What causes body odor? - Mel Rosenberg

譯者: Chen Chi-An 審譯者: Helen Chang

A pungent blend of onions, cheese, and cat urine with hints of...

混合洋蔥、起司和貓尿的 刺鼻味，還有⋯⋯

is that…wet goat?

是⋯⋯濕山羊？

Most of us don’t need more than one whiff

大部分人只需聞到一點點，

to identify that generally unpleasant, characteristic smell we call body odor.

就能辨認這一般來說 讓人不舒服又很特別的味道，

我們稱為「體味」。

But it’s a surprisingly complex phenomenon

這是很複雜的現象，

influenced by our genetic makeup, age, diet, and hygiene.

會因為基因組合、年齡、 飲食和衛生而改變。

So what is this odor, exactly?

所以體味到底是什麼？

Where does it come from?

它從哪裡來？

And can we do anything about it?

我們能做什麼？

To start, you just need two things to produce that familiar scent:

一開始，只要兩樣東西 就能製造那熟悉的氣味：

your armpit’s own secretions

腋窩的分泌物

and the bacteria that feed on them.

和依靠分泌物維生的細菌。

Most people associate body odor with sweat,

大部分人把體味和汗水 聯想在一起，

and it’s an important piece of the puzzle.

這是關鍵。

Your body has millions of sweat glands, and they come in two major types:

身體有數百萬的汗腺， 它們有兩種主要型態：

eccrine glands are found all over your skin

「外分泌汗腺」分布於全身體表，

and secrete mainly water and salt.

主要分泌「水」和「鹽」；

Apocrine glands, on the other hand, develop at puberty in your armpits

另一方面，「頂漿腺」在青春期發展，

位置在腋窩以及身體部分區域。

and a few other places on your body.

The sweat they secrete is full of proteins and fats.

頂漿腺的汗充滿 「蛋白質」和「脂肪」，

By themselves, these secretions are usually odorless.

只有這些汗是沒味道的，

That’s where bacteria come in.

而此時細菌扮演要角。

Every square centimeter of our bodies is covered with thousands of bacteria.

體表每平方公分覆蓋著成千的細菌，

Many microorganisms thrive in moist environments, like our armpits.

許多微生物需要潮濕的環境 維生，例如腋窩，

There, you can find about a million bacteria per square centimeter,

在那裡，每平方公分約有 一百萬隻細菌，

one of the highest concentrations anywhere on the skin.

這是人體表細菌 密度最高的區域之一。

Lurking in this throng of microorganisms are species of Corynebacteria,

潛伏在這群微生物中的種類有

棒狀菌屬、葡萄球菌屬、

Staphylococci,

Micrococci,

微球菌屬，及其他。

and others.

When these bacteria feed on the proteins and fats in apocrine sweat,

當這些細菌食用 頂漿腺汗液的蛋白和脂質時，

they turn the odorless compounds into new ones that can smell very unpleasant.

本來無味的化合物會被轉換， 其味道可能很不討喜。

Some of the worst offenders may be sulfur-containing chemicals;

其中最難聞的是含「硫」的化學物質，

those give body odor its oniony aroma.

它使得體味有洋蔥的氣味。

Carboxylic acids are in the mix, too, adding notes of cheese.

羧酸也在其中，增加起司的味道。

These molecules waft up from the armpit and can be sucked directly into our noses,

這些分子從腋窩飄出， 被鼻子直接吸入，

where they’re trapped and detected by an array of specialized receptors.

分子會被捕捉及偵測到， 因為有一連串特殊受器，

Those can recognize odor molecules

這些受器能辨識

濃度小於百萬分之一的氣味分子。

at concentrations of less than one in a million.

So what determines how strong your body odor might be?

是什麼因素決定體味的濃度？

It depends on the resident microbial populations in your armpit,

這取決於腋窩的微生物種類

and the nutrients that your glands provide them with.

及身體腺體提供的養分。

Your genes help determine what compounds you produce,

基因會決定製造哪種化合物

and in what quantity,

及分泌量，

so everyone has a slightly different set.

因此每個人的體味略有差異。

In fact, a gene variant that virtually eliminates body odor

事實上，因基因變異使體味減少

is common in people of East Asian descent.

在東亞人種是很常見的。

Adrenaline increases the ratio of apocrine to eccrine sweat,

腎上腺素增加頂漿腺 和外分泌汗腺的汗液比率，

so body odor can be more intense when you’re nervous.

因此當你緊張時， 體味會比較強烈。

Bacterial composition and concentration also varies between individuals

細菌組成及密度 在每個人身上不同，

and plays a part.

而這也有影響。

Even what you eat can have a small effect on how you smell.

連你吃什麼對你聞起來 都有些微的影響。

So how can we deal with body odor?

因此，我們該如何處理體味？

Washing the armpits with soap and water helps but won’t remove all the bacteria

用肥皂和水清洗腋窩有幫助， 但不能移除全部細菌，

since many are buried in deeper layers of the skin.

因為牠們多在皮膚更深層的地方。

Deodorants, however, inhibit bacterial activity and mask odors at the same time.

而除臭劑能同時 抑制細菌活動並掩蓋體味；

Antiperspirants work by forming tiny gel plugs that block sweat glands,

止汗劑藉由形成微小凝膠 塞住汗腺來達到效果，

drying out the armpits.

使得腋窩乾燥。

While we continue to battle body odor, scientists are trying to understand it.

在我們持續和體味對抗時， 科學家嘗試了解它。

We don’t know why the brain

我們不知道為何大腦

often interprets these particular odors as off-putting.

總是將此特殊氣味 解讀為令人厭惡的，

But some researchers have proposed that secretions from the armpit

但有些研究者提出假設， 說腋窩的分泌物

could have a positive function, too,

可能也有正面功能，

like cementing social bonds

如鞏固社會連結，

and providing a means of chemical communication.

以及作為提供化學通訊的方式。

We don’t know yet if that’s the case.

我們還不知道是不是如此，

For now, body odor seems to be

現在，體味似乎

just another smelly part of the human condition.

就是人體狀態中 有臭味的一部分而已。