Richard Weller: Could the sun be good for your heart?

Translator: Morton Bast Reviewer: Thu-Huong Ha

譯者: herman fu 審譯者: Jephian Lin

So, before I became a dermatologist,

在我開始做皮膚科醫生之前，

I started in general medicine,

我是從內科做起的，

as most dermatologists do in Britain.

跟英國大部分皮膚科醫生一樣，都是內科出身。

At the end of that time, I went off to Australia,

當在內科做得差不多的時候，我越洋到了澳洲，

about 20 years ago.

那時大概是 20 年前左右。

What you learn when you go to Australia

你去到澳洲就會發現

is the Australians are very competitive.

澳洲人愛好競爭。

And they are not magnanimous in victory.

對勝利絕對是當仁不讓的。

And that happened a lot:

而這種情況經常發生：

"You pommies, you can't play cricket, rugby."

「你們這班英國佬，玩木球、欖球（rugby）都不行。」

I could accept that.

這點我倒能接受的。

But moving into work --

但說到工作──

and we have each week what's called a journal club,

我們每週都有所謂的期刊例會，

when you'd sit down with the other doctors

就是當你和其他醫生相約坐下，

and you'd study a scientific paper

一起研究有關醫學的

in relation to medicine.

科學論文。

And after week one, it was about cardiovascular mortality,

而過了第一週，主題就去到有關心血管疾病的死亡率，

a dry subject -- how many people die of heart disease,

是個沉悶的主題──有多少人死於心臟疾病，

what the rates are.

死亡率是多少。

And they were competitive about this:

而他們對此也是愛競爭：

"You pommies, your rates of heart disease are shocking."

「你們這班英國佬，心臟疾病的死亡率嚇死人了。」

And of course, they were right.

而當然，他們沒錯的。

Australians have about a third less heart disease than we do --

澳洲人得心臟疾病的人比我們少三分一左右──

less deaths from heart attacks, heart failure, less strokes --

少些心臟病發、心衰竭的死亡個案，少些中風個案──

they're generally a healthier bunch.

整體而言，他們是較健康的一群。

And of course they said this was because of

而當然他們會說這歸因於

their fine moral standing, their exercise,

他們的道德修養、及運動的習慣，

because they're Australians and we're weedy pommies, and so on.

因為他們是澳洲人，我們是死英國佬，之類吧。

But it's not just Australia that has better health than Britain.

不過，不單只是澳洲整體比英國健康。

Within Britain, there is a gradient of health --

在英國之內，健康狀況也有差異──

and this is what's called standardized mortality,

而這就是所謂標準化死亡率，

basically your chances of dying.

基本上就是你有多少成機會會死。

This is looking at data from the paper about 20 years ago,

這是大約 20 年前期刊上找到的資料

but it's true today.

但今日依然適用。

Comparing your rates of dying 50 degrees north --

對比各地的死亡機率，這是北緯 50 度

that's the South, that's London and places --

也就是南方南方，倫敦一帶

by latitude, and 55 degrees --

而北緯 55 度……

the bad news is that's here, Glasgow.

壞消息是，那就是這裏，格拉斯哥。

I'm from Edinburgh. Worse news, that's even Edinburgh.

我來自愛丁堡。更壞的消息是，愛丁堡更在那方。

(Laughter)

（眾笑）

So what accounts for this horrible space here

要解釋中間這段駭人的差距：

between us up here in southern Scotland

對比在上方南蘇格蘭的我們

and the South?

以及南方土地，理由是甚麼？

Now, we know about smoking,

現在，我們都知道吸煙、

deep-fried Mars bars, chips -- the Glasgow diet.

脆炸巧克力棒（Mars bars）、炸薯條──格拉斯哥的飲食方式。

All of these things.

這些事情。

But this graph is after taking into account

但圖表經過排除

all of these known risk factors.

這些已知的高風險因素的影響。

This is after accounting for smoking, social class, diet,

這是經過排除吸煙、社會階級、飲食習慣，

all those other known risk factors.

