Picture warm, gooey cookies, crunchy candies, velvety cakes, waffle cones piled high with ice cream. Is your mouth watering? Are you craving dessert? Why? What happens in the brain that makes sugary food so hard to resist?
想像溫暖、甜黏的餅乾、 脆脆的糖果、滑順的蛋糕、高疊著冰淇淋的餅乾甜筒。你的嘴巴在滴口水了嗎？你渴望甜點了嗎？為什麼？腦袋裡發生什麼事讓甜食如此難以抗拒？
Sugar is a general term used to describe a class of molecules called carbohydrates, and it's found in a wide variety of food and drink. Just check the labels on sweet products you buy. Glucose, fructose, sucrose, maltose, lactose, dextrose, and starch are all forms of sugar, so are high-fructose corn syrup, fruit juice, raw sugar, and honey. And sugar isn't just in candies and desserts, it's also added to tomato sauce, yogurt, dried fruit, flavored waters, or granola bars. Since sugar is everywhere, it's important to understand how it affects the brain. What happens when sugar hits your tongue? And does eating a little bit of sugar make you crave more?
糖是一個用來形容一類被稱做碳水化合物的分子的統稱，而它能在多種食物及飲料中被發現。只要看看你買的甜食上的標籤。葡萄糖、果糖、蔗糖、麥芽糖、乳糖、右旋糖、及澱粉都是糖的型態，高果糖玉米糖漿、果汁、粗糖、和蜂蜜也是。而糖不只存在糖果及甜點裡，它也被加進蕃茄醬、優格、果乾、調味水、或燕麥棒裡。既然糖無所不在，了解它如何影響腦部就很重要了。當糖碰撞你的舌頭時發生什麼事？吃少許的糖會讓你想要更多嗎？
You take a bite of cereal. The sugars it contains activate the sweet taste receptors, part of the taste buds on the tongue. These receptors send a signal up to the brain stem, and from there, it forks off into many areas of the forebrain, one of which is the cerebral cortex. Different sections of the cerebral cortex process different tastes—bitter, salty, umami, and in our case, sweet. From here, the signal activates the brain's reward system. This reward system is a series of electrical and chemical pathways across several different regions of the brain. It's a complicated network, but it helps answer a single subconscious question, "Should I do that again?"
你吃一口榖片。它所含的糖觸發甜味受器－－那是舌頭上味蕾的一部份。這些受器上傳一個信號到腦幹，而從那裡，信號分散至前腦眾多區域內，其中之一是大腦皮層。大腦皮層的不同區域處理不同的味道－－苦味、鹹味、鮮味、以及在我們的例子中：甜味。從大腦皮層這，信號啟動腦部的酬償系統。這套酬償系統是一連串通過大腦各個不同區域的電子及化學途徑。這是一個複雜的網絡，但這協助回答一個唯一的潛意識問題：「我應該再做一次嗎？」
That warm, fuzzy feeling you get when you taste Grandma's chocolate cake? That's your reward system saying, "Mmm...yes!" and it's not just activated by food. Socializing, sexual behavior, and drugs are just a few examples of things and experiences that also activate the reward system. But over-activating this reward system kick-starts a series of unfortunate events—lost of control, craving, and increased tolerance to sugar.
當你吃到外婆的巧克力蛋糕那溫暖、飄飄然的感覺是什麼？那是你的酬償系統在說：「嗯....好極了!」而這不單單由食物觸發。社交、性行為、以及毒品僅是幾個亦能啟動酬償系統的範例事物及體驗。但過度激化此酬償系統開啟一連串不幸的事件－－失控、渴望、以及對糖增加的耐受性。
Let's get back to our bite of cereal. It travels down into your stomach and eventually into your gut. And guess what? There are sugar receptors here, too. They're not taste buds, but they do send signals telling your brain that you're full, or that your body should produce more insulin to deal with the extra sugar you're eating.
讓我們回到我們吃的那口榖片。 它向下移動進入你的胃部，最終進到你的腸子。然後猜猜怎麼著？這裡也有糖類受器。它們不是味蕾，但它們確實會傳送信號告訴你的大腦你吃飽了，或者你的身體應該要製造更多胰島素來應付你吃下的額外糖類。
The major currency of our reward system is dopamine, an important chemical or neurotransmitter. There are many dopamine receptors in the forebrain, but they're not evenly distributed. Certain areas contain dense clusters of receptors, and these dopamine hotspots are a part of our reward system. Drugs like alcohol, nicotine, or heroin send dopamine into overdrive, leading some people to constantly seek that high, in other words, to be addicted. Sugar also causes dopamine to be released, though not as violently as drugs. And sugar is rare among dopamine-inducing foods. Broccoli, for example, has no effect, which probably explains why it's so hard to get kids to eat their veggies.
