In some cases, the results can be deadly.

某些情況下，結果可能會致死。

But what exactly is happening in the body for it to confuse nuts or shellfish with a true threat?

但究竟身體發生了什麼事，把花生或甲殼類與真正的威脅混為一談？

By definition, a reaction to a food is only considered an actual allergy if the immune system is involved.

根據定義，如果涉及免疫系統，對食物的反應僅僅認為是一般過敏。

And if the response is caused by immune cells called IgE antibodies, which we'll get more into later.

如果反應是由 IgE 抗體的免疫細胞所引起，這個我們接下來會深入討論。

But it's important to distinguish an allergy from a sensitivity or an intolerance, which

但重要的是在敏感或不耐症間區分過敏，

involve uncomfortable symptoms as a reaction to food, but don't cause an immune response.

其中一些不舒服的症狀涉及食物反應，但不會引起免疫反應。

So if you're lactose intolerant,

因此，如果你有乳糖不耐症，

you're not allergic to milk.

你並不是對牛奶過敏。

Hi. My name is Tina Sindher.

嗨，我是提娜．辛德。

I'm a Clinical Assistant Professor in allergy and immunology at Stanford University.

我是史丹佛大學過敏和免疫學的臨床助理教授。

And I see patients in my clinic with, eczema, with asthma, food allergies, with environmental allergies.

我在診所看到患有濕疹、氣喘、食物過敏和環境過敏的患者。

And my main focus lies in food allergy research.

我專攻的是食物過敏研究。

In order to understand food allergies, we need to know how the body evaluates food in the first place.

要了解食物過敏，我們需要先知道身體如何評估食物。

In a typical immune system, your body is constantly evaluating different antigens to deem them

在典型的免疫系統中，身體會不斷評估不同的抗原，

either benign or dangerous, in this case, the proteins on the food particles.

在這種情況下，食物顆粒上的蛋白質，會被判斷是良性或危險的。

When they eat a peanut for the first time, their body kind of tells your immune system,

他們第一次吃花生時，身體會告訴你的免疫系統，

like, look at this, this is a peanut, do not fight this in the future.

像是，看看這個，這是花生，以後絕不要和它打起來。

So that every time they eat a peanut, their immune system does not react to it at all.

所以他們每次吃花生時，免疫系統完全不會對花生有所反應。

The immune system is basically building up a tolerance for the next time peanuts are around.

免疫系統基本上建立了下次對花生的耐受性。

But in the allergy afflicted, by the time they eat something like a peanut, their body

但受過敏困擾的同時，當他們吃花生之類的東西，身體

is already primed for an immune response.

已經準備好進行免疫反應。

Our immune system is kind of like a seesaw, it needs balance.

免疫系統有點像蹺蹺板一樣需要平衡。

So, on one side of the seesaw is your T regulatory cells.

所以，蹺蹺板的一邊是調節性 T 細胞。

And they are kind of your brakes.

它們就像是你的煞車。

They're the cells that tell your immune system, calm down, slow down, do not fight this.

它們是一種細胞，負責告訴免疫系統，冷靜、減速，不要攻擊這個東西。

And then the Th2 is your allergic cells.

而 Th2 是你的過敏細胞。

And they are ready to go, and revved up.

它們準備好了，而且加速好了。

And they will bring in all other inflammatory cells to fight what they perceive as danger.

它們會帶入所有的發炎細胞，為了對抗它們認為危險的東西。

In most people, the T regulatory cells hold more weight in determining what's problematic and what's harmless.

在大多數人中，調節性 T 細胞在決定哪些東西有問題和無害時，扮演很重要的角色。

But in people with a more Th2-skewed system, their cells sound the alarm much more easily

但對那些 Th2 偏斜的人來說，他們的細胞更容易發出警報

and have a high sensitivity to the harmless proteins on foods, most commonly milk, eggs,

對食物上無害的蛋白質有高敏感性，最常見的是牛奶、雞蛋

wheat, soy, peanuts, tree nuts, fish, or shellfish.

小麥、大豆、花生、堅果、魚或貝類。

But having a skewed immune system isn't enough, there has to be a trigger point to

但對免疫系統偏斜的人來說是不夠的，那就必須有個觸發點

developing a specific allergy, and that's still not completely known.