一切其他已知的高風險因素得出來的。

We are left with this missing space

這段不見的差距，就成了一個謎：

of increased deaths the further north you go.

愈往北走，死亡數字愈高。

Now, sunlight, of course, comes into this.

這時，日光，當然浮出水面了。

And vitamin D has had a great deal of press,

維他命 D 經過廣泛報導後，

and a lot of people get concerned about it.

很多人都很關注。如是得出：

And we need vitamin D. It's now a requirement that children have a certain amount.

我們需要維他命 D。 因此飲食指引列明： 兒童須要攝取指定份量。

My grandmother grew up in Glasgow,

我祖母在格拉斯哥長大，

back in the 1920s and '30s when rickets was a real problem

早在 1920 至 30 年代，佝僂病風行，疾病嚴重，

and cod liver oil was brought in.

於是就引入魚肝油。

And that really prevented the rickets that used to be common in this city.

而這確實預防了城市中許多佝僂病案例。

And I as a child was fed cod liver oil by my grandmother.

我小時候也是被祖母餵食魚肝油的。

I distinctly -- nobody forgets cod liver oil.

我敢說──沒人會忘記魚肝油的。

But an association: The higher people's blood levels of vitamin D are,

但基於一種聯想：人血液中的維他命 D 水平愈高，

the less heart disease they have, the less cancer.

人們就少些有心臟病，少些癌症。

There seems to be a lot of data suggesting that vitamin D is very good for you.

很多資料似乎都說明維他命 D 對身體很好。

And it is, to prevent rickets and so on.

而確實是：可以預防佝僂病，等等。

But if you give people vitamin D supplements,

但如果人們服食維他命 D 補充劑，

you don't change that high rate of heart disease.

似乎並不能減少心臟病的高患病率。

And the evidence for it preventing cancers is not yet great.

而且維他命 D 補充劑並未有太大實證支持能預防癌症。

So what I'm going to suggest is that vitamin D is not the only story in town.

我想指出的是，維他命 D 並非這個城市中 關於疾病預防的全部。

It's not the only reason preventing heart disease.

維他命 D 並非預防心臟病的惟一原因。

High vitamin D levels, I think, are a marker for sunlight exposure,

我認為，高維他命 D 水平，倒標誌了較多的陽光曝曬，

and sunlight exposure, in methods I'm going to show,

而透過以下方式，我想說明，

is good for heart disease.

陽光曝曬，其實有助預防心臟病。

Anyway, I came back from Australia,

說回那個故事，我從澳洲回來之後，

and despite the obvious risks to my health, I moved to Aberdeen.

儘管身體健康暴露高風險，我搬到亞伯丁。

(Laughter)

（眾笑）

Now, in Aberdeen, I started my dermatology training.

現在，在亞伯丁，我開始了我的皮膚專科訓練。

But I also became interested in research,

但我同時對研究產生興趣，

and in particular I became interested in this substance, nitric oxide.

尤其是我有興趣研究這種物質，一氧化氮。

Now these three guys up here,

圖中這三位，

Furchgott, Ignarro and Murad,

佛契哥德、伊格那羅和慕拉德，

won the Nobel Prize for medicine back in 1998.

共同奪得了 1998 年的諾貝爾醫學獎。

And they were the first people to describe

他們同時是第一批人，能夠描述

this new chemical transmitter, nitric oxide.

這種新的化學傳導物質，一氧化氮。

What nitric oxide does is it dilates blood vessels,

一氧化氮可以擴張血管，

so it lowers your blood pressure.

從而降低血壓。

It also dilates the coronary arteries, so it stops angina.

它同時擴張冠狀動脈，停止心絞痛。

And what was remarkable about it

而最特別的一點就是，

was in the past when we think of chemical messengers within the body,

以前當我們思索身體內有甚麼化學信使時，

we thought of complicated things like estrogen and insulin,

我們總想到複雜的雌激素和胰島素，

or nerve transmission.

