Burping and farting are two of the last taboos in polite Western company. Some people cheer them ("better out than in"). Most of us apologise, clench, or leave the room. Very few articles look at what the research actually says about both exits, why each happens, what each tells you about your gut, and what it costs to fight them.
This one does. Every claim below is graded:
- Strong — meta-analysis, or controlled human studies replicated by independent groups
- Moderate — smaller controlled human studies, often from one group, with consistent physiology
- Weak — plausible mechanism, little direct human data
- Myth — popular claim the evidence doesn't support
What's normal
Most people who think they pass too much wind are within the normal range. Grade: Moderate — two small, careful studies.
In a Minneapolis study, 25 healthy adults logged every passage for a week on their usual diet. They averaged about 10 a day, and the upper limit of normal was 20 (Furne & Levitt, 1996). Adding 10 g a day of lactulose, a fermentable sugar, roughly doubled that to 19.
Age, sex and whether someone produced methane made no difference to frequency. Some people simply produced more gas from the same food, because their gut bacteria did.
In Sheffield, researchers collected 24 hours of flatus through a rectal catheter from 10 volunteers (Tomlin et al., 1991). Their diet included 200 g of baked beans. Daily volume ranged from 476 to 1,491 ml, with a median of 705 ml. Men and women produced similar amounts. Output rose after meals and dropped, but didn't stop, during sleep.
| Measure | Normal range | Source |
|---|---|---|
| Passages per day | About 10 (upper limit 20) | Furne & Levitt, 1996 |
| Volume per day | 476–1,491 ml (median 705 ml) | Tomlin et al., 1991 |
| Volume on a fibre-free diet | Median 214 ml | Tomlin et al., 1991 |
Belching has no equivalent reference count. Gastric belches are a normal venting reflex that everyone has; the clinical line is drawn at how much they bother you, not a number.
Two exits, two sources
A burp is mostly air you swallowed. A fart is mostly gas your bacteria made. Grade: Moderate to strong — long-standing physiology, repeated in gas-composition studies.
What leaves from below
Flatus is a mix of swallowed air (nitrogen, some oxygen) and fermentation gases: hydrogen, carbon dioxide and, in some people, methane. In the Sheffield study, a fibre-free liquid diet for 48 hours cut total output to a median 214 ml and practically eliminated hydrogen (Tomlin et al., 1991). What was left, around 200 ml a day, was the non-fermentation baseline.
None of the main gases smell. The odour comes from sulphur compounds present in tiny concentrations. When flatus was collected and scored by judges, hydrogen sulphide tracked most closely with malodour, followed by methanethiol and dimethyl sulphide (Suarez et al., 1998).
What leaves from above
Impedance studies show there are two quite different kinds of belch (Kessing, Bredenoord & Smout, 2014):
- Gastric belch. A vagal reflex relaxes the lower oesophageal sphincter and vents air from the stomach. This is the normal, protective burp.
- Supragastric belch. Air is sucked or pushed into the oesophagus from the throat and expelled before it ever reaches the stomach. This is a learned behaviour, not a reflex.
That distinction matters. People who belch excessively show more supragastric belches, not more gastric ones. Most "I can't stop burping" complaints are a habit loop, not a stomach producing too much gas.
What each says about your diet and gut
Burps mostly report on how you eat and breathe. Farts mostly report on what you eat and who lives in your colon.
| Signal | Most likely meaning | Grade |
|---|---|---|
| Frequent burping after meals | Swallowed air: eating fast, talking while eating, fizzy drinks, gum | Moderate |
| Burping that starts before or without food, worse when anxious | Supragastric belching habit | Moderate |
| More wind after beans, onions, wheat, lactulose | Normal fermentation of fibre and FODMAPs | Strong |
| Very little wind at all | Often a low-fibre diet rather than a healthy gut | Moderate |
| Constipation plus bloating | Possible methane-dominant pattern | Moderate |
| Particularly foul-smelling wind | More sulphur-gas production | Moderate |
| Can never burp, gurgling in chest, lots of wind below | Retrograde cricopharyngeus dysfunction (see below) | Moderate |
Two points deserve expanding.
