Flatulence

Flatulence
Specialty	Gastroenterology

Flatulence is the presence of a mixture of gases known as flatus in the digestive tract of mammals. Flatus is expelled under pressure through the anus, usually accompanied by a distinct odor and sound, a process known informally as farting. The non-odorous gases are mainly nitrogen (ingested), carbon dioxide (produced by aerobic microbes or ingested), and hydrogen (produced by some microbes and consumed by others), as well as lesser amounts of oxygen (ingested) and methane (produced by anaerobic microbes). Odors result from trace amounts of other components (often containing sulphur, see below).

Composition of flatus gases

Nitrogen is the primary gas released. Methane and hydrogen, lesser components, are flammable, and so flatus is susceptible to catching fire. Not all humans produce flatus that contains methane. For example, in one study of the feces of nine adults, only five of the samples contained bacteria capable of producing methane. Similar results are found in samples of gas obtained from within the rectum. The gas released during a flatus event frequently has a foul odor which mainly results from low molecular weight fatty acids such as butyric acid (rancid butter smell) and reduced sulfur compounds such as hydrogen sulfide (rotten egg smell) and carbonyl sulfide that are the result of protein breakdown. The incidence of odoriferous compounds in flatus increases from herbivores, such as cattle, to omnivores to carnivorous species, such as cats. Flatulence odor can also occur when there is a number of bacteria and/or feces in the anus while being expelled. A small amount of solid or liquid fecal matter in fine particulate aerosol form may also be expelled, and included, along with flatulence.

Causes

Intestinal gas is composed of 90% exogenous sources (air that is ingested through the nose and mouth) and 10% endogenous sources (gas produced within the digestive tract). The exogenous gases are swallowed (aerophagia) when eating or drinking or during times of excessive salivation (as might occur when nauseated or as the result of gastroesophageal reflux disease). The endogenous gases are produced as a by-product of digesting certain types of food.

In the case of those with lactose intolerance, intestinal bacteria feeding on lactose can give rise to excessive gas production when milk or lactose-containing substances have been consumed.

Interest in the causes of flatulence was spurred by high-altitude flight and the space program; the low atmospheric pressure, confined conditions, and stresses peculiar to those endeavours were cause for concern.

Mechanism of action

The noises commonly associated with flatulence are caused by the vibration of the anus. The sound varies depending on the tightness of the sphincter muscle and velocity of the gas being propelled, as well as other factors such as water and body fat. The pitch of the flatulence outburst can also be affected by the anal embouchure. Among humans, sometimes farting happens accidentally, such as incidentally to coughing or sneezing; on other occasions, intentional farting occurs through the tensing and releasing of the anal sphincter.

Flatus is brought to the rectum in the same peristalsis method as feces, causing a similar feeling of urgency and discomfort. Nerve endings in the rectum learn to distinguish between flatus and feces, although loose stool can confuse these nerves, and sometimes results in accidental defecation.

Remedies

Dietary

Certain spices counteract the production of intestinal gas, most notably cumin, caraway and the closely related ajwain, turmeric, asafoetida (hing), epazote, and kombu kelp (a Japanese seaweed). Many people report that by reducing intake of most refined carbohydrates (such as rice, pasta, potatoes and bread), the amount of flatulence may decrease significantly. The water-soluble oligosaccharides in beans that contribute to production of intestinal gas can be reduced through a regime of brief boiling followed by a long period of soaking, but at a cost of also leaching out other water-soluble nutrients. Also, gas can be reduced by fermenting the beans, and making them less gas-inducing, by cooking them in the liquor from a previous batch. Lactobacillus casei and Lactobacillus plantarum have recently been proven responsible for this effect. Some legumes also stand up to prolonged cooking, which can help break down the oligosaccharides into simple sugars. Fermentation also breaks down oligosaccharides, which is why fermented bean products such as miso and tofu are less likely to produce as much intestinal gas.

Probiotics (yogurt, kefir, etc.) often reduce flatulence when they are used to restore balance to the normal intestinal flora. Prebiotics, which generally are non-digestible oligosaccharides, such as Fructooligosaccharide, generally increase flatulence in a similar way as described for lactose intolerance.

