How sugar affects the brain - Nicole Avena

糖類如何影響大腦 - 尼可．愛薇娜 (Nicole Avena)

譯者: Hao-Wei Chang 審譯者: Dong Mao

Picture warm, gooey cookies,

想像一個溫熱、黏膩的餅乾

crunchy candies, velvety cakes,

爽脆的糖果

細緻可口的蛋糕

waffle cones piled high with ice cream.

甜筒上堆起的冰淇淋球

Is your mouth watering?

讓你口水直流了嗎？

Are you craving dessert?

讓你想吃點心了嗎？

Why?

為什麼？

What happens in the brain that makes sugary foods so hard to resist?

是什麼讓你的腦子

無法抗拒含糖食物呢？

Sugar is a general term used to describe a class of molecules

糖是對

碳水化合物分子的

總稱

called carbohydrates,

and it's found in a wide variety of food and drink.

而它們存在許多食物、飲料中

Just check the labels on sweet products you buy.

只要看看你買甜食上的標簽

Glucose, fructose, sucrose,

葡萄糖

果糖

蔗糖

maltose, lactose, dextrose, and starch

麥芽糖

乳糖

右旋糖

和澱粉

are all forms of sugar.

都是不同形態的糖類

So are high-fructose corn syrup,

果糖含量高的糖漿

fruit juice, raw sugar, and honey.

果汁

粗糖

和蜂蜜

And sugar isn't just in candies and desserts,

而且糖類不只在糖果、點心中

it's also added to tomato sauce,

它也被加到番茄醬

yogurt, dried fruit, flavored waters, or granola bars.

優格

果乾

調味水

和燕麥棒中

Since sugar is everywhere, it's important to understand

既然糖類無所不在

我們更要了解

how it affects the brain.

糖對大腦的影響

What happens when sugar hits your tongue?

當糖沾上舌頭時 會造成什麼反應呢？

And does eating a little bit of sugar make you crave more?

吃一點點糖

會不會讓你想吃更多？

You take a bite of cereal.

你吃一點麥片

The sugars it contains activate the sweet-taste receptors,

其中所含的糖

刺激了舌頭味蕾上的

part of the taste buds on the tongue.

甜味受器

These receptors send a signal up to the brain stem,

受器向大腦傳送訊號

and from there, it forks off into many areas of the forebrain,

在那訊號分支傳送到

前腦中的不同區域

one of which is the cerebral cortex.

其中一個就是大腦皮層

Different sections of the cerebral cortex process different tastes:

大腦皮層中的不同分區

處理不同味覺訊號

苦味

bitter, salty, umami,

鹹味

鮮味

and, in our case, sweet.

和我們討論的甜味

From here, the signal activates the brain's reward system.

訊號在這裡活化

大腦的報償系統

This reward system is a series of electrical and chemical pathways

這個報償系統是一系列

電子與化學的傳遞鏈

across several different regions of the brain.

橫跨大腦不同區域

It's a complicated network,

它是一個複雜的網絡

但是它可以回答一個簡單 潛意識裡的問題

but it helps answer a single, subconscious question:

should I do that again?

我要重複這個動作嗎？

That warm, fuzzy feeling you get when you taste Grandma's chocolate cake?

在品嘗奶奶巧克力蛋糕食

你這種溫暖、放鬆的感覺

That's your reward system saying,

這就是你的報償系統說：

"Mmm, yes!"

「我還要！」

And it's not just activated by food.

而且它不只可由食物啟動

Socializing, sexual behavior, and drugs

社交

性行為

和藥物

are just a few examples of things and experiences

只是其中幾件

事情或經驗

that also activate the reward system.

可以啟動報償系統的例子

但是過度活化報償系統

But overactivating this reward system kickstarts a series of unfortunate events:

會造成許多不良後果：

loss of control, craving, and increased tolerance to sugar.

失控

渴望

和對糖類耐受性增加

讓我們回到剛所講的麥片

Let's get back to our bite of cereal.

它向下進入到你的胃

It travels down into your stomach and eventually into your gut.

再到達你的腸子

And guess what?

誰料的到呢？

There are sugar receptors here, too.