Methane and slow transit. A meta-analysis of nine studies (1,277 people) found methane on breath testing was linked to constipation, with an odds ratio of 3.51 (Kunkel et al., 2011). Eight further papers linked methane with slower transit. This is association, and methane didn't change flatus frequency in the Minneapolis data, but it's a consistent signal.
Gas as evidence of feeding. Almost all fermentation gas vanished on a fibre-free diet (Tomlin et al., 1991). Some wind is simply the sign your microbes are getting fibre. Treating zero gas as the goal pushes people towards the diet that feeds their gut least.
What happens when you hold it in
Deliberately clenching to stop wind leaving causes gas to pool, the belly to distend, and symptoms to rise. Grade: Moderate for the short-term effect — small, carefully controlled studies, mostly from one research group; Weak for any long-term harm.
The best data come from the Digestive System Research Unit at Vall d'Hebron in Barcelona, who spent two decades pumping measured gas into people's intestines and collecting what came out.
The system copes well when the exit is open. In 46 healthy people, gas was infused into the small intestine at rates up to 30 ml a minute for three hours. Evacuation quickly matched infusion and most felt nothing. Of the few who retained more than 400 ml, nearly all developed distension and symptoms (Serra, Azpiroz & Malagelada, 1998). Tolerance depends on transit, not volume.
Closing the exit on purpose. Ten healthy volunteers had gas infused, first while passing it freely, then while voluntarily restraining evacuation (Serra, Azpiroz & Malagelada, 2001). Holding it in raised retention from about 96 ml to 407 ml and increased girth. It also increased symptom scores. By contrast, when the same retention was produced with a drug that relaxed the gut, people barely felt it. Held-in gas hurts in a way that slack-gut gas doesn't.
People with IBS are hit harder. When gas was infused into 20 IBS patients and 20 controls, 18 of the patients developed retention, symptoms or distension, against 4 of the controls (Serra et al., 2001). A later study pinned the hold-up mainly on the small bowel, not the colon (Salvioli et al., 2005). So the people most likely to be anxious about wind are also the least able to tolerate keeping it in.
Meals change the picture. Fat reaching the duodenum slows gas transit and increases retention, while stomach stretch increases how much you feel it (Serra et al., 2002). Sitting through a rich dinner while suppressing wind combines both.
The stress of stifling
The effort of holding wind in is itself a stressor, and stress makes a sensitive gut feel more. Grade: Moderate — each link is evidenced, but no study has tested the whole loop.
The loop looks like this:
- Vigilance. You're in a meeting, on a date, in a quiet office. Attention goes to the gut and the sphincter.
- Clenching. Pelvic floor and glutes brace. Gas is retained, and retention caused by blocking the exit is the kind people feel (Serra et al., 2001).
- Stress response. In a St Mark's Hospital study, both physical and psychological stress altered gut blood flow in healthy people and in IBS. In the IBS group, stress also lowered the thresholds for rectal sensation and pain by roughly 20–30% (Murray et al., 2004).
- Altered breathing and posture. Bracing and shallow breathing feed into the abdominal wall pattern that produces visible distension (next section).
- Air swallowing. Anxiety increases swallowed air and is a common trigger for the supragastric belching habit (Zad & Bredenoord, 2020).
The result is more gas perceived, more distension, and more anxiety about the next occasion. For a healthy gut this is a nuisance. For someone with IBS or functional bloating, it's a plausible maintaining factor.
Distension isn't just gas
Much visible bloating is a muscle pattern, not volume. In abdominophrenic dyssynergia, the diaphragm pushes down and the front abdominal wall relaxes after meals. In a randomised placebo-controlled trial, biofeedback teaching 19 patients to move the diaphragm correctly cut their distension scores by about two-thirds (Barba et al., 2024). Placebo capsules did nothing. The way you hold your trunk while suppressing wind matters.
When holding it in genuinely helps
There is one well-evidenced case where stifling the urge is the treatment: supragastric belching. Grade: Moderate — two randomised trials and specialist consensus.
