It's time to go again to the A Moment of Science mailbag.
又到了抽取《科学一刻》信箱来信的时间了。
A listener writes:
一位听众这样写到：
Dear A Moment of Science,
亲爱的《科学一刻》栏目：
I keep hearing about how diet soda is bad for you.
我听说无糖汽水对身体有害。
This is troubling, since I drink lots of the stuff because has zero calories.
这可是件麻烦事，因为自从我听说无糖汽水不含热量后我就喝了很多。
So, is diet soda really bad? And if so, why?
所以说，无糖汽水真是有害的吗？如果是，那原因呢？
Well, the most accurate we can offer to the first question is “maybe.”
好了，我能给第一个问题最为精确的回答是“可能”。
As for why? We don't really know.
至于为什么？我实际上也不知道。

To elaborate, a few studies have found links between sweetened beverages including fruit drinks and regular and diet soda and depression.
确切的说，少有研究发现甜味饮料，包括果汁，含糖和无糖汽水与沮丧情绪有关。
For example, one study by researchers at the National Institutes of Health looked at survey data from more than 260,000 people.
例如，国立卫生研究院研究人员做了一项26万多人的调研，
Those who drank at least four cans of regular soda per day were 30 percent more likely to have been diagnosed with depression.
每天饮用超过四罐含糖汽水的人，就有30%被诊断出可能患有沮丧情绪症。
People who drank diet soda were even more prone to depression, at 31 percent.
31%饮用无糖汽水的人更容易情绪沮丧，
And people who drank four or more cans of fruit drinks were the most vulnerable, being 51 percent more likely to be diagnosed with depression.
饮用四罐或者更多果汁的人更加脆弱，高达51%的人可能会遭受沮丧情绪的困扰。
To be clear, the study found an association, not necessarily a causal link.
需要说明的是，这一研究找到的是相关性，而不是必然的因果联系。
In other words, it's not clear that drinking diet soda actually causes depression.
换句话说，还不清楚无糖汽水是否真的会导致情绪沮丧。
But it's also possible that something in sweetened drinks does in fact cause or at least raise the risk for depression.
但是，依然有可能的是甜饮料中的某些物质确实导致或者至少增加了情绪沮丧的风险。
More research will help sort that out.
更多研究将会支持这一结论。
So it seems reasonable to conclude that if you have a family history of depression, it may not be a bad idea to lay off sweetened drinks.
因此，似乎有理由认为，如果有抑郁症家族史的人，停止饮用甜味饮料可能不是个坏主意。
Even if studies have not proven that they trigger depression, there is a link.
即使研究没有证明它们能触发抑郁，但也据有相关性。