這個話題是一個很有意思的主題，BBC也發表了一篇看法…

喬治·奧威爾(George Orwell)曾經寫過這樣一段話：「茶是英國的一大文明支柱。」然而，就連英國人自己也承認，我們的國飲正在面臨各種咖啡發起的挑戰。
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.

儘管捲入這種火藥味甚濃的競爭，可能面臨許多風險，但BBC Future還是決定對這兩種飲品的相關指標展開一番對比。當然，從口味上講，實在是眾口難調，但我們還是梳理了各種科學文獻，查找這兩種飲品對我們身心健康產生的實際量化影響。
Despite the dangers of wading into such a charged argument, BBC Future decided to weigh up the relative merits of each drink. There’s no accounting for taste, of course, but we have combed the scientific literature for their real, measurable effects on our body and mind.

1.提神作用 / The wake-up call

咖啡因是很多人選擇這兩種飲料的主要原因；當我們早晨醒來依舊感覺困乏時，它可以充當我們身體引擎的潤滑油。單純從成分來看，咖啡在這方面遙遙領先：一杯茶的咖啡因含量約為一杯標凖的發酵過濾咖啡的一半，前者為40毫克，後者為80至115毫克。然而，這未必能反映真實的提神作用。
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 purely on its composition, coffee should win hands down: a cup of tea has about half the dose (40 milligrams) of the stimulant caffeine that you would find in a standard cup of brewed filter coffee (80 to 115 milligrams). Yet this doesn’t necessarily reflect the jolt of the wake-up call.

「咖啡因的含量並不能反映全貌：我們的預期或許也會對自身的感受產生影響。」
Caffeine dose is not the whole story: perhaps our expectations also determine how alert we feel

有一項小規模的研究顯示，當志願者早晨喝過了茶或咖啡後，這兩種飲料在隨後的時間內產生的提神作用非常相似。儘管這項研究完全依靠志願者自己報告的感受，但反應時間等更加客觀的指標同樣未能顯示出明顯差異。事實上，當你大量飲用茶水，使之達到與咖啡等效的強度時，提神作用反而更加明顯。
Dosing subjects with either tea or coffee, one (admittedly small) study found that both beverages left subjects feeling similarly alert later in the morning. Although that study was based on self-reported feelings of alertness, clear differences have failed to emerge in more objective measures of concentration, either – such as reaction times. Indeed, when you dose up on tea made to the equivalent strength as coffee, it actually proves to be more effective at sharpening the mind.

科學家就此認定，咖啡因含量並不能反應全貌：我們的預期或許也會對自身感受產生影響，也有可能是因為我們喜歡的味道和氣味，喚醒了我們的意識。
The scientists conclude that the caffeine dose is not the whole story: perhaps our expectations also determine how alert we feel, or it could be that it’s the overall experience of the tastes, and smells, of our favourite drink that awakens our senses.

結論：與邏輯相悖的是，茶的提神作用與咖啡相同。二者打平。
Verdict: Against logic, tea seems to provide just as powerful a wake-up call as coffee. It’s a draw.

2.睡眠質量 / Sleep quality

當你凖備入睡時，咖啡和茶之間的最大差異或許才能真正體現出來。
The biggest differences between coffee and tea may emerge once your head hits the pillow.

英國薩里大學(University of Surrey)的研究人員，對比了同一天內攝入等量茶水或咖啡的人後發現，儘管這兩種飲品對於集中白天的注意力都發揮了類似的作用，但喝咖啡的人在夜間往往更難入睡——或許是因為較高的咖啡因含量最終開始對你起作用。
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.

相比而言，喝茶的人睡眠時間更長，狀態也更加放鬆。
Tea drinkers, in contrast, had longer and more restful slumbers.

結論：茶可以提供很多與咖啡相同的益處，但卻不會引發失眠——在這一局中明顯勝出。
Verdict: Tea offers many of the benefits of coffee, without the sleepless nights – a clear win.

3.牙齒著色 / Tooth staining

牙科醫生表示，茶的天然染料比咖啡更容易附著在牙釉質上(圖片來源：Getty Images) Tea’s natural pigments are more likely to adhere to dental enamel than coffee’s, dentists say (Credit: Getty Images)

與紅酒一樣，咖啡和茶也都會給潔白的牙齒染上一層暗淡的黃色或棕色。但哪一種飲品的著色力更強呢？
Along with red wine, coffee and tea are both known to turn our pearly whites a murky yellow and brown. But which is worse?

