Name: 頭皮屑不是不洗頭！真正兇手其實是「他」！(What Causes Dandruff?)
Uploaded: 2026-01-12T21:01:10.000Z
Duration: 5 min 40 s

It is one of the most common and annoying human experiences.

這幾乎是人類最常見、也最令人困擾的經驗之一。

You're wearing a black shirt, you look in the mirror, and

你穿著一件黑色上衣，看向鏡子，然後——

它就在那裡，像雪一樣落在你的肩膀上。

For centuries, we've tried to scrub it away.

幾個世紀以來，我們一直試著把它洗掉。

We've blamed it on bad hygiene, dry weather, or cheap shampoo.

我們怪罪它是清潔不夠、天氣乾燥，或是便宜的洗髮精。

但這裡有一個令人意外的真相：

Dandruff actually has very little to do with how often you wash your hair.

頭皮屑其實和你洗頭的頻率幾乎沒有關係。

In fact, that white flake on your shoulder is the result of a microscopic war taking place right now on top of your head.

事實上，你肩膀上的那片白色碎屑，是一場正在你頭頂上演的微觀戰爭所造成的結果。

It involves an invisible jungle, a hungry fungus, and

這場戰爭牽涉到一座看不見的叢林、一種飢餓的真菌，

a chemical reaction that half the population is allergic to.

以及一種有一半人口會過敏的化學反應。

Welcome to Simple Things: Surprising Histories.

歡迎來到《簡單的事物：驚奇的歷史》。

Today, we are looking at the biology under your hat.

今天，我們要來看看你帽子底下的生物學。

To answer the question, what actually causes dandruff?

來回答一個問題：頭皮屑究竟是怎麼產生的？

Before we meet the villain of this story, we have to clear up a massive misconception.

在我們遇見這個故事的反派之前，必須先釐清一個重大的迷思。

Most people think dandruff is just dry skin.

大多數人認為頭皮屑只是乾燥的皮膚。

皮膚剝落了，所以一定是太乾。

But biologically speaking, it's usually the exact opposite.

但從生物學角度來看，通常正好相反。

True dandruff thrives in an oily environment.

真正的頭皮屑，反而是在油性環境中茁壯成長。

That is why you rarely see dandruff on young children.

這也是為什麼你很少在幼童身上看到頭皮屑。

They haven't hit puberty yet, so their oil glands aren't fully active.

因為他們尚未進入青春期，皮脂腺還不活躍。

Here is what's happening on a cellular level.

以下是細胞層級正在發生的事情。

New cells are born at the bottom layer, and

they slowly travel to the surface to replace old ones.

然後慢慢往表層移動，取代老舊細胞。

On a healthy scalp, these old cells float away one by one.

在健康的頭皮上，這些老細胞會一個個自然脫落。

They're so small that you can't see them with the naked eye.

But with dandruff, these cells don't float away alone.

但在有頭皮屑時，這些細胞不會單獨脫落。

They stick together in clumps of hundreds, cemented by oil.

它們會被油脂黏在一起，形成上百個細胞的團塊。

When the clump gets big enough to be visible and falls off, that's the flake.

當這個團塊大到肉眼可見並掉落時，那就是你看到的頭皮屑。

So if it's not just dryness, what is causing these cells to clump and fall so frantically?

那麼，如果不是單純的乾燥，究竟是什麼讓這些細胞如此瘋狂地聚集、脫落？

To understand the cause, we have to zoom in, weigh in.

要理解原因，我們必須再放大視角，深入觀察。

你的頭皮，其實是一個生態系統。

它有地形——也就是你的皮膚。

它有茂密的植被——你的頭髮。

And it has a climate, the temperature and sweat.

而就像任何一顆行星，它也有居民。

Every human being on Earth hosts a microbiome on their scalp.

地球上每一個人，頭皮上都住著一個微生物群。

It's a mix of bacteria and fungi that live there permanently.

那是細菌與真菌的混合體，永久居住在那裡。

It sounds a little unsettling, but it's perfectly natural.

聽起來有點可怕，但這其實非常正常。

In fact, these microbes have evolved alongside us for thousands of years.

