關於屁的科學

來自專欄夏面雙語新聞

Have you ever been in a situation where passing wind is going to be hugely embarrassing and you』ve had to hold in a fart?

你有沒有為了避免尷尬的情況發生，只好把屁憋回去的經歷？

Let』s face it – we all have.

面對現實吧！我們都碰到過這樣的情況。

But the gas cant stay trapped forever, and it could even be damaging for your digestive health to prevent it from escaping.

屁是憋不住的，而且憋屁甚至可能會影響消化道健康。

The totally natural – but potentially humiliating – release is caused by gases created when your food and drink are digested, or when you swallow air.

屁是在你在食物和飲料被消化後、吸進空氣後所產生的氣體，雖然這是一件很自然的反應，但是它可能會讓人面臨尷尬。

And if the gas isnt given its usual way out it can be reabsorbed by the body, some of it can escape through the mouth, or after time it can escape as an uncontrollable fart.

如果屁不從該出來的地方排出的話，它可能會被身體吸收，有部分會從口裡排出， 或者隨後它們將自行排出。

Clare Collins, a professor in nutrition and dietetics at the University of Newcastle in New South Wales, Australia, writes for The Conversation to explain what farts are and what happens if you hold them in:

澳大利亞新南威爾士紐卡斯爾大學的營養與飲食教師克萊爾.柯林斯在「談話」網站上向人們闡述了屁是什麼以及憋屁會有什麼影響。

Flatus, farts and breaking wind refer to intestinal gases that enter the rectum due to the body』s usual gastrointestinal processes of digestion and metabolism and then leave via the anus.

屁指的是在腸胃在經過常見的消化和新陳代謝的過程後，腸道內的氣體通過直腸後被肛門排出的氣體。

As your body digests food in the small intestine, components that can』t be broken down move further along the gastrointestinal tract and eventually into the large intestine called the colon.

小腸在消化食物時，不能消化的那部分會進入胃腸道，並最終到達大腸中的直腸部分。

Intestinal bacteria break down some of the contents by fermentation.

腸道細菌會用發酵的方式分解其中一些部分。

This process produces gases and by products called fatty acids that are reabsorbed and used in metabolic pathways related to immunity and preventing disease development.

在這個分解過程中會產生一些氣體和脂肪酸等副產品。脂肪酸可以被重新吸收並用於和免疫及防止病情發展的代謝中。

Gases can either be reabsorbed through the gut wall into the circulation and eventually exhaled through the lungs or excreted via the rectum, as a fart.

氣體可被腸壁重新吸收，重新進入循環，最後通過肺部呼出，或通過直腸以放屁的形式排出。

Trying to hold it in leads to a build up of pressure and major discomfort.

憋屁導致壓力的上升，帶來嚴重不適感。

A build up of intestinal gas can trigger abdominal distension, with some gas reabsorbed into the circulation and exhaled in your breath.

腸內氣體的堆積將導致脹氣，腹中的部分氣體會將重新被吸收進入循環，經嘴巴排出。

Holding on too long means the build up of intestinal gas will eventually escape via an uncontrollable fart.

憋屁的時間過長意味著腸內氣體會自行排出。

The research is not clear on whether the rise in pressure in your rectum increases your chance of developing a condition called diverticulitis, where small pouches develop in the gut lining and become inflamed – or whether it doesn』t matter at all.

該研究尚不清楚直腸內壓力的增加是否會導致憩室炎，即腸壁中的袋狀物出現發炎的癥狀，或它對直腸沒有任何的影響。

How much farting is normal?

放多少屁是正常的？

It can be challenging for researchers to get people to sign up for experiments that measure farts.

研究人員在徵集屁的測試實驗人員時遇到了挑戰。

But thankfully, 10 healthy adults volunteered to have the amount of gas they passed over a day quantified.

但是，謝天謝地，有10個健康的成人自願參與該項評估一天內排氣量的實驗。

In a 24-hour period all the flatus they expelled was collected via a rectal catheter.

他們在一天中排出的氣體被收集進了直腸導管內。

They ate normally but to ensure a boost in gas production they also had to eat 200 grams – or half a large can – of baked beans.

他們正常進食，但是為了增加排氣量，他們也要吃200克（合半罐的）烘豆。

The participants produced a median total volume of 705ml of gas in 24 hours, but it ranged from 476ml to 1,490ml per person.

參與者在24小時總共排出了705毫升的氣體，但是每個人的排氣量在476-1490毫升之間。

Hydrogen gas was produced in the greatest volume (361ml over 24 hours), followed by carbon dioxide (68ml/24 hr).

氫氣的排出量是最大的（24小時內361毫升），其次是二氧化碳（24小時內68毫升）。

Only three adults produced methane, which ranged from 3ml/24 to 120ml/24 hr. The remaining gases, thought to mostly be nitrogen, contributed about 213ml/24 hr.

