Flatulence and wind

What is flatulence and wind?

Flatulence and wind are symptoms related to gas in the gastrointestinal (GI) system. 'Flatulence' usually refers to gas passed per rectum. 'Wind' as a symptom may mean either belching (gas passed from the stomach outwards via the mouth - also called 'eructation') or gas passed per rectum (or even just feeling bloated).

Flatulence and belching are normal gut functions, but - culture- and context-dependent - are often seen as inappropriate, rude, or embarrassing. Excessive or distressing flatulence and belching are common symptoms.

Normal physiology

Belching¹²

This is the release of gas from the stomach, either voluntary or involuntary. It is a normal reflex which occurs most commonly after meals. Air is ingested with each swallow, though the exact amount varies. Ingested carbonated drinks also release gas in the stomach.

Excessive belching can be caused by:

• Gastric belching, where gastric air is vented. This is a normal physiological process, but some conditions may cause excessive air venting, such as gastro-oesophageal reflux disease or functional dyspepsia. Aerophagia - excessive swallowing of air into the stomach - can also cause this, although people with aerophagia tend to report abdominal bloating and distension rather than excessive belching.³

• Supragastric belching, where air is sucked into and expelled from the pharynx and oesophagus only.

Flatulence

• Intestinal bacterial colonies produce gases. Carbon dioxide, hydrogen and methane are responsible for the main volume of intestinal gas and sulfur-containing gases for malodour.

• The volume and composition of gas depends both on diet and on colonic flora.

• Abdominal bloating and flatulence are common symptoms in irritable bowel syndrome (IBS). However, colonic gas production does not appear to be increased in people with IBS; instead, visceral hypersensitivity to gut stretch seems to be implicated in these symptoms.⁴⁵

Causes of flatulence and wind (aetiology)

Belching

• Diet/lifestyle factors - eg, eating too quickly, fizzy drinks, chewing gum, smoking.

• Antacids - produce carbon dioxide gas which may contribute.

• Dyspepsia or reflux - patients may swallow air and may belch in an attempt to relieve upper GI symptoms.

• Giardiasis - can cause malodorous belching.

• Learned behaviour - supragastric belching is essentially a learned behaviour, sometimes in response to other symptoms (eg, reflux, as above).⁶

Flatulence

Symptoms may be due to excessive volume of gas or to malodour. Possible causes or contributing factors are:

• Diets high in fermentable carbohydrate (eg, pulses, bran and fruit).

• Variations in bowel flora composition.

• Constipation.

• IBS.

• Acute gastroenteritis.

• Giardiasis.

• Small intestinal bacterial overgrowth.

• Lactose intolerance.

• Malabsorption.

• Flatulence (and belching) are common in female runners. The cause is as yet unknown.⁷⁸

Assessment

• Clarify what most bothers the patient about their symptoms.

• 'Red flags' - eg, dysphagia, weight loss, rectal bleeding, persistent change in bowel habit, family history of bowel cancer.⁹

• Clinical examination (if relevant) to look for any serious signs - eg, anaemia, nodes and abdominal, pelvic or rectal masses.

Diagnosing flatulence and wind (investigations)

These depend on the clinical picture. Basic tests may be relevant to help rule out other problems (eg, as recommended in the diagnosis of IBS):¹⁰

• FBC.

• ESR or CRP.

• Antibody testing for coeliac disease.

FIT testing should be offered if there are signs or symptoms suggestive of colorectal cancer.⁹

In specialist centres, oesophageal impedance monitoring can distinguish between gastric and supragastric belching, and may be useful if there is significant diagnostic doubt.¹

Breath tests may be used to evaluate gut flora and small intestinal bacterial overgrowth.¹¹

Management of flatulence and wind

Belching

• Explanation of normal physiology and reassurance may be sufficient.

• Investigate/treat dyspepsia and reflux symptoms if relevant.

• Speech therapy or behavioural therapy may be used; these often rely heavily on breathing exercises to prevent air suction into the oesophagus and supragastric belching.⁶

• One small study of 12 patients reported improvement in belching and regurgitation symptoms from use of baclofen.¹²

Flatulence

Note that most of the research and literature on this topic relate to patients diagnosed with IBS. Possible treatments are:

• Mild physical activity - has been shown to enhance gas clearance in a study of patients with bloating.

• Treating exacerbating factors such as constipation.

• Diet:
  

  • Soluble fibre such as linseed (up to one tablespoon daily) and oats.¹⁰

  • Diets low in fermentable carbohydrate can reduce flatulence in IBS.¹³

• Probiotics:
  

  • These are 'gut-friendly' bacteria such as lactobacilli and bifidobacteria.

  • Their mechanism of action is unclear but they can alter colonic fermentation and inhibit gas-producing bacteria such as Clostridium spp. They have an effect on intestinal motility and may also have an anti-inflammatory effect on mucosal cells.

  • They have been shown to modestly reduce symptoms in patients with IBS.¹⁴

  • The specific strain of bacteria may be important but, on current evidence, it is difficult to advise which strain(s) to use.

  • Probiotics should not be prescribed within the NHS, but can be purchased by patients elsewhere.¹⁵

• Medications:
  

  • Antibiotics (eg, metronidazole or rifaximin) can be used to treat small intestinal bacterial overgrowth.¹⁶

  • Simeticone combined with loperamide may improve gas symptoms in acute diarrhoea.

  • Oral bismuth subsalicylate binds sulfide gases in the gut but is not safe for regular use due to the salicylate content.

• Supplements:
  

  • Alpha-galactosidase, an enzyme supplement, has been shown to reduce flatus after eating beans, but there is insufficient evidence to support its regular use.¹⁷

• Odour reduction devices:
  

  • Garment devices containing activated charcoal have been tested in one trial.¹⁸ This found that briefs containing charcoal were effective, but pads and cushions of the same material were less helpful.