或者是神經傳導。

Very complex processes with very complex chemicals

很複雜的過程，牽涉很複雜的化學物質，

that fit into very complex receptors.

發生在很複雜的化學受體上。

And here's this incredibly simple molecule,

而這就是個異常簡單的分子，

a nitrogen and an oxygen that are stuck together,

將一氧一氧結合起來，

and yet these are hugely important for [unclear] our low blood pressure,

然而卻扮演重要角色，去引起血管擴張，增加血流量，

for neurotransmission, for many, many things,

作神經傳導，很多很多的功用，

but particularly cardiovascular health.

但尤其是心血管健康。

And I started doing research, and we found, very excitingly,

之後我開始研究，並得出很令人振奮的發現，

that the skin produces nitric oxide.

就是皮膚能夠產生一氧化氮。

So it's not just in the cardiovascular system it arises.

所以一氧化氮不單只在心血管系統中生成。

It arises in the skin.

一氧化氮也在皮膚中生成。

Well, having found that and published that,

之後，在得出這發現並發表後，

I thought, well, what's it doing?

我想，好了，它究竟扮演甚麼角色？

How do you have low blood pressure in your skin?

你的皮膚怎樣維持低的血壓？

It's not the heart. What do you do?

這不是心臟。可以怎麼做？

So I went off to the States, as many people do if they're going to do research,

所以我走了一趟美國，就像做研究的人都會這樣做，

and I spent a few years in Pittsburgh. This is Pittsburgh.

而我在匹茲堡待了幾年。這就是匹茲堡。

And I was interested in these really complex systems.

我對這些很複雜的系統很感興趣。

We thought that maybe nitric oxide affected cell death,

我們想，或許一氧化氮能夠左右細胞的死亡，

and how cells survive, and their resistance to other things.

細胞怎樣維持生存，以及對外來物質的抵抗。

And I first off started work in cell culture, growing cells,

我首先從細胞培植入手，就是培養細胞，

and then I was using knockout mouse models --

之後我就用了關鍵的老鼠實驗模型──

mice that couldn't make the gene.

一些無法製造某基因的老鼠。

We worked out a mechanism, which -- NO was helping cells survive.

我們得出一個運作原理，就是── 一氧化氮幫助細胞生存。

And I then moved back to Edinburgh.

之後我搬回愛丁堡。

And in Edinburgh, the experimental animal we use is the medical student.

而在愛丁堡，實驗對象就變成了醫科學生。

It's a species close to human,

是個很接近人類的物種，對吧，

with several advantages over mice:

比起老鼠有多個好處：

They're free, you don't shave them, they feed themselves,

他們是免費的，你不用替他們刮鬍鬚，照顧他們三餐，

and nobody pickets your office saying,

而沒有人會衝進你的辦公室，說：

"Save the lab medical student."

「保護實驗醫科學生的權益。」

So they're really an ideal model.

所以他們是十分理想的實驗模型。

But what we found

但我們得出的結果是

was that we couldn't reproduce in man the data we had shown in mice.

我們不能在人身上重複老鼠的實驗，並得出相同的結果。

It seemed we couldn't turn off the production

我們似乎並不能關掉

of nitric oxide in the skin of humans.

人類皮膚上產生一氧化氮的過程。

We put on creams that blocked the enzyme that made it,

我們試過塗上一層膏，阻擋催化製造一氧化氮的酶，

we injected things. We couldn't turn off the nitric oxide.

我們試過注射化學物質， 但就是不能關掉一氧化氮的製造。

And the reason for this, it turned out, after two or three years' work,

而箇中原因，經過兩三年的研究工作之後，發覺

was that in the skin we have huge stores

原來是皮膚中有大量的貯存，

not of nitric oxide, because nitric oxide is a gas,

不是一氧化氮，因為一氧化氮本體是氣體，

and it's released -- (Poof!) -- and in a few seconds it's away,

一釋放就會─(呼！) ─數秒間就消失無蹤，

but it can be turned into these forms of nitric oxide --

但是可以變成這些形式的一氧化氮──

nitrate, NO3; nitrite, NO2; nitrosothiols.