我們酬償系統中的主要流通媒介為多巴胺－－一種重要的化學物質，或神經傳遞素。在前腦中有許多多巴胺受器，但它們並未平均分佈。特定區域含有稠密的受器叢，而這些多巴胺熱點是我們酬償系統的一部分。像是酒精、尼古丁、或海洛因的毒品促使多巴胺過度活躍，導致有些人持續地追尋那種快感，換言之，變得上癮。糖類也致使多巴胺釋放，雖然不像毒品那般劇烈。而糖分在引發多巴胺的食物中是罕見的。花椰菜，舉例來說，就沒有甜味的效果，這或許解釋了為什麼要小孩吃他們的蔬菜會那麼困難。
Speaking of healthy foods, let's say you're hungry and decide to eat a balanced meal. You do, and dopamine levels spike in the reward system hotspots. But if you eat that same dish many days in a row, dopamine levels will spike less and less, eventually leveling out. That's because when it comes to food, the brain evolved to pay special attention to new or different tastes. Why? Two reasons.
提到健康食物，假設你現在餓了且決定吃均衡的一餐。你真的吃了，而多巴胺的量在酬償系統熱點中暴增。但若是你連續好幾天吃同樣的餐點，多巴胺量就會增加得越來越少，最終達到平穩狀態。那是因為當提到食物，大腦演化成對新鮮或是不同的味道特別關注。為什麼呢？兩個原因。
First, to detect food that's gone bad. And second, because the more variety we have in our diet, the more likely we are to get all the nutrients we need. To keep that variety up, we need to be able to recognize a new food, and more importantly, we need to want to keep eating new foods. And that's why the dopamine levels off when a food becomes boring. Now back to that meal. What happens if in place of the healthy, balanced dish, you eat sugar-rich food instead?
第一，察覺已經壞掉的食物。而第二，因為我們的飲食有越多種類，我們就越可能得到我們所需的所有營養。為了要保持種類多樣化， 我們要能認出一樣新食物，更重要的是，我們得想要一直吃新食物。而那就是為何當一樣食物變得無趣時，多巴胺會趨向平穩。現在回到那一餐。如果取代健康、均衡的餐點，你反而吃下高糖食物，會發生什麼事？
If you rarely eat sugar, or don't eat much at a time, the effect is similar to that of the balanced meal. But if you eat too much, the dopamine response does not level out, in other words, eating lots of sugar will continue to feel rewarding. In this way, sugar behaves a little bit like a drug. It's one reason people seem to be hooked on sugary foods. So think back to all those different kinds of sugar. Each one is unique, but every time any sugar is consumed, it kick-starts a domino effect in the brain that sparks off a rewarding feeling, too much, too often, and things can go into overdrive. So yes, over-consumption of sugar can have addictive effects on the brain. But a wedge of cake once in a while won't hurt you.
如果你鮮少吃糖，或一次沒有吃太多，其效果會和均衡的一餐雷同。但如果你吃過多，多巴胺反應並不會回穩，也就是說，吃太多的糖會持續感到滿足。這樣一來，糖表現得就有點像一種毒品。這是一種人們似乎著迷於甜食的原因。那麼回想那各種類的糖。每一種都是獨特的，但每次任何糖類被攝取，它都啟動大腦中引起一種回饋感的骨牌效應，太過量、太頻繁，一切可能走向超載。所以是的，過度攝取糖分可能對腦部有成癮效果。但偶爾一塊蛋糕不會害到你。
- 「分散至」- Fork Off
These receptors send a signal up to the brain stem, and from there, it forks off into many areas of the forebrain...
這些受器上傳一個信號到腦幹，而從那裡，信號分散至前腦眾多區域內... - 「猜猜怎麼了」- Guess What
And guess what? There are sugar receptors here, too.
然後猜猜怎麼著？這裡也有糖類受器。 - 「比方說、假設」- Let's Say
Speaking of healthy foods, let's say you're hungry and decide to eat a balanced meal.
提到健康食物，假設你現在餓了且決定吃均衡的一餐。 - 「一連串、連續」- In A Row
But if you eat that same dish many days in a row, dopamine levels will spike less and less, eventually leveling out.
但若是你連續好幾天吃同樣的餐點，多巴胺量就會增加得越來越少，最終達到平穩狀態。 - 「變得平穩」- Level Out
But if you eat that same dish many days in a row, dopamine levels will spike less and less, eventually leveling out.
但若是你連續好幾天吃同樣的餐點，多巴胺量就會增加得越來越少，最終達到平穩狀態。 - 「變得平穩」- Level Off
And that's why the dopamine levels off when a food becomes boring.
而那就是為何當一樣食物變得無趣時，多巴胺會趨向平穩。 - 「代替」- In Place Of
What happens if in place of the healthy, balanced dish, you eat sugar-rich food instead?
如果取代健康、均衡的餐點，你反而吃下高糖食物，會發生什麼事？ - 「換句話說、也就是說」- In Other Words
But if you eat too much, the dopamine response does not level out, in other words, eating lots of sugar will continue to feel rewarding.
但如果你吃過多，多巴胺反應並不會回穩，也就是說，吃太多的糖會持續感到滿足。 - 「導致」- Spark Off
...it kick-starts a domino effect in the brain that sparks off a rewarding feeling...
...它都啟動大腦中引起一種回饋感的骨牌效應... - 「偶爾」- Once In A While
But a wedge of cake once in a while won't hurt you.
但偶爾一塊蛋糕不會害到你。