Medicinal activated charcoal tablets have also been reported as effective in reducing both odor and quantity of flatus when taken immediately before food that is likely to cause flatulence later.

Pharmacological

Digestive enzyme supplements can significantly reduce the amount of flatulence that is caused by some components of foods not being digested by the body and feeding the microbes in the small and large intestines. It has been shown that alpha-galactosidase enzymes, which can digest complex sugars, are effective in reducing the volume and frequency of flatus. The enzymes alpha-galactosidase (brands Beano, Bean-zyme), lactase (brand Lactaid), amylase, lipase, protease, cellulase, glucoamylase, invertase, malt diastase, pectinase, and bromelain are available, either individually or in combination blends, in commercial products.

The antibiotic rifaximin, often used to treat diarrhea caused by the microorganism E. coli, has been shown to reduce both the production of intestinal gas and the frequency of flatus events.

While not affecting the production of the gases themselves, surfactants (agents which lower surface tension) can reduce the disagreeable sensations associated with flatulence, by aiding the dissolution of the gases into liquid and solid fecal matter.

Often it is helpful to ingest small quantities of acidic liquids with meals, such as lemon juice or vinegar, to stimulate the production of hydrochloric acid, which in turn increases enzyme production. This facilitates digestion and may limit gas production.

Health effects

As a normal body function, the action of flatulence is an important signal of normal bowel activity and hence is often documented by nursing staff following surgical or other treatment of patients. However, symptoms of excessive flatulence can indicate the presence of irritable bowel syndrome or some other organic disease. In particular, the sudden occurrence of excessive flatulence together with the onset of new symptoms provide reason for seeking further medical examination.

Flatulence is not poisonous; it is a natural component of various intestinal contents. However, discomfort may develop from the build-up of gas pressure. In theory, pathological distension of the bowel, leading to constipation, could result if a person holds in flatus.

Not all flatus is released from the body via the anus. When the partial pressure of any gas component of the intestinal lumen is higher than its partial pressure in the blood, that component enters into the bloodstream of the intestinal wall by the process of diffusion. As the blood passes through the lungs this gas can diffuse back out of the blood and be exhaled. If a person holds in flatus during daytime, it will often be released during sleep when the body is relaxed. Some flatus can become trapped within the feces during its compaction and will exit the body, still contained within the fecal matter, during the process of defecation.

Recording flatulence events

The term meteorism is defined as the presence of gas within the abdomen or intestines. However, it is sometimes also used to describe the condition of excessive flatulence. Since subjective judgments vary considerably about what constitutes normal and elevated levels of flatulence, medical personnel sometimes instruct a patient complaining about excessive flatulence to maintain a personal flatulence diary. Researchers studying flatulence have also developed what is called a flatulogram. Its horizontal axis represents time (typically 24 hours, with each hour being marked on the time line). The subject is instructed to make a pencil mark on this line at each point in time that they notice flatus passing through the anus. The acoustical volume of the event is indicated by the vertical distance that the pencil mark rises above the time line. Inaudible events are indicated by a short mark that extends only below the time line.

Environmental impact

Livestock are a significant contributing factor to the greenhouse effect, accounting for around 20% of global methane emissions. Less than 10% of the total greenhouse gas emissions from livestock is produced by animal flatulence; most is produced by animal burping. Livestock in New Zealand account for 60% of the country's greenhouse gas emissions. Livestock in Australia contribute approximately 14% of that country's greenhouse gas emissions .

Social context

In many cultures, excessive human flatulence is regarded as embarrassing and repulsive, even to the point of being a taboo subject. People will often strain to hold in the passing of gas when in polite company, or position themselves to conceal the noise and smell.

Flatulence is a potential source of humor, either due to the foul smell or the sounds produced. Some find humour in flatulence ignition, which is possible due to the presence of flammable gases such as hydrogen and methane, though the process can result in burn injuries to the rectum and anus.

The History of Farting, by Benjamin Bart, is a collection of assorted limericks, facts, and blurbs on farting, while Who Cut the Cheese: A Cultural History of the Fart, by Jim Dawson, gives a more complete cultural discussion of the historical and social significance of farting.