來發展特定的過敏症，而這一點還不完全清楚。

One of the proposed thoughts on how allergy begins has to do with the allergen entering the body the wrong way, through the skin.

過敏症如何開始的其中一個提議，與過敏原透過皮膚以錯誤的方式進入身體有關。

Minuscule food particles floating in the air can enter the body through the skin if there

如果是由於濕疹造成皮膚屏障功能失調，

is dysfunction in the skin barrier due to something like eczema.

漂浮在空氣中的微小食物顆粒可以透過皮膚進入身體。

We're talking about nanoparticles of peanuts.

我們講的是花生的奈米顆粒。

So it can be in your bedding, it can be in the air.

可能會在你的寢具或空氣中。

You might be getting exposed to it without any knowledge of it.

你可能在不知情的情況下接觸到。

It's that it's entering our, it's interacting with our immune system in a way that it's not meant to.

它就是這樣進入我們體內，它不該與我們的免疫系統相互作用。

We're not supposed to get food allergens to come in through our skin. Or environmental.

我們不該讓食物過敏原透過皮膚、或環境因素，進入我們體內。

So really the initial process is the barrier breakdown that we're seeing.

所以真正的第一步是打破看到的障礙。

So, in some people, when immune cells in the skin encounter these antigens, they recognize

因此，在某些人中，當皮膚的免疫細胞遇到這些抗原，它們會認為

that they are foreign and in the wrong place.

抗原是不相干的人，而且還跑錯地方。

This ultimately signals the immune system to produce antibodies called immunoglobin

免疫系統產生抗體的最終信號是免疫球蛋白E

E or IgEs to fight against the food proteins.

簡稱 IgEs，來對抗食物蛋白。

Now, when this same food is finally ingested the right way through the mouth, the body's

當同樣的食物最後以正確的方式透過嘴巴吃下去，身體的

IgE's will recognize it as a threat and respond in full force, leading to an allergic reaction.

IgE 會視其為威脅並全力反應，導致出過敏反應。

And the way this looks is basically, when your mast cells and basophils open up, they

基本上看起來這樣，你的肥大細胞和嗜鹼性球打開時，它們

contain histamine and tryptase, and a bunch of other inflammatory mediators.

含有組織胺和類胰蛋白酶，還有其他發炎介質。

And those are what drives the reaction.

那些都是會引起反應的因素。

This inflammatory response mirrors the body's reaction to a parasitic infection.

這種發炎反應反映出身體對寄生蟲感染的反應。

But, skin exposure is not dangerous for those with food allergy already.

但是，皮膚暴露對已經有食物敏感的人並不危險。

Our body shouldn't be responding like that, right, to food, and that's what we're hoping

我們的身體不該像那樣對食物做出反應，而這正是我們希望弄清楚，

to figure out, and that's what we're hoping to prevent.

也是我們希望阻止的。

We know that our immune system has developed this kind of response, but we don't know the why.

我們知道免疫系統已發展出這樣的反應，但我們不清楚其中的原因。

There is a genetic component to who has allergies and who doesn't.

遺傳成分會導致小孩有沒有過敏。

Children whose parents have allergies are more likely to have allergies themselves.

父母有過敏的話，子女很可能也會過敏。

But there are other environmental factors at play that mess with the balance of the

但還有其他環境因素影響

seesaw of an individual's immune system.

個體免疫系統中蹺蹺板的平衡。

So it's not one thing, it's multifactorial.

所以，不是一種因素而已，是多重因素。

And it's our diet, it's our lifestyle, it's modern conveniences that may push us kind

我們的飲食、我們的生活方式，現代生活的便利可能讓部分人，

of over the edge for some, not all, but some.

而不是所有人佔盡優勢。

The thing is, we might just be too clean.

問題是，我們可能太乾淨了。

This is what's known as the hygiene hypothesis which says that a lack of exposure to germs

這是眾所周知的衛生假說，就是在生命早期缺乏與細菌接觸，

early in life can trigger the immune system to mistake a food protein as an invading germ.

會引起免疫系統將食物蛋白質誤以為是細菌入侵。

So for fewer allergies, maybe...

所以對於較少見的過敏反應，也許......

Get a dog, roll around in dirt, don't wash your clothes, and play in the sun.

可以養隻狗、在泥土裡滾來滾去、別洗衣服，以及在陽光下玩耍。