硝酸鹽 NO3 ^-；亞硝酸鹽 NO2 ^-；亞硝基硫醇。

And these are more stable,

而這些是較穩定的形態，

and your skin has got really large stores of NO.

而皮膚中確實有很大的一氧化氮貯存。

And we then thought to ourselves, with those big stores,

我們跟着就想，有了這一大堆貯存，

I wonder if sunlight might activate those stores

究竟日光能否活化這些貯存

and release them from the skin,

讓它們從皮膚中釋放，

where the stores are about 10 times as big as what's in the circulation.

因為貯存量是在血液循環中的約十倍之多。

Could the sun activate those stores into the circulation,

太陽可否將貯存中的一氧化氮釋放到血液中，

and there in the circulation do its good things for your cardiovascular system?

進而在血液循環中有助於心血管系統健康？

Well, I'm an experimental dermatologist,

對了，我是個實驗皮膚學家，

so what we did was we thought

所以我們當時接着想的是

we'd have to expose our experimental animals to sunlight.

我們會將實驗對象放於陽光中曝曬。

And so what we did was we took a bunch of volunteers

所以我們當時做的是，我們將一班自願者

and we exposed them to ultraviolet light.

放在紫外光燈的曝曬下。

So these are kind of sunlamps.

那是其中一種太陽光燈。

Now, what we were careful to do was,

此時，我們小心翼翼去做的是，

vitamin D is made by ultraviolet B rays

維他命 D 是由紫外光 B 光線造成的，

and we wanted to separate our story from the vitamin D story.

而我們想將避開維他命 D 的影響。

So we used ultraviolet A, which doesn't make vitamin D.

所以我們用了紫外光燈 A，是不會產生維他命 D 的。

When we put people under a lamp

當我們將人們放於燈下，

for the equivalent of about 30 minutes of sunshine in summer in Edinburgh,

相當於在愛丁堡夏天 曝曬日光三十分鐘的時間，

what we produced was, we produced a rise

我們得出的是，我們得出一個

in circulating nitric oxide.

一氧化氮在血液循環中提升的結果。

So we put patients with these subjects under the UV,

所以我們將一些有此方面問題的病人 放在紫外光燈下，

and their NO levels do go up,

而他們的一氧化氮含量確實提升了，

and their blood pressure goes down.

而血壓就下降。

Not by much, as an individual level,

效果不是太明顯，在個人層面之言，

but enough at a population level

但在一個社群層面，已相當有效果，

to shift the rates of heart disease in a whole population.

將整個社群中的心臟病患率往下調。

And when we shone UV at them,

而當我們只是將紫外光往他們照一照，

or when we warmed them up to the same level as the lamps,

或當我們將他們 像是照燈一樣暖起來，

but didn't actually let the rays hit the skin, this didn't happen.

但不讓光線實際的照進皮膚上，得不出這種效果。

So this seems to be a feature of ultraviolet rays hitting the skin.

所以這似乎是紫外光線接觸皮膚後的效果。

Now, we're still collecting data.

現在，我們仍在蒐集數據。

A few good things here:

已得出的好處有幾點：

This appeared to be more marked in older people.

似乎是較年長的人身上，效果較明顯。

I'm not sure exactly how much.

我不確定較明顯多少。

One of the subjects here was my mother-in-law,

其中一位試驗者是我的岳母，

and clearly I do not know her age.

很明顯我不知道她的確實年齡。

But certainly in people older than my wife,

但肯定的是，在一些比我妻子年長的人身上，

this appears to be a more marked effect.

似乎有較明顯的效果。

And the other thing I should mention

而值得一提的是

was there was no change in vitamin D.

維他命 D 含量並沒有改變。

This is separate from vitamin D.

這是與維他命 D 分開的。

So vitamin D is good for you -- it stops rickets,

所以，維他命 D 對身體有好處──它停止佝僂病，

it prevents calcium metabolism, important stuff.

