What is fat? - George Zaidan

什麼是脂肪？ - George Zaidan

Translator: Andrea McDonough Reviewer: Jessica Ruby

譯者: Marssi Draw 審譯者: Geoff Chen

Olive oil is 100% fat;

橄欖油是 100% 的脂肪

there's nothing else in it.

除此之外，沒有別的

Pancake mix, on the other hand,

鬆餅，相反地

is only about 11% fat.

只有大約 11% 的脂肪

And, yet, olive oil is good for you,

然而，橄欖油對你有益

and pancake mix is not.

而鬆餅則不然

Why is that?

為什麼？

As it turns out,

因為

the amount of fat we eat

我們所吃的脂肪量

doesn't impact our weight

並不會影響我們的體重

or our cholesterol

或是我們的膽固醇

or our risk of heart disease

又或是我們得到心臟病的機率

nearly as much as what kind of fat we eat.

只和我們吃進哪一種脂肪有關

But let's back up:

不過我們先回過頭來

What is fat?

什麼是脂肪？

If we were to zoom in on a salmon,

如果我們放大檢視鮭魚

which is a fatty fish,

鮭魚是一種脂肪很多的魚

past the organs,

past the tissues,

不看內臟、不看組織

不看內臟、不看組織

into the cells,

只看細胞

we would see that the stuff we call fat

我們就會看到我們稱為脂肪的東西

is actually made up of molecules called triglycerides,

其實是由一種稱為 三酸甘油酯的分子所組成

and they are not all alike.

而且它們還不見得都一樣

Here's one example.

舉個例子

Those three carbons on the left, that's glycerol.

左邊的那三顆碳，是甘油

Now, you can think of that as the backbone

你可以把它想像成支柱

that holds the rest of the molecule together.

能夠把其它的分子結合在一起

The three long chains on the right

右邊的那三條長鏈

are called fatty acids,

稱為脂肪酸

and it's subtle differences in the structures of these chains

這些鏈有些微的不同

that determine whether a fat is,

由此決定它們是什麼樣的脂肪

let's say, solid or liquid;

應該說，固體或是液體的

whether or not it goes rancid quickly;

會不會很快腐臭

and, most importantly, how good or how bad it is for you.

最重要的是，對你來說有多好或多壞？

Let's take a look at some of these differences.

讓我們看看有什麼不同

One is length.

第一，是長度

Fatty acids can be short or long.

脂肪酸可以是長的或短的

Another, more important difference

另外，最大的不同是

is the type of bond between the carbon atoms.

在碳原子之間是哪一種鍵

Some fatty acids have only single bonds.

有些脂肪酸只有單鍵

Others have both single and double bonds.

也有同時有單鍵和雙鍵的脂肪

Fatty acids with only single bonds

只有單鍵的

are called saturated,

稱為飽和的脂肪酸

and those with one or more double bonds

而有單鍵或更多雙鍵的

are called unsaturated.

則稱為不飽和脂肪酸

Now, most unsaturated fats are good for you,

大部份的不飽和脂肪酸 對你是有益的

while saturated fats are bad for you in excess.

而過多的飽和脂肪酸 對你則是有害的

For saturated fats, the story pretty much ends there

對飽和脂肪酸來說，大概就是這個樣子

but not for unsaturated fats.

但是對不飽和脂肪酸來說 卻不是這麼一回事

The double bonds in these molecules

雙鍵在這些分子中

have a kind of weird property;

有一種奇怪的特性

they're rigid.

它們很堅固

So, that means there are two ways

因此，有兩種方式可以

to arrange every double bond.

連結雙鍵

The first is like this,

第一種就像這樣

where both hydrogens are on same side

兩顆氫都在同一邊

and both carbons are on the same side.

兩顆碳也在同一邊

The second way is like this.

第二種方式像這樣

Now the hydrogens and carbons

氫和碳，在雙鍵對立的兩端

are on opposite sides of the double bond.

