Countless¹ arguments have been waged over the superiority of one beverage² over the other. But what does the scientific evidence say?

关于这两种饮料孰优孰劣的问题已经引发了无数争论。但是科学证据是怎样的呢？

George Orwell may have written that "tea is one of the mainstays of civilization in this country"—but even we British have to acknowledge that our national drink is facing stiff competition from the espressos, cappuccinos, and lattes invading our shores.

乔治·奥威尔或许写过“茶是这个国家文明的一个支柱”这样的句子——但我们英国人也要承认，随着浓咖啡、卡布奇诺和拿铁侵入国门，我们的全民饮料正面临着激烈的竞争。

Despite the dangers of wading³ into such a charged argument, BBC Future decided⁴ to weigh up the relative merits of each drink. There's no accounting⁵ for taste, of course, but we have combed the scientific literature for their real, measurable effects on our body and mind.

尽管探讨这个敏感话题充满风险，“BBC未来”栏目还是决定对每种饮品的相对优点进行评估。当然，百人百味，但通过精心梳理科学文献，我们找出了它们对人体和大脑真实的、可测量的影响。

The wake-up call

醒脑剂

For many, the caffeine kick is the primary reason we choose either beverage; it's the oil to our engines when we're still feeling a bit creaky in the morning. Based purely⁶ on its composition, coffee should win hands down: a cup of tea has about half the dose (40 milligrams) of the stimulant⁷ caffeine that you would find in a standard cup of brewed⁸ filter coffee (80 to 115 milligrams). Yet this doesn't necessarily reflect the jolt⁹ of the wake-up call.

对许多人来说，咖啡因的兴奋作用是我们选择这两种饮料的主要原因；在睡眼惺忪的清晨，咖啡因就像石油一样，给我们身体的引擎以能量。只考虑成分的话，咖啡可以轻松获胜：一杯茶的咖啡因含量（40毫克）大约只有标准杯过滤咖啡（80至115毫克）的一半。然而，这并非反映了它们的醒脑作用。

Dosing subjects with either tea or coffee, one study found that both beverages¹⁰ left subjects feeling similarly alert later in the morning.

通过让被试者饮用一定量的茶或咖啡，一项研究发现，这两种饮料都能让受试者在早晨晚些时候感到同样清醒。

Verdict: Against logic¹¹, tea seems to provide just as powerful a wake-up call as coffee. It's a draw.

结论：虽然逻辑上讲不通，但茶跟咖啡的醒脑作用似乎不相上下。平局。

Sleep quality

睡眠质量

The biggest differences between coffee and tea may emerge once your head hits the pillow.

咖啡和茶之间最大的差异或许将集中体现在睡眠上。

Comparing people drinking the same volume of tea or coffee over a single day, researchers at the University of Surrey in the UK confirmed that although both drinks lend similar benefits to your attention during the day, coffee drinkers tend to find it harder to drop off at night—perhaps because the higher caffeine content finally catches up with you.

通过对比研究每天饮用等量的茶或咖啡的人，英国萨里大学的研究人员证实，尽管两种饮料在白天对注意力集中的作用差不多，但或许是因为咖啡里的咖啡因含量更高，喝咖啡的人晚上更难入睡。

Tea drinkers, in contrast, had longer and more restful slumbers¹².

相比之下，喝茶的人睡得更久更香。

Verdict: Tea offers many of the benefits of coffee, without the sleepless¹³ nights—a clear win.

结论：茶不仅拥有咖啡的许多好处，还不会带来不眠之夜——完胜。

Tooth staining

牙齿变黄

Along with red wine, coffee and tea are both known to turn our pearly whites a murky¹⁴ yellow and brown. But which is worse?

众所周知，红酒、咖啡和茶都会把洁白的牙齿慢慢染成暗黄色或棕褐色。但哪个最糟糕？

Most dentists seem to agree that tea's natural pigments¹⁵ are more likely to adhere to dental enamel¹⁶ than coffee's—particularly if you use a mouthwash containing the common antiseptic chlorhexidine, which seems to attract and bind¹⁷ to the microscopic¹⁸ particles.

大多数牙医似乎一致认为，茶中的天然色素比咖啡的更易附着于牙釉质之上——尤其当你使用常见的洗必泰漱口水时，其中的消毒洗必泰能吸引并聚合微观粒子。

Verdict: If you want a perfect smile, coffee may be the lesser¹⁹ of two evils.

结论：如果你想展现完美笑容，两害相权取其轻，咖啡也许还好一点。

A balm for troubled souls...

不安灵魂的慰藉……

In England, it's common to give "tea and sympathy" to a distressed²⁰ friend—the idea being that a cup of Earl Grey is medicine for troubled minds. In fact, there is some evidence that tea can soothe²¹ your nerves: regular tea drinkers do tend to show a calmer physiological²² response to unsettling situations (such as public speaking), compared to people drinking herbal infusions²³. Overall, people who drink three cups a day appear to have a 37% lower risk of depression than those who do not drink tea.

英国人喜欢给烦恼苦闷的朋友送去“茶与同情”——这是由于他们认为伯爵茶能够治愈不安的灵魂。事实上，有证据表明，茶可以舒缓神经：与喝中草药的人相比，经常饮茶者在处理一些令人不安的情况（如公开演讲）时确实表现得更为镇静。总的来说，每天喝三杯茶的人比不喝茶的人罹患抑郁症的风险要低37%。

Coffee doesn't have the same reputation; indeed, some report that it makes them feel like their nerves are jangling. Yet there is some evidence that it too may protect against long-term mental health problems. A recent "meta-analysis" (summarising the results of studies involving more than 300,000 participants) found that each cup of coffee a day seems to reduce your risk of developing depression by around 8%. In contrast, other beverages (such as sweetened soft drinks) only increase your risk of developing mental health problems.

咖啡并没有这种功效；事实上，有些人觉得咖啡会让人有些神经错乱。但是也有证据表明，咖啡能预防长期精神问题。最近的一项“荟萃分析”（总结了超过30万名参与者的研究结果）发现，每天一杯咖啡的人患抑郁症的风险比常人要低大约8%。相比之下，其他饮料（如甜味软饮）只会增加患精神疾病的风险。

Verdict: Based on this limited evidence, it's a draw.

结论：基于有限的证据，平局。

...and a balm for bodies...

身体的万金油

Similarly tantalising, though preliminary, epidemiological studies have suggested that both coffee and tea offer many other health-giving benefits. A few cups of either beverage a day appears to reduce your risk of diabetes²⁴, for instance.

流行病学研究虽然才刚刚起步，但也很吸睛。该领域研究表明，咖啡和茶都对身体还有其它益处。例如，每天喝几杯会降低患糖尿病的风险。

Both drinks also seem to moderately protect the heart, although the evidence seems to be slightly stronger for coffee, while tea also appears to be slightly protective against developing a range of cancers—perhaps because of its antioxidants.

饮用这两种饮料能对心脏起到一定的保护作用，尽管证据显示似乎咖啡的功效更强，但许是因为茶中的抗氧化剂，茶对预防癌症也有些许功效。

Verdict: Another draw—both drinks are a surprising, health-giving elixir²⁵.

结论：还是平局——这两种饮料都是神奇的、有益健康的灵丹妙药。

Overall verdict: Much as we Brits would have liked tea to come out the clear victor, we have to admit there is little between the two drinks besides personal taste. Based solely²⁶ on the fact that it allows you to get a better night's sleep, we declare tea the winner.

总结：大部分英国人都会觉得茶很明显更胜一筹。但除了个人口味，必须承认的是两者的差异并不大。仅仅基于能让人好眠这一点，茶无疑是赢家。