Because supragastric belching is a learned habit, the "better out than in" instinct keeps it going. Each deliberate burp brings in more air for the next. Supragastric belches can also trigger reflux and regurgitation episodes (Kessing, Bredenoord & Smout, 2014).
The fix is to interrupt the urge, not to vent it:
- In a Finnish randomised trial, five sessions of behavioural therapy built around diaphragmatic breathing reduced belching frequency and intensity versus no treatment. Three-quarters of patients responded, and depression scores fell (Punkkinen et al., 2022).
- A 2026 Chinese randomised trial in 72 patients found structured singing therapy beat diaphragmatic breathing: 72% versus 39% responded after one week, and 50% versus 31% at one month (Shang et al., 2026).
- A 2026 review of belching disorders confirms behavioural treatment as the mainstay for supragastric belching (Liu et al., 2026).
A second, gentler case: babies. In a randomised trial of 71 mother–baby pairs, routine burping didn't reduce colic over three months and roughly doubled regurgitation episodes (Kaur, Bharti & Saini, 2015). Grade: Moderate — one trial, but it challenges a near-universal ritual.
What the evidence doesn't show is any benefit to routinely clenching against wind from below. Beyond social comfort, there's no health case for it.
Myths, graded
| Claim | Verdict | What the evidence says |
|---|---|---|
| Holding in wind causes diverticulitis or appendicitis | Myth | No human study links suppression to either. The proven effects are short-term retention, distension and discomfort. |
| Held-in gas has to come out eventually, one way or another | Partly true | Most does, later. Some is absorbed into the blood and breathed out, which is why breath tests work. Some is consumed by gut microbes (Mego et al., 2017). |
| Smelling farts is good for you | Myth | An Exeter–Texas team built AP39, a compound that delivers tiny doses of hydrogen sulphide inside cell mitochondria. In mouse cells under oxidative stress, low doses protected mitochondria and a higher dose inhibited them (Szczesny et al., 2014). Headlines turned this into "sniff your partner's wind". The Exeter researchers responded that "neither the papers nor the accompanying press release … makes any reference at all to cancer or to any health benefits from inhaling (sniffing) hydrogen sulfide", and that the work had not been tested in humans (quoted in a Black Dot Research fact-check, opened 29 Sep 2026). |
| Beans always cause loads of wind | Overstated | Across three feeding trials, fewer than half reported more wind from pinto or baked beans in week one, and only 19% with black-eyed peas (Winham & Hutchins, 2011). |
| If fibre gives you wind, stop the fibre | Myth | Gut bacteria adapt. With a daily prebiotic, gas production rose 37% at first, then returned to baseline within two weeks (Mego et al., 2017). |
| Everyone can burp | False | Retrograde cricopharyngeus dysfunction leaves people unable to burp from childhood, with chest gurgling, bloating and excess wind. Botox to the upper oesophageal sphincter restored belching in 92% at three months versus 0% of controls (Sanagapalli et al., 2025). |
| Burping after a meal is polite in China or the Middle East | Weak | Widely repeated, mostly anecdotal, and customs vary within countries. Not something to build an argument on. |
| Nothing reduces the smell | Myth | A charcoal-lined cushion absorbed over 90% of sulphur gases in a controlled test (Suarez et al., 1998). |
What you can actually do
The aim is not zero gas. It's gas that moves, doesn't hurt, and doesn't run your social life.
If burping is the problem
- Work out which kind it is. Burps that start without food, cluster when you're anxious, or come in rapid runs point to the supragastric habit.
- For that habit, practise diaphragmatic breathing when the urge comes, and consider singing-based practice (Shang et al., 2026). Resist venting. Moderate.
- For after-meal burping: eat more slowly, talk less mid-mouthful, and cut fizzy drinks and gum. Weak to moderate — sensible, but little trial data.
If wind from below is the problem
- Check you're actually above normal. Keep a simple three-day tally. Under 20 a day is within range (Furne & Levitt, 1996).
- Increase fibre and legumes gradually, and give it two to three weeks. The microbiota adapts (Mego et al., 2017). Moderate.