只有三個成人排出了甲烷，甲烷的排出量為3-120毫升不等。其餘的氣體據稱大部分是氮氣，排出量為213毫升。

Men and women produced about the same amount of gas and averaged eight flatus episodes (individual or a series of farts) over 24 hours.

男人和女人在24小時內排氣量是相等的，平均為八個屁（個人或是一系列的屁）。

The volume varied between 33 and 125 ml per fart, with bigger amounts of intestinal gas released in the hour after meals.

每次放屁排出的氣體量為33-125毫升不等，餐後排氣量更大。

Gas was also produced while they were asleep, but at half the rate compared to during the day (median 16ml/hr vs 34ml/hr).

人們在睡覺的時候也會排出氣體，但是比白天的少一半，晚上每小時排氣量為16毫升，而白天為34毫升。

Does more fibre produce more gas?

纖維產氣量更大？

In a study on dietary fibre and flatus, researchers investigated what happens to intestinal gas production when you put people on a high-fibre diet.

在一項有關膳食纖維和屁的研究中，研究人員調查了人們在吃高纖維食品時出現的排氣情況。

The researchers got 10 healthy adult volunteers to eat their usual diet for seven days while consuming 30 grams of psyllium – a source of fibre from plant seeds – a day as a source of soluble fibre, or not.

研究人員徵集了10健康成人志願者，他們在保持平時習慣的同時還每天吃30克的車前草，作為可溶纖維，或其他原因。車前草是一種植物種子纖維。

In the psyllium week, they were asked to add 10 grams – about one heaped tablespoon – to each meal.

在吃車前草的一周中，他們被要求在每餐時吃10克，也就是滿滿的一勺。

At the end of each week, the participants were brought into the lab and, in a carefully controlled experiment, had an intra-rectal catheter inserted to quantify how gas moved through the intestine over a couple of hours.

在這周結尾的時，參與者被帶到了實驗室中，在一個控制實驗中，他們體內被植入了直腸導管，以核實在隨後幾個小時的排氣量。

They found the high-psyllium-fibre diet led to longer initial retention of gas, but the volume stayed the same, meaning fewer but bigger farts.

他們發現，高車前草纖維飲食讓氣體在最初停留的時間更長，但是排氣量還是一樣多，這意味著屁會更少，但是「更大」。

Where do the gases come from?

氣體從何而來？

Gas in the intestines comes from different sources. It can be from swallowing air.

腸道中的氣體來自不同的地方。它可以是由吸入的氣體所產生。

Or from carbon dioxide produced when stomach acid mixes with bicarbonate in the small intestine.

或來自於胃酸和小腸中碳酸氫鹽的結合所產生的二氧化碳。

Or gases can be produced by bacteria that are located in the large intestine.

或者是大腸中細菌所產生的氣體。

While these gases are thought to perform specific tasks which impact on health, producing excessive intestinal gas can cause bloating, pain, borborygmus (which means rumbling sounds), belching and lots of farts.

這些氣體被認為是擁有對我們健康有著多重影響，產氣過多可以引起腫脹、疼痛、腸鳴、噯氣和讓人們放很多的屁。

The smelliest farts are due to sulphur containing gases.

最丑臭的屁是含硫的屁。

This was confirmed in a study of 16 healthy adults who were fed pinto beans and lactulose, a non-absorbable carbohydrate that gets fermented in the colon.

這是由16健康成人參與的研究所證實的，他們吃了斑豆、乳果糖，乳果糖是一種不可吸收的碳水化合物，它會在直腸中發酵。

The odour intensity of flatus samples was evaluated by two judges.

兩位裁判評估了屁的氣味強度。

The good news was that in a follow-up experiment, the researchers identified that a charcoal-lined cushion was able to help quash the smell of the sulphur gases.

好的消息是，在後續試驗中，研究人員鑒別除了一種木炭墊可讓硫的氣味變小。

Finally, some bad news for jet-setters: pressurised cabins on aeroplanes mean you』re more likely to pass flatus due to the gas volume expanding at the lower cabin pressure, compared to being on the ground.

最後，壞的消息是，對於經常乘坐噴氣飛機旅行的人來說，因為艙內的壓力低，氣體會擴張的緣故，你放的屁會比在地面時更多。

With modern noise-reduction features, your fellow passengers are more likely than they used to be to hear you fart.

在現代的噪音消減技術面前，你旁邊的人聽到你放屁的可能性會比以往更大。

The next time you feel a large volume of intestinal gas getting ready to do what it does, try to move to a more convenient location.

下次要排出大量氣體的時，你可以嘗試找一個更加方便的地點。

Whether you make it there or not, the best thing for your digestive health is to just let it go.

不管你有沒有到目的地，對於消化道健康來說，最好還是讓屁順其自然的排出來的好。

source：https://www.dailymail.co.uk/health/article-6150665/What-happens-hold-fart-Gas-leak-uncontrollably-come-MOUTH.html