糖的消耗方面我们正处于一个全新的世界。我们并不确定这对健康而言意味着什么。”
人们食用的糖量有多少？
每个美国成年人日均食用22茶匙糖，儿童食用32茶匙。而世界卫生组织建议的日食用量仅为6茶匙。添加糖于20世纪中期广泛出现在西方的食品中，添加糖是指那些不是在水果或蔬菜中天然形成的糖，比如砂糖和高果糖玉米糖浆。几乎同时，科学家们开始揭开糖与心脏病之间的关系。制糖业决定像大型烟草公司一样采取主动出击的策略，推迟这项研究。去年9月份披露的备忘录显示，首要的措施是由一个行业团体向三名哈佛大学的营养学家支付6,500美元(相当于现在的50,000美元)，从而转移人们指责的目标。在《新英格兰医学杂志》1967年发表的一篇文章中，这几名营养学家对那些不利于糖的证据持怀疑态度，并做出定论认为，预防心脏疾病的最佳方法“毫无疑问”是减少摄入胆固醇和饱和脂肪。一名制糖业主管看到这篇文章后说：“这正是我们想说的。”
制糖业巨头之后还干了什么？
制糖业在20世纪70年代发起了一轮强劲的广告攻势，努力让美国民众相信，糖实际上能通过降低食欲帮助人们减肥。一则广告声称：“糖是您减少食量所需的精神支柱。”另一则广告则建议每天午饭前吃一块曲奇饼干。这一轮攻势加上哈佛大学研究人员的工作，在科学上混淆了视听，使得关于糖的饮食指南一直处于含糊不清的状态。美国心脏病协会认可添加糖是健康饮食的一部分，数百万美国人接受了低脂高糖的饮食。1977年至2010年期间，添加糖的食用量陡增了30%。许多营养学家认为，肥胖率在这一时间翻了一倍还多并不是偶然。
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文章摘自：《新东方英语》杂志2017年7月号
