是的，你可能天生就愛喝咖啡！

Most of us can't get going without a morning cup of Joe. But some people need two or three cups before they feel alert. What accounts for the difference? Genetics play a crucial role in the way you process coffee.

我們中的大多數(shù)人在早晨都需要一杯咖啡來提神，但是有些人卻需要更多(兩到三杯)才會感到清醒。是什么原因?qū)е铝诉@種差異呢?答案可能隱藏在你體內(nèi)。最近的研究表示，是基因使得每個人對咖啡的反應(yīng)有所差異。

A June 2018 report authored for the Institute for Scientific Information on Coffee by physician J.W. Langer found most coffee drinkers fall into one of three major groups, depending on the way they metabolize caffeine, the stimulant found in coffee.

今年6月，蘭格博士為咖啡科學信息研究所撰寫的一份報告表示：根據(jù)人們代謝咖啡因(咖啡中的興奮劑)的方式，大多數(shù)咖啡飲者可以被分為三大類。

Caffeine doesn't stay in our bodies but is metabolized (broken down) in the liver. The main enzyme in the liver that does this is called CYP1A2. Different people have different versions of this enzyme depending on their genetic makeup and the type you have determines how quickly or slowly caffeine remains in your liver. This genetic variability also affects the binding of caffeine to your brain receptors, which influences how alert or tired you feel after, say, one cup of coffee.

咖啡因被我們喝進去后，不會停留在我們的身體里，而是在肝臟中被代謝。肝臟中用于代謝咖啡因的主要酶被稱為CYP1A2，每個人的這種酶都有所差異，這取決于你的基因組成。而這種遺傳變異性也會影響咖啡因與大腦受體的結(jié)合，這便影響了你在喝完一杯咖啡后會有什么樣的反應(yīng)。

Here's how Dr. Langer broke down the three groups:
蘭格博士將人們大致分成以下三種：

High Sensitivity: These folks get wired from small amounts of caffeine and can have trouble sleeping because of this. Their livers metabolize caffeine at a snail’s pace, while their central nervous systems (comprising brain and spinal cord) go into high alert. Only a few people fall into this category.

對咖啡因高度敏感：這些人只需要少量的咖啡因就會興奮，并因此而難以入睡。他們的肝臟幾乎在以蝸牛的速度代謝咖啡因，而他們的中樞神經(jīng)系統(tǒng)只需要一點咖啡因就會進入高度警戒狀態(tài)。一般來說，只有少數(shù)人屬于這一類。

Regular Sensitivity: People in this category can down two to five cups a day and still sleep just fine — as long as they skip an evening dose.

對咖啡因常規(guī)敏感：這類人每天喝兩到三杯咖啡也依然可以睡得很好，只要他們不在晚上引用咖啡。

Low Sensitivity: These coffee drinkers metabolize caffeine very quickly. They can have several cups of coffee, and even a night-cap cup without feeling jittery or having their sleep disturbed. But to get the jolt of alertness from caffeine that people in the other two categories do, they have to drink a lot more coffee. (Health professionals caution against drinking more than five cups a day.)

對咖啡因低度敏感：這類人能夠很快地代謝咖啡因。他們每天都可以喝好幾杯咖啡，甚至在夜間飲用也不會影響到他們的睡眠。為了讓咖啡因使他們保持清醒，他們不得不喝更多的咖啡(健康專家提示最好不要超過5杯)。

"It's common for people to ask their doctor questions such as why they are kept awake by one cup of coffee, while their partner easily falls asleep after five cups," said Langer in a press statement. "The answer is that we are all unique coffee drinkers. Our genetic make-up programmes our reaction to caffeine, just as it programmes our hair colour and eye colour."

蘭格在一份新聞聲明中表示：“人們常常會問我，為什么一杯咖啡能讓他們保持清醒，而他們的伴侶在喝完五杯咖啡后仍然很容易睡著。答案就隱藏在我們的基因里，是我們的基因決定了我們對咖啡因的反應(yīng)，就像它影響我們眼睛的顏色一樣”。