Is sugar really bad for you?

时间:2018-10-30 单词数:5990

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It’s hard to imagine now, but there was a time when humans only had access to sugar for a few months a year when fruit was in season. Some 80,000 years ago, hunter-gatherers ate fruit sporadically and infrequently, since they were competing with birds.


Now, our sugar hits come all year round, often with less nutritional value and far more easily – by simply opening a soft drink or cereal box. It doesn’t take an expert to see that our modern sugar intake is less healthy than it was in our foraging days. Today, sugar has become public health enemy number one: governments are taxing it, schools and hospitals are removing it from vending machines and experts are advising that we remove it completely from our diets.


But so far, scientists have had a difficult time proving how it affects our health, independent of a diet too high in calories. Meanwhile, there is also a growing argument that demonising a single food is dangerous – and causes confusion that risks us cutting out vital foods.


But both complex and simple carbohydrates are made up of sugar molecules, which are broken down by digestion into glucose and used by every cell in the body to generate energy and fuel the brain. Complex carbohydrates include wholegrains and vegetables. Simple carbohydrates are more easily digested and quickly release sugar into the bloodstream. They include sugars found naturally in the foods we eat, such as fructose, lactose, sucrose and glucose and others, like high fructose corn syrup, which are manmade.


Sweet nothings?


But again, it’s unclear if that means sugar actually causes heart disease or diabetes. Luc Tappy, professor of physiology at the University of Lausanne, is one of many scientists who argue that the main cause of diabetes, obesity and high blood pressure is excess calorie intake, and that sugar is simply one component of this.

但目前还不清楚糖是否真的导致了心脏病或糖尿病。包括瑞士洛桑大学生理学教授塔皮(Luc Tappy)在内的很多科学家认为,造成糖尿病、肥胖症和高血压的主要原因是热量摄入过量,糖只是热量的一种。

“More energy intake than energy expenditure will, in the long term, lead to fat deposition, insulin resistance and a fatty liver, whatever the diet composition,” he says. “In people with a high energy output and a matched energy intake, even a high fructose/sugar diet will be well tolerated.”


Tappy points out that athletes, for example, often have higher sugar consumption but lower rates of cardiovascular disease: high fructose intake can be metabolised during exercise to increase performance.


Overall, evidence that added sugar directly causes type 2 diabetes, heart disease, obesity or cancer is thin. Yes, higher intakes are associated with these conditions. But clinical trials have yet to establish that it causes them.


Sugar also has been associated with addiction… but this finding, too, may not be what it seems. A review published in the British Journal of Sports Medicine in 2017 cited findings that mice can experience sugar withdrawal and argued that sugar produces similar effects to cocaine, such as craving. But the paper was widely accused of misinterpreting the evidence. One key criticism was that the animals were restricted to having sugar for two hours a day: if you allow them to have it whenever they want it, which reflects how we consume it, they don’t show addiction-like behaviours.


Still, studies have demonstrated other ways in which sugar affects our brains. Matthew Pase, research fellow at Swinburne’s Centre for Human Psychopharmacology in Australia, examined the association between self-reported sugary beverage consumption and markers of brain health determined by MRI scans. Those who drank soft drinks and fruit juices more frequently displayed smaller average brain volumes and poorer memory function. Consuming two sugary drinks per day aged the brain two years compared to those who didn’t drink any at all. But Pase explains that since he only measured fruit juice intake, he can’t be sure that sugar alone is what affects brain health.

但还有很多研究表明,糖会以其他方式影响我们的大脑。澳大利亚斯威本大学人类精神药理学中心的研究员帕塞(Matthew Pase)请被试对象报告他们喝了多少含糖饮料,并用核磁共振扫描他们大脑的健康状况,研究了摄入量与大脑健康的关系。喝汽水和果汁频率更高的人,平均脑容量更小,记忆力更差。每天喝两杯含糖饮料的人大脑比完全不喝的人老两岁。但帕塞说,他只测算了果汁的摄入量,因此无法确定影响大脑健康的是不是只有糖。