多數牙醫的意見似乎都很統一，他們認為，茶的天然染料比咖啡更容易附著在牙釉質上——尤其是當你使用的漱口水中包含洗必泰這種常見的抗菌劑時，這種物質似乎能夠吸引並附著在微觀粒子上。
Most dentists seem to agree that tea’s natural pigments are more likely to adhere to dental enamel than coffee’s – particularly if you use a mouthwash containing the common antiseptic chlorhexidine, which seems to attract and bind to the microscopic particles.

結論：如果你想擁有完美的笑容，那麼兩害相權取其輕，咖啡可能更適合你。
Verdict: If you want a perfect smile, coffee may be the lesser of two evils.

4.安神作用 / A balm for troubled souls…

在英格蘭，人們往往都會使用「茶水和同情」來安慰心情苦悶的朋友，他們認為，一杯伯爵茶可以治療受傷的心。事實上，的確有證據表明茶可以起到安神的作用：與喝洋柑橘薄荷茶的人相比，經常喝茶的人在面對令人不安的環境時(例如公開演講)，往往表現得更加鎮靜。整體而言，一天喝3杯茶的人患抑鬱症的風險比不喝茶的人降低37%。
In England, it’s common to give “tea and sympathy” to a distressed friend – the idea being that a cup of Earl Grey is medicine for troubled minds. In fact, there is some evidence that tea can soothe your nerves: regular tea drinkers do tend to show a calmer physiological response to unsettling situations (such as public speaking), compared to people drinking herbal infusions. Overall, people who drink three cups a day appear to have a 37% lower risk of depression than those who do not drink tea.

「有證據表明茶可以起到安神的作用。」
There is some evidence that tea can soothe your nerves

咖啡卻沒有這樣的效果，甚至有報告顯示，咖啡會讓人神經緊張。但也有一些證據表明，這種飲品同樣有益於保持長期心理健康。最近的「元分析」(匯總了30多萬參與者的研究結論)發現，每天喝一杯咖啡似乎能將患抑鬱症的風險降低8%。相比而言，其他飲品(例如甜味軟飲料)只會增加心理健康問題發生的風險。
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.

薩里大學的研究人員發現，喝咖啡的人在夜間往往更難入睡 University of Surrey researchers found that coffee drinkers tend to find it harder to drop off to sleep at night (Credit: iStock)

我們需要有保留地看待這個問題：儘管科學家已經盡力，但在這種大規模流行病研究中，卻很難排除其他影響因素——不過，這兩種飲品可能都提供了一些營養成分，可以降低應激反應，並促進長期心理健康。
We need to take such results with a pinch of salt: despite the scientists’ best efforts, in this kind of large epidemiological study it’s hard to rule out other factors that may be behind the link – but it could be that both drinks offer a cocktail of nutrients that dampen down stress responses and boost mood in the long-term.

結論：從有限的證據來看，這一局打平。
Verdict: Based on this limited evidence, it’s a draw.

5.有益身體健康 / …and a balm for bodies

同樣也有一些值得關注的初步研究表明，咖啡和茶都有許多其他有益健康的好處。例如，每天喝幾杯咖啡或茶水都能降低患糖尿病的風險。但具體能帶來多大好處仍然沒有定論，目前的估計在5%至40%之間。不過，由於無咖啡因的咖啡也能起到同樣的作用，所以可能是其他營養成分改善了新陳代謝，使之仍然可以高效地處理血糖，而不會對胰島素感到遲鈍——這正是糖尿病的成因。
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 diabetes, for instance. (The exact size of the benefit is still under discussion – estimates vary from around 5 to 40%.) Since even decaf coffee confers the same benefits, it seems likely that other nutrients may be oiling the metabolism so that it can still efficiently process blood glucose without becoming insensitive to insulin – the cause of diabetes.

「每天喝幾杯咖啡或茶水似乎都能降低患糖尿病的風險。」 A few cups of either beverage a day appears to reduce your risk of diabetes

這兩種飲品似乎也都能對我們的心臟起到一定的保護作用，但咖啡的證據略微明確一些。不過，茶似乎在預防一系列癌症方面效果更好——這可能源自它所富含的抗氧化劑。
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.

結論：再次打平——這兩種飲品都有益身體健康。
Verdict: Another draw – both drinks are a surprising, health-giving elixir.

總結：由於英國人更希望茶能勝出，所以不得不承認，在比較這兩種飲品的過程中的確存在一些個人偏好。單純從有益睡眠的角度來看，我們認為茶比咖啡更好。
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 solely on the fact that it allows you to get a better night’s sleep, we declare tea the winner – but why not share your own thoughts with us through social media?

資料來源：BBC
編輯：E.L.