氫和碳，在雙鍵對立的兩端

Now, even though both of these molecules

即使這兩種分子

are made up of exactly the same building blocks,

都由同樣的東西組成

they are two completely different substances,

它們都還是會成為不同的物質

and they behave completely differently inside of us.

它們在我們的體內也會有不同的表現

The configuration on the left is called CIS,

左邊的這個結構稱為順式異構體 (CIS)

which you've probably never heard of.

你可能從來也沒聽過

The one of the right is called TRANS,

另一種在右邊的稱為反式異構體 (TRANS)

and you probably have heard of trans fats before.

你以前可能有聽過反式脂肪

They don't go rancid,

它們不會腐臭

they're more stable during deep frying,

它們在油炸時比較穩定

and they can change the texture of foods

而且它們可以改變食物的口感

in ways that other fats just can't.

這是其它種類的脂肪無法做到的

They're also terrible for your health,

而且它們也很不益健康

by far worse than saturated fat,

顯然比飽和脂肪酸要差得多

even though technically they're a type

即使嚴格說來

of unsaturated fat.

它們也是不飽和脂肪中的一種

Now, I know that seems crazy,

我知道聽起來很誇張

but your body doesn't care

但是你的身體並不在乎

what a molecule looks like on paper.

分子在紙上長的樣子

All that matters is the 3-D shape

重要的是它在三度空間的形態

where the molecule fits,

分子在哪裡結合

where it doesn't,

分子在哪裡結合

and what pathways it interferes with.

還有它所造成的影響

So, how do you know if a food

那麼，你要怎麼知道

has trans fat in it?

食物裡有沒有反式脂肪呢？

Well, the only sure way to know

嗯，唯一能夠確定的方法是

is if you see the words,

如果你在食品內容物中 看到「 部分氫化」的字眼

"partially hydrogenated" in the ingredients list.

如果你在食品內容物中 看到「 部分氫化」的字眼

Don't let nutrition labels or advertising fool you.

別讓營養標籤或廣告騙了你

The FDA allows manufacturers to claim

食品藥物管理局 (FDA) 准許製造商

that their products contain

聲稱他們的產品包含

"0" grams of trans fat

「0」克的反式脂肪

even if they actually have up to half a gram per serving.

即使事實是每份的含量超過 0.5 克

But there are no hard and fast rules

但是沒有嚴格的規定

about how small a serving can be,

限制每一份最少要是多少

and, that means, you'll have to rely on seeing those key words,

也就是說，你得依賴關鍵字

partially hydrogenated,

「部份氫化」

because that's how trans fats are made,

因為那是反式脂肪製成的方式

by partially hydrogenating unsaturated fats.

透過部份氫化製成反式脂肪

So, let's go back to our olive oil and pancake mix from before.

因此，讓我們回到先前 橄欖油和鬆餅的話題

Olive oil is 100% fat.

橄欖油是 100% 的脂肪

Pancake mix is only 11% fat.

鬆餅只有 11% 的脂肪

But olive oil is mostly unsaturated fat,

但是橄欖油幾乎都是不飽和脂肪

and it has no trans fat at all.

而且它完全不包含反式脂肪

On the other hand, more than half the fat

相反地，鬆餅中有超過一半的脂肪

in pancake mix is either saturated or trans fat.

是飽和或反式脂肪

And, so, even though olive oil has 10 times

因此，即使橄欖油的脂肪是

as much fat as pancake mix,

鬆餅的十倍

it's healthy for you,

它對你還是很健康

whereas pancake mix is not.

而鬆餅則不然

Now, I'm not trying to pick on pancake mix.

我並不是要找鬆餅的碴

There are lots of foods

有很多的食品

with this type of fat profile.

含有這種類型的脂肪

The point is this:

重點是

It's not how much fat you eat,

吃多少脂肪不重要

it's what kind of fat.

重要的是，你吃了什麼樣的脂肪

And what makes a particular fat healthy or unhealthy

還有，是脂肪的形態

is its shape.

決定它是否健康