Amount and constituents
The primary constituents of flatulence (collectively known as flatus) are the non-odorous gases nitrogen (ingested), oxygen (ingested), methane (produced by anaerobic microbes), carbon dioxide (produced by aerobic microbes or ingested), and hydrogen (produced by some microbes and consumed by others). Odors result from trace amounts of other components (often sulfuric, see below).
Nitrogen is the primary gas released. While methane is popularly associated with flatulence, evidence suggests that two-thirds of all humans do not release methane at all in their flatulence. Methane and hydrogen are flammable, and so some flatulence is susceptible to catching fire. Gas released mostly has a foul odor which mainly results from butyric acid (rancid butter smell) and sulfur compounds such as hydrogen sulfide (rotten egg smell) and carbon disulfide that are the result of protein breakdown.
Aerosolized particles of feces are also present in flatus, though in minuscule amounts.
The endogenous gases are produced as a by-product of digesting certain types of food. Flatulence producing foods are typically high in complex carbohydrates (especially oligosaccharides such as inulin) and include beans, milk, onions, yams, sweet potatoes, citrus rinds, chestnuts, cashews, broccoli, cabbage, Jerusalem artichokes, oat, yeast in breads, etc.
In beans, endogenous gases seem to arise from oligosaccharides, carbohydrates that are resistant to digestion: these pass through the upper intestine largely unchanged, and when they reach the lower intestine, bacteria feed on them, producing copious amounts of gas (McGee 1984 pp.257-8).
In the case of those with lactose intolerance (i.e., most non-Caucasian humans), 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 (McGee, 1984 pp.257-8).
Mechanism of action
Flatus is brought to the anus 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.
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.
Probiotics (yogurt, kefir, acidophilus, bifidus, etc.) and prebiotics (such as FOS) may also reduce flatulence if they are used to restore balance to the normal intestinal flora; used in excess, however, they may create an imbalance which increases flatulence.
Medicinal charcoal tablets have also been reported as effective in reducing both odor and quantity of flatus when taken immediately prior to food that is likely to cause flatulence later.
For acute situations, it is recommended to spread the buttocks, so as to stretch open the sphincter while the gas is passed. This is best accomplished by sitting on one buttock, shifting body weight laterally, then putting the body weight on the other buttock. The opening will not snap shut and the passage will be silent. If done incorrectly, however, this may result in a characteristic high-pitched squeal.
If sitting on a cushioned surface, the gases can be directed into the open-cell polyurethane foam and somewhat quarantined. Following the fart, standing will not release the odor, in fact, the gases will be further pushed to the center of the cushion. The gases will not leak out and be detectable, unless the cushion is compressed again under the weight of another person. The use of this phenomenon as a practical joke is obvious.
While not affecting the production of the gases themselves, agents which lower surface tension can reduce the disagreeable sensations associated with flatulence, by aiding the dissolving of the gases into other liquid and solid fecal matter.
Activated charcoal underwear and pads can be somewhat effective at reducing the odors of flatulence, but these products do not muffle the sound. Additional security can be obtained with common deodorizers and perfumes. Care should be taken to select a perfume that combats the odor, with floral and citrus notes, instead of musk, which would complement the offending odor.
There is no particular harm to come from holding in farts. Farts are not poisonous, they are a natural component of intestinal contents. However, discomfort may develop from the buildup of gas pressure. In theory, pathological distension of the bowel, leading to constipation, could result if a person holds in farts.
It is sometimes perceived that bovine flatulence is a source of greenhouse gas and may contribute to the greenhouse effect, however only one sixth of the total greenhouse gas emissions from livestock is produced by animal flatulence; the remainder is produced by animal burping. Livestock in New Zealand are said to produce about half of New Zealand's greenhouse gas emissions. Livestock in Australia contribute approximately 14 percent of that country's greenhouse gas emissions.
People will often strain to hold in a fart when in polite company, or position themselves to conceal the noise and smell of a fart using the techniques mentioned above.
Flatulence can be considered humorous to some people, either due to the scent or the sounds produced. Some find humor in lighting farts, which is possible due to the presence of flammables, such as methane.
Literature and the arts
In Dante's Divine Comedy, the last line of Inferno Chapter XXI reads: ed elli avea del cul fatto trombetta ("and he used his ass as a trumpet"), 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 arse out a window and farts in the face of his rival Absolom. Absolom then sears Nicholas's bum with a red-hot poker. (Lines 690-707)
In James Joyce's Ulysses (novel), the main character, Leopold Bloom, breaks wind in the Sirens chapter of the book.
The Walter the Farting dog series of children's books by William Kotzwinkle and Glenn Murray feature a dog with a flatulence problem as a central comedic element.
A few individuals, such as Le Pétomane, have brought flatulence onto the stage in one-man shows.
In the cinema, farting is featured in Thunderpants, Blazing Saddles, Kangaroo Jack, Fart: The Movie, American Pie, The Nutty Professor, South Park and Austin Powers, among others.
Farting is no longer summarily censored from television broadcasts. During the telecast of Super Bowl XXXVIII in the United States, a beer advertisement featured a horse passing gas.
- Edward de Vere, Earl of Oxford 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 farts.
- In August,2005, New Scientist magazine reported
that inventors Michael Zanakis and Philip Femano had
been awarded a US patent (number 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 and UK Patent Application No. GB2289222, for "A fart collecting device," 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."