Types of Flatulence

• Rotten Egg Flatulence-Smells of rotten eggs, which is attributable to its high hydrogen sulfide content.
• Silent But Deadly (SBD)-A silent, but rather foul smelling gas.
• Machine Gun-A rapid fire succession of flatulence emitted from the anus; the sound is analogous to machine gun fire.
• Squeaker-An emittance of flatulent gas that usually accompanies a high pitched squeaking noise.

Literature and the arts

• In St. Augustine's The City of God, Augustine makes note of men who "have such command of their bowels, that they can break wind continuously at will, so as to produce the effect of singing." (The City of God Against the Pagans, ed and trans Philip Levine (Cambridge, MA: Harvard University Press, 1966), XIV.24)

• In Dante's Divine Comedy, the last line of Inferno Chapter XXI reads: ed elli avea del cul fatto trombetta ("and he made a trumpet of his buttocks"), in the last example the use of this natural body function underlined a demoniac condition.

• In Chaucer's Miller's Tale (one of the Canterbury Tales), the character Nicholas hangs his buttocks out of a window and farts in the face of his rival Absolom. Absolom then sears Nicholas's bum with a red-hot poker ("Nicholas quickly raised the window and thrust his ass far out...At this Nicholas let fly a fart with a noise as great as a clap of thunder, so that Absolom was almost overcome by the force of it. But he was ready with his hot iron and smote Nicholas in the middle of his ass."). (Lines 690–707)

• In the translated version of Penguin's 1001 Arabian Nights Tales, a story entitled "The Historic Fart" tells of a man that flees his country from the sheer embarrassment of farting at his wedding.

• Friedrich Dedekind's 16th century work, Grobianus et Grobiana, appeared in England in 1605 as The Schoole of Slovenrie: Or, Cato turnd wrong side outward, published by one "R.F.". The "Schoole" taught its students that holding back the desire to urinate, fart, and vomit was bad for one's health; thus, one has to indulge freely in all three activities.

• François Rabelais' tales of Gargantua and Pantagruel are laden with acts of flatulence. In Chapter XXVII of the second book, the giant, Pantagruel, releases a fart that "made the earth shake for twenty-nine miles around, and the foul air he blew out created more than fifty-three thousand tiny men, dwarves and creatures of weird shapes, and then he emitted a fat wet fart that turned into just as many tiny stooping women."

• Montaigne, in his essay "Of the Force of Imagination", includes a discussion of flatulence. Of "the vessels that serve to discharge the belly", he writes "I myself knew one so rude and ungoverned, as for forty years together made his master vent with one continued and unintermitted outbursting, and 'tis like will do so till he die of it".

• Benjamin Franklin, in his open letter "To the Royal Academy of *****", goes on at length in ye olde eloquent style that is his wont about flatulence. He satirically proposes that converting farts into a more agreeable form through science should be a milestone goal of the Royal Academy. http://teachingamericanhistory.org/library/index.asp?document=470

• In Mark Twain's 1601, properly named [ Date: 1601.] Conversation, as it was the Social Fireside, in the Time of the Tudors, a cupbearer at Court who's a Diarist reports:

In ye heat of ye talk it befel yt one did breake wind, yielding an exceding mightie and distresfull stink, whereat all did laugh full sore.

The Queen inquires as to the source, and receives various replies. Lady Alice says

"Good your grace, an' I had room for such a thundergust within mine ancient bowels, 'tis not in reason I coulde discharge ye same and live to thank God for yt He did choose handmaid so humble whereby to shew his power. Nay, 'tis not I yt have broughte forth this rich o'ermastering fog, this fragrant gloom, so pray you seeke ye further.".

• In Emile Zola's La Terre (the 15th volume of the series Les Rougon-Macquart), the eldest Fouan son can fart at will and keeps winning free drinks by betting on his skill.

• In James Joyce's Ulysses, the main character Leopold Bloom breaks wind in the "Sirens" chapter of the book.

• The Gas We Pass is a popular children's book in the United States about flatulence.