腸子也有糖類受器

They are not taste buds, but they do send signals

它們不是味蕾

但也能傳送訊號

telling your brain that you're full

告訴你的腦說 你已經吃飽了

or that your body should produce more insulin

或告訴身體需要製造更多胰島素

to deal with the extra sugar you're eating.

去處理你多吃的糖

The major currency of our reward system is dopamine,

報償系統中的

主要貨幣是多巴胺

an important chemical or neurotransmitter.

它是重要的神經傳導物質

There are many dopamine receptors in the forebrain,

前腦中有很多多巴胺受體

but they're not evenly distributed.

但是分佈並不平均

Certain areas contain dense clusters of receptors,

特定地方有密集、叢聚的受體

and these dopamine hot spots are a part of our reward system.

這些是多巴胺的熱點

也是報償系統的一部份

Drugs like alcohol, nicotine, or heroin

藥物像是酒精

尼古丁

或海洛因

send dopamine into overdrive,

會造成多巴胺受體超載

leading some people to constantly seek that high,

造成一些人持續追求這種快感

in other words, to be addicted.

也就是成癮

Sugar also causes dopamine to be released, though not as violently as drugs.

糖經由一種較藥物和緩的機制

促成多巴胺的釋放

And sugar is rare among dopamine-inducing foods.

有些食物含糖量較低

Broccoli, for example, has no effect,

例如：花球甘藍就沒有作用

which probably explains

這或許可以解釋

為什麼很難叫小孩吃青菜

why it's so hard to get kids to eat their veggies.

說到健康食物

Speaking of healthy foods,

let's say you're hungry and decide to eat a balanced meal.

假設你餓了

而且決定要吃一餐

You do, and dopamine levels spike in the reward system hot spots.

你這麼做後 多巴胺量激增

刺激報償系統的熱點

But if you eat that same dish many days in a row,

但如果你一再吃同一道菜

dopamine levels will spike less and less, eventually leveling out.

多巴胺量會越來越低

最後和平常無異

That's because when it comes to food,

因為當刺激來自食物時

the brain evolved to pay special attention to new or different tastes.

大腦演化出特別的機制

關注新、或不同的味道

Why?

為什麼呢？

有兩個原因

Two reasons:

first, to detect food that's gone bad.

一、確定食物是否過期

And second, because the more variety we have in our diet,

二、因為如果我們的

飲食越多樣化

the more likely we are to get all the nutrients we need.

我們就更有可能

得到所有所需營養

To keep that variety up,

為了保持多樣性

we need to be able to recognize a new food,

我們需要辨別新食物的能力

and more importantly, we need to want to keep eating new foods.

更重要的是

我們必須想吃新食物

And that's why the dopamine levels off when a food becomes boring.

這就是為什麼食物相同時

多巴胺變化就不明顯

Now, back to that meal.

回到我們所說的那一餐

What happens if in place of the healthy, balanced dish,

如果將健康、平衡的飲食

以高糖份的食物代替

you eat sugar-rich food instead?

會發生什麼事呢？

If you rarely eat sugar or don't eat much at a time,

如果你很少吃糖

或一次吃的不多

the effect is similar to that of the balanced meal.

它的影響與均衡飲食相同

But if you eat too much, the dopamine response does not level out.

如果你吃過量

多巴胺改變並不會逐漸下降

In other words, eating lots of sugar will continue to feel rewarding.

換句話說，吃大量的糖

會繼續使人 有被回饋的感覺

In this way, sugar behaves a little bit like a drug.

這麼說來，糖就像毒品一樣

It's one reason people seem to be hooked on sugary foods.

這是為什麼有人會對

高糖食物成癮的原因

So, think back to all those different kinds of sugar.

想想各種不同的糖

Each one is unique, but every time any sugar is consumed,

每種都各有不同

但是吃進不同的糖

it kickstarts a domino effect in the brain that sparks a rewarding feeling.

都會刺激腦中的多巴胺釋放

造成被回饋的感覺

Too much, too often, and things can go into overdrive.

吃太多或太頻繁

都會造成超載

So, yes, overconsumption of sugar can have addictive effects on the brain,

所以過量攝取糖類

也會造成大腦的成癮

but a wedge of cake once in a while won't hurt you.

但是偶而吃塊蛋糕無傷大雅