- If symptoms are significant, a supervised low-FODMAP trial with structured reintroduction can identify the worst culprits. The American College of Gastroenterology recommends a limited trial in IBS (Lacy et al., 2021). Don't stay restricted long-term.
- For odour, activated charcoal products work on the gas after it leaves you (Suarez et al., 1998).
For the holding-in problem
- Where you can, don't. Step out and let it go. The retention and pain data are clear.
- Unclench deliberately: soften the belly, breathe low into the diaphragm, relax the pelvic floor. This targets both the blocked exit and the muscle pattern behind visible distension (Barba et al., 2024).
- Move after meals. Even gentle pedalling while lying down cut gas retention and distension compared with rest (Dainese et al., 2004). A walk is also the easiest way to excuse yourself.
- Be wary of combining a large, fatty meal with a long period where you can't leave (Serra et al., 2002).
When it's worth testing
Most wind needs no test. Test when the pattern is persistent, painful, or comes with other symptoms, because then the question is why the gas behaves as it does.
See your GP first if gas or bloating comes with unintended weight loss, blood in your poo, vomiting, a swelling or lump in your tummy, or bloating that keeps coming back despite changing your diet (NHS). A lasting change in bowel habit or difficulty swallowing also needs a GP first (NICE NG12). If you cannot pass wind or poo at all, ask for an urgent appointment or call 111. Those need ruling out before anything functional.
| Pattern | What can help clarify it | Grade |
|---|---|---|
| Constipation, bloating, slow transit | Breath testing for methane and hydrogen (Kunkel et al., 2011) | Moderate |
| Wind and bloating that change with fibre or FODMAPs | Stool testing such as GI-MAP looks at microbial balance, digestion and inflammation markers alongside the diet history. Declared interest: GI-MAP is part of the testing I offer. No study has shown that a stool panel improves outcomes for wind or bloating, so this is practice judgement, not evidence | None cited |
| Excessive burping, unclear type | pH-impedance monitoring, which separates gastric from supragastric belches (Liu et al., 2026) | Moderate (the specialist reference method) |
| Never able to burp, gurgling in chest | High-resolution manometry with a fizzy-drink challenge (Sanagapalli et al., 2025) | Moderate |
| Visible distension after meals | Specialist assessment of the abdominal-wall pattern (Barba et al., 2024) | Moderate |
A test result is one part of the picture. It is read alongside what you eat, how you eat, how you breathe and how stressed you are — the sum of the parts, not one marker.
What we don't know
The short-term physiology is well mapped; the long-term and social questions largely aren't.
- Chronic suppression. Every holding-in study ran for hours, not years. Whether a lifetime of clenching changes gut or pelvic-floor function is unstudied.
- The full stress loop. Each link is evidenced separately. No study has followed people who routinely suppress wind to see whether the loop drives lasting symptoms.
- Small samples. Much of the gas-dynamics work uses 8 to 46 volunteers, often from one Barcelona group. The findings are consistent, but independent replication is thin.
- Normal belching. There's no agreed healthy count for gastric belches, so "excessive" is defined by distress.
- Social burden. How many people avoid work, travel or relationships because of wind anxiety is essentially unmeasured.
- Sulphur gases and gut health. Hydrogen sulphide matters for odour; its wider role in gut health in people is still being worked out.
Where the evidence runs out, this article says so rather than filling the gap with opinion.