• In the cinema, farting has been featured in films intended for adult audiences such as Blazing Saddles. However, this caused some controversy in the United States: when it was run as a movie of the week by ABC the farting sounds were overdubbed with sounds from the surrounding horses, so the scene had cowboys sitting around a campfire standing up and leaning over for no apparent reason (Dawson, 1999, p. 125).

• The film Wet Hot American Summer features a boy lighting a fart as an act in a talent show. Additionally, the film's DVD features an optional "fart track" that adds fart noises to the film's audio.

• An episode of MythBusters featured myths about flatulence and determined the chemical composition of a typical flatus.

• "I fart in your general direction" is a popular phrase from Monty Python and the Holy Grail.

• The lighting of flatulence is a plot device in the movie, South Park: Bigger, Longer & Uncut and flatulence in general is featured prominently in many South Park episodes, noteably "Spontaneous Combustion".

• Brent Spiner's character in the movie The Master of Disguise suffered from uncontrolled flatulence any time he broke into a fit of evil laughter.

• The lighting of flatulence is used as a device of social acceptance in a dream sequence of Dumb and Dumber.

Curiosities

• According to "The Great Fart Survey" [4], 34% of those who participated like the smell of their own farts.

• Le Petomane "the Fartiste" a famous French performer in the nineteenth century as well as many professional farters before him did flatulence impressions and held shows. Mel Brooks named his fictional governor (played by himself) William J. LePetomaine in the Western spoof film Blazing Saddles.

• An apocryphal story about Edward de Vere, Earl of Oxford is that he farted while swearing loyalty to Queen Elizabeth I and consequently went into self-imposed exile for seven years. After his return, the Queen was reported to have reassured de Vere: "My Lord, I had quite forgotten the fart." (John Aubrey, Brief Lives)

• Emperor Claudius passed a law legalizing farting at banquets out of concern for people's health. There was a widespread misconception that a person could be poisoned by retaining flatus.

• In August 2005, New Scientist magazine reported that inventors Michael Zanakis and Philip Femano had been awarded a US patent (U.S. patent 6,055,910) for a "toy gas-fired missile and launcher assembly". The abstract of the patent makes it clear that this is, in fact, a fart-powered rocket:

  "A ... missile is composed of a soft head and a tail extending therefrom formed by a piston. The piston is telescoped into the barrel of a launcher having a closed end on which is mounted an electrically activated igniter, the air space between the end of the piston and the closed end of the barrel defining a combustion chamber. Joined to the barrel, and communicating with the chamber therein, is a gas intake tube having a normally closed inlet valve. To operate the assembly, the operator places the inlet tube with its valve open adjacent [to] his anal region, from which a colonic gas is discharged. The piston is then withdrawn to a degree producing a negative pressure to inhale the gas into the combustion chamber to intermix with the air therein to create a combustible mixture. The igniter is then activated to explode the mixture in the chamber and fire the missile into space."

• British inventors have also patented fart-related ideas, such as "A fart collecting device," which includes a drawing of the invention deployed and ready for action, with helpful numbers to identify the various components. "It comprises a gas-tight collecting tube 10 for insertion into the rectum of the subject. The tube 10 is connected to a gas-tight collecting bag (not shown). The end of the tube inserted into the subject is apertured and covered with a gauze filter and a gas permeable bladder 28."

• Mambo Graphics, an Australian surfwear label, features the iconic "Farting Dog" design [5] in its lineup. Here the flatulence is depicted as a musical note emanating from the dog's backside.

See also

• Professional farter
• Borborygmus
• Vaginal flatulence
• The Gas We Pass
• Fart lighting

References

Nontechnical resources

• Franklin, Benjamin (2003). Japikse, Carl (Ed.) (ed.). Fart Proudly ((Reprint) ed.). Frog Ltd/Blue Snake. ISBN 1-58394-079-0.
• Dawson, Jim (1999). Who Cut the Cheese?: A Cultural History of the Fart. Ten Speed Press. ISBN 1-58008-011-1.

External links

• The Merck Manual of Diagnosis and Therapy, Gas
• Facts on Farts
• Dictionary of Fart Slang
• The Great Fart Survey (simple statistical analysis of flatulence in youths) produced by Australian Broadcasting Corporation youth website, Rollercoaster)
• Flatulence Treatment