預防鈣之代謝，此等重要的事。

But this is a separate mechanism from vitamin D.

但這是個與維他命 D 分開的機制。

Now, one of the problems with looking at blood pressure

好了，純粹看血壓控制其中一個弊處是

is your body does everything it can

你的身體會竭其所能

to keep your blood pressure at the same place.

去維持你的血壓在一個相當的水平。

If your leg is chopped off and you lose blood,

若你的腿不幸被砍掉，大量失血，

your body will clamp down, increase the heart rate,

你的身體會降低效能，增加心跳，

do everything it can to keep your blood pressure up.

竭其所能去維持血壓。

That is an absolutely fundamental physiological principle.

那實是很基本的生理調節原則。

So what we've next done

所以我們之後所做的

is we've moved on to looking at blood vessel dilatation.

是轉往觀察血管擴張。

So we've measured -- this is again,

如是我們測量了──再一次地，

notice no tail and hairless, this is a medical student.

沒有尾巴，沒有毛髮，這位是醫科學生。

In the arm, you can measure blood flow in the arm

在手臂，你可以測量一下手臂的血液流量，

by how much it swells up as some blood flows into it.

由手腫起的程度來判斷血流量。

And what we've shown is that doing a sham irradiation --

而我們發現的是，在未照光組

this is the thick line here --

（就是這條實心線）

this is shining UV on the arm so it warms up

這是在手臂上照紫外光，讓手臂暖起來，

but keeping it covered so the rays don't hit the skin.

但將手臂覆蓋着，不讓光線直接照射皮膚。

There is no change in blood flow, in dilatation of the blood vessels.

血液流量沒有因為血管擴張而改變。

But the active irradiation,

但在照光組中，

during the UV and for an hour after it,

在紫外光下照了一小時，

there is dilation of the blood vessels.

血管出現擴張的現象。

This is the mechanism by which you lower blood pressure,

這是身體降低血壓的運作方式，

by which you dilate the coronary arteries also,

一併會擴張冠狀動脈，

to let the blood be supplied with the heart.

增加供應心臟的血流量。

So here, further data that ultraviolet -- that's sunlight --

這裏，就是進一步支持紫外光──也就是日光──

has benefits on the blood flow and the cardiovascular system.

對血液流動以及 心血管系統有幫助的數據。

So we thought we'd just kind of model --

我們想我們的結論模型大概是──

Different amounts of UV hit different parts of the Earth at different times of year,

不同強度的紫外光， 每年在不同時節， 照射地球上不同的地方。

so you can actually work out those stores of nitric oxide --

所以你實在猜得到 被貯存的一氧化氮──

the nitrates, nitrites, nitrosothiols in the skin --

皮膚內的硝酸鹽、亞硝酸鹽、亞硝基硫醇──

cleave to release NO.

破出轉而釋放一氧化氮。

Different wavelengths of light have different activities of doing that.

不同波長的光，對這些活動有不同效果。

So you can look at the wavelengths of light that do that.

所以你可以看看 可以達到效果的波長。

And you can look -- So, if you live on the equator, the sun comes straight overhead,

而你可以看看──這樣看， 若你在赤道附近，太陽直照頭頂，

it comes through a very thin bit of atmosphere.

陽光透過很薄的大氣層射進來。

In winter or summer, it's the same amount of light.

在冬天或夏天，都有相同強度的光源。

If you live up here, in summer

若你住在北方的這裡，在夏天，

the sun is coming fairly directly down,

陽光能頗直接的到達，

but in winter it's coming through a huge amount of atmosphere,

但在冬天，陽光就要穿透好一層大氣層，

and much of the ultraviolet is weeded out,

當中好一部分紫外線經已被磨滅，

and the range of wavelengths that hit the Earth

而光線到達地球時，波長的範圍

are different from summer to winter.