事實上，這些微生物已經和人類共同演化了數千年。

However, there is one specific resident in this scalp jungle that causes all the trouble.

不過，在這座頭皮叢林中，有一位特定的居民惹出了所有麻煩。

It's a yeast like fungus with a fancy name, Malassezia globosa.

它是一種酵母型真菌，名字很拗口，叫做球狀馬拉色菌。

Malassezia is on everyone's head right now.

馬拉色菌此刻就在每個人的頭上。

But for about 50% of the population, this fungus triggers a chain reaction that ruins the party.

但對大約 50% 的人來說，這種真菌會引發一連串反應，徹底搞砸整場派對。

真正的化學反應就在這裡發生。

The Malassezia fungus is hungry, but it's a very picky eater.

馬拉色菌很餓，但它的口味非常挑剔。

the natural oils produced by your sebaceous glands to keep your hair shiny and protected.

也就是皮脂腺分泌、用來保護頭髮並讓其有光澤的天然油脂。

The fungus feasts on these oils, but it doesn't digest everything.

這種真菌大快朵頤，但它無法完全消化。

It breaks the oil down and leaves behind a byproduct called oleic acid.

它會分解油脂，並留下名為油酸的副產物。

The fungus eats the oil and poops out oleic acid directly onto your scalp.

真菌吃掉油脂，然後把油酸直接「排泄」在你的頭皮上。

Roughly half of the people in the world are sensitive to oleic acid.

全世界大約有一半的人對油酸特別敏感。

If you're in that 50%, your body views this acid as an irritant.

如果你屬於那 50%，你的身體會把這種酸視為刺激物。

And when the human body thinks the skin is under attack, it has one main defense mechanism.

而當人體認為皮膚遭到攻擊時，它只有一個主要的防禦機制。

To get rid of the irritant, your scalp hits the accelerator.

為了清除刺激物，你的頭皮踩下了加速器。

In a normal, healthy cycle, skin cells take about a month to mature, travel to the surface,

在正常、健康的循環中，皮膚細胞大約需要一個月成熟、移動到表層，

But when your scalp is irritated by oleic acid, it speeds up this process drastically.

但當頭皮被油酸刺激時，這個過程會被大幅加快。

Instead of one month, the skin tries to turn over in just two to seven days.

從原本的一個月，縮短成只要兩到七天。

The the cells are pushed to the surface before they are fully dead or ready to separate.

細胞在還沒完全死亡、也還沒準備好分離前，就被推到表層。

They arrive in a panic, still oily and sticky, clutching onto their neighbors.

它們驚慌失措地抵達，仍然油膩又黏稠，緊抓著彼此不放。

These massive clumps of rushed cells are what you see on your collar.

這些匆忙成團的巨大細胞塊，就是你在衣領上看到的東西。

So when you use an anti-dandruff shampoo, you aren't just cleaning the hair.

所以當你使用抗屑洗髮精時，你不只是清潔頭髮。

你通常是在塗抹一種殺菌劑——

medicine designed to reduce the population of molassezia so the acid production stops and your skin can calm down.

一種用來降低馬拉色菌數量的藥物，讓油酸停止產生，頭皮得以平靜。

So the next time you see those white flakes, remember, it's not because you're dirty.

所以，下次你再看到那些白色碎屑時，請記得——那不是因為你不乾淨。

It's because you have a highly active ecosystem.

而是因為你擁有一個高度活躍的生態系統。

You have a hungry fungus, plenty of natural oil, and

一種飢餓的真菌、充足的天然油脂，

a body that is just trying a little too hard to protect you.

以及一個過度努力保護你的身體。

It's a complex biological battle happening right on top of your head.

這是一場正在你頭頂上演的複雜生物戰爭。

I hope you enjoyed this peek into the microscopic history of everyday life.

希望你喜歡這次對日常生活微觀歷史的探索。

If you learned something new, please hit that like button.

It really helps the channel and subscribe to Simple Things: Surprising Histories for more surprising stories about the world around us.

這對頻道很有幫助，也歡迎訂閱《簡單的事物：驚奇的歷史》，收看更多關於世界的驚奇故事。