苏打水损伤大脑无糖饮料更糟

[原文来自：www.ii77.com]

[好文分享：www.ii77.com]

根据美国农业部的数据，2016年美国人共消耗了近1100万吨糖，其中大部分是运动饮料和苏打水等含糖饮料。

研究表明，摄入过量的糖──尤其是含糖饮料中的果糖，可能会损害大脑。

研究人员使用弗雷明汉心脏研究（Framingham Heart Study，FHS）的数据发现，常喝含糖饮料的人记忆力较差，脑容量变小，同时大脑中负责学习和记忆的海马体明显缩小。更糟的是，进一步的研究发现，每天喝无糖苏打水（diet soda）的人，比那些不喝的人患中风和痴呆症的概率要高出3倍。

这两项研究分别发表在学术期刊《阿尔茨海默病与痴呆》和《中风》上。

但研究人员同时也指出，这些发现，只证明了相关性（correlation），并非因果关系。因此研究者在警告人们不要过量饮用无糖苏打水或含糖饮料的同时，也指出需要做更多的研究以确定它们是如何损害大脑，以及它们如何令糖尿病或各种血管疾病更加恶化。

“这些研究虽然不是包罗万象或终结性的，但它们提供了强有力的数据和强烈的建议。”同为这两篇研究论文的资深作者Sudha Seshadri说：“看来含糖饮料实在没什么好处，用人造甜味剂代替似乎也并无助益。”她又补充说，也许我们还是应该喝水。

两篇论文的通讯作者帕斯（Matthew Pase）说，过量的糖一向与肥胖，心脏病和二型糖尿病等心血管和代谢疾病有关，但人们对其对大脑的影响知之却甚少。

他选择研究含糖饮料来检查糖消费总量，因为“很难衡量饮食中的糖摄入总量，”他说：“因此使用含糖饮料代替之。”

第一项研究分析了约四千人的数据，包括核磁共振成像（MRI）扫描和认知测试结果，并把研究对象分为两组：每天饮用超过两杯含糖饮料者，或每周喝超过三杯苏打水的人。在“高摄入量”组中，发现了多种加速脑老化的迹象，包括较小的整体脑容量，较差的情景记忆和萎缩的海马体，这些均为早期阿尔茨海默病的危险征兆。还发现，每天至少喝一杯苏打水的人，和脑容量减少相关。

第二项研究调查同类疾病患者45岁以上的后代，对其做了10年的监测后发现，喝含糖饮料和中风、脑痴呆并无关联。然而，每天至少喝一杯无糖苏打水（diet soda）者更可能患上以上两种疾病。

以往的研究发现无糖苏打水者可能引起中风，而导致脑痴呆这还是头一回。他补充说，这些研究没有区分人造甜味剂的类型，也没有考虑其它可能来源，他说，科学家已经提出了人造甜味剂造成伤害的各种假设，从改变肠道细菌到改变大脑对“甜蜜”的看法，但“我们需要继续研究以找出其潜在机制。”

By American Heart Association News

Source:A diet soda a day might affect dementia risk, study suggests

One or more artificially sweetened drinks a day was associated with higher risk of stroke and dementia, a new study suggests.

The research, published Thursday in the science journal Stroke, examined consumption of beverages sweetened with sugarand artificial sweeteners but did not find that same association with sugary beverages. The results, however, come with a host of caution flags raised by experts. They say the study does not even hint that regular sugary drinks directly cause strokes or dementia.

The study’s lead author said the observational study shows an association or trend in a group of people and not a direct cause-and-effect link. It’s more “hypothesis-generating.”

“The jury is still out, and this just shows people need to be cautious,” said Matthew Pase, Ph.D., a fellow in the department of neurology at Boston University School of Medicine and an investigator at the Framingham Heart Study.

Previous studies have looked at artificial sweeteners’ impact on stroke risk. Pase believes this is the first study to look at its association with risk of dementia – and he hopes the work will spur more research into the effects of these sweeteners on the brain.

Researchers analyzed the self-reporteddiets of two sets of people participating in the Framingham Heart Study, the longest-running heart study in the U.S., funded by the National Heart, Lung,and Blood Institute and run in partnership with Boston University. The study examined beverage intake of 2,888 people over the age of 45 for its stroke analysis and 1,484 people over the age of 60 for the study’s dementia analyses.

Over seven years, researchers used food frequency questionnaires up to three different points in time. They then followed up for the next 10 years to determine who developed stroke and dementia.

At the end of the follow-up period,researchers counted 97 strokes, or 3 percent of the participants in the stroke analysis arm of the study. Of those, 82 were ischemic. The study found 81 casesof dementia, or 5 percent of the participants in the dementia arm of the study.Of those, 63 were diagnosed as Alzheimer’s disease.

The study found that people who reported drinking at least one artificially sweetened drink a day compared with lessthan one a week were 2.96 times as likely to have an ischemic stroke, caused by blood vessel blockage, and 2.89 times as likely to be diagnosed with dementia due to Alzheimer’s disease. The results were adjusted for variables such asage, sex, caloric intake, diet quality, physical activity and smoking.

Pase and other researchers say the work points clearly to the need to investigate the possible biological reasons artificial sweeteners might affect the brain and the need for more experimental and clinical trials.

“We need to be cautious in the interpretation of these results,” said Rachel K. Johnson, Ph.D., past chair ofthe American Heart Association’s Nutrition Committee and professor of nutritionat the University of Vermont. “It doesn’t prove cause and effect. When you see these kinds of associations, you want to always ask what is the biological plausibility, what is the mechanism that might be causing this?”

But, Johnson said, there is a part of the issue that is “settled science.”