Flatulence means expulsion of flatus or gas that passes through the digestive tract and the rectum before passing out of the anus as wind, which is commonly known as farting. Wind can also be released from the digestive tract via the oesophagus and the mouth as a burp.
Part of the gastrointestinal process for ingesting and digesting food involves excreting faeces as a by-product, which involves muscle contractions known as a peristaltic wave. Once food is chewed and swallowed the circular muscular contractions start in the oesophagus, passing the food in a ball or “bolus” through the gastrointestinal tract into the stomach. Once food and nutrients are absorbed in the body the faeces by-product is passed from the colon, through the rectum and then out by the anus. Gases originate in the body from foods we consume and the muscle action involved in consumption, digestion and defecation.
Flatus includes gases with odour and those that are odourless. The odourless gases consist primarily of Nitrogen, Hydrogen and Carbon Dioxide in different quantities, along with smaller amounts of Oxygen and, in some cases, Methane. Gases with odour contain sulphur or sulfide, such as dimethyl sulfide or hydrogen sulfide, or result from bacterial action within the rectal passage and faeces.
Flatulence results from normal, healthy digestive and bowel function. However, excessive flatulence causing abdominal swelling and pain is not healthy and can be a signal of a digestive tract disorder or disease. The quantities of gases produced for natural flatulence are not harmful or poisonous, but if abnormal it can increase bowel pressure causing ill health.
Flatulence results from two main sources. The first being the air we breathe in through the nose and mouth exogenously and swallowing too much air. The second is flatus gas produced endogenously through the peristalsis function of the digestive and bowel system, such as when digesting food or if the digestive or bowel system is dysfunctional, due to a medical condition or disease. Excessive flatulence from endogenous gases usually occurs if food is not entirely digested by the small intestine or stomach before reaching the large intestine or colon. Another cause may be from yeast fermentation in the gastrointestinal tract, or bacterial overgrowth and infection. Raised atmospheric pressure, such as climbing or flying at high altitudes, can also trigger increased flatulence.
Normally we all swallow air through the nose and mouth as we breathe, talk, drink and eat. We may swallow more air than usual when gasping for air after heavy sporting activity or while drinking excessive amounts of water after feeling dehydrated or eating salty foods. More air than normal is usually swallowed during activities, such as chewing fast, smoking, biting nails, chewing gum and sucking objects like pens.
Smelly flatulence results from the presence of sulphur or bacteria in the gastrointestinal tract – bowel and rectum – giving the gas a rotten egg or cabbage smell. Noisy flatulence occurs due to the sphincter muscle in the anus vibrating as peristalsis movement pushes the gases forward to be released by the anus. Another cause for the noise may be when the gas is trapped between closed buttock cheeks and then released with speed as the cheeks part.
The peristalsis muscle movement in the bowel enables faeces to be excreted and this peristalsis movement then causes gases to be released during a bowel movement. Muscles in the gastrointestinal and bowel system are stimulated for peristalsis movement during certain activities, such as exercise, sexual intercourse and orgasm, sneezing and coughing. The reason these muscles are stimulated is because during such activities the muscles, such as those of the rectum, are contracted and then relaxed releasing air via the anal sphincter muscle. Flatulence is also more common when gastrointestinal disorders are present.
Sources of carbohydrates, particularly polysaccharides with long carbohydrate monomer and glycosidic bonds such as cellulose, chitin, glycogen and starch, can be indigestible because of their solid state and insolubility in water. Although we need these carbohydrates to give us energy, they can be difficult to metabolise and digest. These potentially indigestible foods include beans, lentils, potatoes, oats, wheat, yeast, nuts, raisins, prunes, onions, garlic, leeks, turnips, radishes, cabbage, cauliflower, broccoli and sprouts. When such carbohydrates pass through our gastrointestinal system and are not digested, microorganisms attempt to assist digestion and food movement in the upper intestine. When this undigested food arrives in the lower intestine, bacteria intervene to aid in further digestion, which causes flatulence. Slimming products and diabetic foods often contain indigestible raffinose, lactose, fructose and sorbitol sugars and may also cause flatulence.
Burping arises when partial pressure in the blood component of the intestine is lower than the partial pressure within the intestinal lumen cavity that holds digested foods and absorbs nutrients during a digestive transition. The pressure and gas within the intestinal lumen diffuses through the intestinal wall into the blood that passes through the lungs and is then exhaled as a burp. Burping can be chronic in people with gastroesophageal reflux disease (GERD), gastroparesis or peptic ulcers.
When food is not digested in the upper intestine and moves undigested into the lower intestine, gases can build up, causing a pressure increase in the abdomen and bowel that leads to pain and bowel distension. Constipation or irregular bowel movements may occur. Although it is natural for people to pass wind knowingly and unknowingly, such as when they sleep (about fifteen to twenty times within twenty four hours), excessive flatulence may be a symptom of gastrointestinal dysfunction. It is unhealthy for people to hold gas in and not release it, because this causes pressure to build up within the bowel.
Flatulence is abnormal when excessive flatulence frequently occurs or if the flatulence has a foul odour. If the volume of gas during an episode of flatulence is very high, it is also best to seek medical advice.
Medical attention should definitely be sought if frequent excessive flatulence is accompanied by a swollen or bloated abdomen, pain, diarrhoea, constipation, blood in faeces, bowel incontinence, raised or chilling temperature, nausea, vomiting, joint and muscle pain, changes in appetite and weight loss.
Health disorders associated with flatulence may include constipation, irritable bowel syndrome, lactose-intolerance, parasitic infections, gastroenteritis infection, gluten intolerance or coeliac disease and nutritional mal-absorption. Flatulence can be a side-effect of some gastrointestinal surgeries.
After initial discussion of symptoms, diet, lifestyle and physical examination, other tests may include blood or breath tests to determine what may be the cause of intolerance and flatulence. Patients may be advised to follow a dietary regimen to rule out certain triggers. If gastrointestinal dysfunction is suspected, endoscopic and biopsy testing may be necessary.
Flatulence can be self-managed or medically treated. Self-management may involve changes in diet to avoid flatulence-causing foods and increasing fibre intake. Using spices, such as caraway, turmeric, cumin, coriander and seaweed can all stimulate healthy digestion. Ingesting probiotics in live yoghurt and dairy lactose alternatives may also help. Medical treatment for flatulence may include charcoal tablets, antacids, alpha-galactosidase digestive enzyme supplements (such as lactase), antibiotics, and bismuth subgallate (such as Beano). Medical advice should be sought for excessive flatulence to identify the cause and find appropriate treatment.