從夏天到冬天都有所不同。

So what you can do is you can multiply those data

所以你可以做到的是，你將那些數據

by the NO that's released

與釋放出來的一氧化氮相乘，

and you can calculate how much nitric oxide

而你就可以計算出有多少一氧化氮

would be released from the skin into the circulation.

會從皮膚中釋放到血液循環。

Now, if you're on the equator here --

好了，若你在赤道這裏──

that's these two lines here, the red line and the purple line --

這裏有兩條線，紅線和紫線──

the amount of nitric oxide that's released is the area under the curve,

一氧化氮釋出的量，就是曲線下的部份，

it's the area in this space here.

就是這個區域的面積。

So if you're on the equator, December or June,

所以，若你身處赤道上，不論十二月還是六月，

you've got masses of NO being released from the skin.

你都有一大份量的一氧化氮，從皮膚中釋放。

So Ventura is in southern California.

另外，文圖拉就在南加利福尼亞州。

In summer, you might as well be at the equator.

在夏天，情況與身處赤道倒也差不多。

It's great. Lots of NO is released.

很不錯。很多一氧化氮會釋放。

Ventura mid-winter, well, there's still a decent amount.

在文圖拉仲冬，都算是仍有一定份量的。

Edinburgh in summer, the area beneath the curve is pretty good,

夏天的愛丁堡，曲線下的面積也不錯的，

but Edinburgh in winter, the amount of NO that can be released

但冬天的愛丁堡．可以釋放出來的一氧化氮

is next to nothing, tiny amounts.

就近乎零，只是微小份量。

So what do we think?

那我們認為怎樣？

We're still working at this story,

我們仍在這方面努力，

we're still developing it, we're still expanding it.

我們仍在發展它，我們仍在拓展這想法。

We think it's very important.

我們覺得這件事非常重要。

We think it probably accounts for a lot of the north-south health divide within Britain,

我們認為它也許能解釋 在英國之中，許多南北健康差異的理由，

It's of relevance to us.

它對我們的意義重大。

We think that the skin --

我們認為皮膚……

well, we know that the skin has got very large stores

我們確實知道 皮膚有很多一氧化氮的貯存，

of nitric oxide as these various other forms.

只是以眾多其他形式來貯存。

We suspect a lot of these come from diet,

我們猜想很多是來自飲食，

green leafy vegetables, beetroot, lettuce

綠葉蔬菜、甜菜、生菜中

has a lot of these nitric oxides that we think go to the skin.

有很多這些一氧化氮，我們認為會跑到皮膚去。

We think they're then stored in the skin,

我們想，之後它們就貯存在皮膚中，

and we think the sunlight releases this

而我們想，在日光下，它得以釋放，

where it has generally beneficial effects.

同時有助於整體身體健康。

And this is ongoing work, but dermatologists --

而這仍在研究中，但是皮膚學家……

I mean, I'm a dermatologist.

我的意思是，我是個皮膚專科醫生。

My day job is saying to people, "You've got skin cancer,

我白天的工作就是對人們說：「你有皮膚癌，

it's caused by sunlight, don't go in the sun."

是由太陽光造成的，不要走到陽光下。」

I actually think a far more important message

我其實想，有個更加重要的訊息

is that there are benefits as well as risks to sunlight.

就是太陽光有利也有弊。

Yes, sunlight is the major alterable risk factor for skin cancer,

沒錯，陽光是罹患皮膚癌， 一個可以控制的高風險因素，

but deaths from heart disease are a hundred times higher

但心臟病的死亡個案 比起皮膚癌

than deaths from skin cancer.

高出一百倍。

And I think that we need to be more aware of,

而我認為我們應該更加認清事實，

and we need to find the risk-benefit ratio.

並需要找尋 風險與益處適當的比例。

How much sunlight is safe,

陽光有多大的情況下是安全的，

and how can we finesse this best for our general health?

而我們又能怎樣巧用陽光 達到我們普遍的健康？

So, thank you very much indeed.

最後，萬分感謝在座各位。

(Applause)

（掌聲）