References
- Barba E, Livovsky DM, Accarino A, Azpiroz F. Thoracoabdominal wall motion-guided biofeedback treatment of abdominal distention: a randomized placebo-controlled trial. Gastroenterology. 2024;167(3):538–546. doi:10.1053/j.gastro.2024.03.005
- Dainese R, Serra J, Azpiroz F, Malagelada JR. Effects of physical activity on intestinal gas transit and evacuation in healthy subjects. Am J Med. 2004;116(8):536–539. doi:10.1016/j.amjmed.2003.12.018
- Furne JK, Levitt MD. Factors influencing frequency of flatus emission by healthy subjects. Dig Dis Sci. 1996;41(8):1631–1635. doi:10.1007/BF02087912
- Kaur R, Bharti B, Saini SK. A randomized controlled trial of burping for the prevention of colic and regurgitation in healthy infants. Child Care Health Dev. 2015;41(1):52–56. doi:10.1111/cch.12166
- Kessing BF, Bredenoord AJ, Smout AJPM. The pathophysiology, diagnosis and treatment of excessive belching symptoms. Am J Gastroenterol. 2014;109(8):1196–1203. doi:10.1038/ajg.2014.165
- Kunkel D, Basseri RJ, Makhani MD, et al. Methane on breath testing is associated with constipation: a systematic review and meta-analysis. Dig Dis Sci. 2011;56(6):1612–1618. doi:10.1007/s10620-011-1590-5
- Lacy BE, Pimentel M, Brenner DM, et al. ACG clinical guideline: management of irritable bowel syndrome. Am J Gastroenterol. 2021;116(1):17–44. PMID 33315591. doi:10.14309/ajg.0000000000001036
- Liu K, Walsh E, Katzka D, et al. Diagnostic and management review of gastric and supragastric belching, aerophagia, and rumination syndrome. Clin Gastroenterol Hepatol. 2026;24(2):285–295. doi:10.1016/j.cgh.2025.08.012
- Mego M, Accarino A, Tzortzis G, et al. Colonic gas homeostasis: mechanisms of adaptation following HOST-G904 galactooligosaccharide use in humans. Neurogastroenterol Motil. 2017;29(9). doi:10.1111/nmo.13080
- Murray CDR, Flynn J, Ratcliffe L, et al. Effect of acute physical and psychological stress on gut autonomic innervation in irritable bowel syndrome. Gastroenterology. 2004;127(6):1695–1703. doi:10.1053/j.gastro.2004.08.057
- NHS. Bloating. Last reviewed 21 January 2026. nhs.uk/symptoms/bloating. Accessed 3 Oct 2026.
- NICE. Suspected cancer: recognition and referral (NG12). nice.org.uk/guidance/ng12. Accessed 3 Oct 2026.
- Punkkinen J, Nyyssönen M, Walamies M, et al. Behavioral therapy is superior to follow-up without intervention in patients with supragastric belching — a randomized study. Neurogastroenterol Motil. 2022;34(2):e14171. doi:10.1111/nmo.14171
- Salvioli B, Serra J, Azpiroz F, et al. Origin of gas retention and symptoms in patients with bloating. Gastroenterology. 2005;128(3):574–579. doi:10.1053/j.gastro.2004.12.047
- Sanagapalli S, Eid M, Kim MB, Tudehope F. Prospective controlled study of endoscopic botulinum toxin injection for retrograde cricopharyngeus dysfunction: the inability to belch syndrome. Am J Gastroenterol. 2025;120(9):2051–2058. doi:10.14309/ajg.0000000000003242
- Serra J, Azpiroz F, Malagelada JR. Gastric distension and duodenal lipid infusion modulate intestinal gas transit and tolerance in humans. Am J Gastroenterol. 2002;97(9):2225–2230. doi:10.1111/j.1572-0241.2002.05976.x
- Serra J, Azpiroz F, Malagelada JR. Impaired transit and tolerance of intestinal gas in the irritable bowel syndrome. Gut. 2001;48(1):14–19. doi:10.1136/gut.48.1.14
- Serra J, Azpiroz F, Malagelada JR. Intestinal gas dynamics and tolerance in humans. Gastroenterology. 1998;115(3):542–550. doi:10.1016/s0016-5085(98)70133-7
- Serra J, Azpiroz F, Malagelada JR. Mechanisms of intestinal gas retention in humans: impaired propulsion versus obstructed evacuation. Am J Physiol Gastrointest Liver Physiol. 2001;281(1):G138–G143. doi:10.1152/ajpgi.2001.281.1.G138
- Shang H, Ma H, Xu Z, et al. Singing therapy versus diaphragmatic breathing for supragastric belching: a multicenter randomized controlled trial. Clin Gastroenterol Hepatol. 2026 (online ahead of print). doi:10.1016/j.cgh.2026.03.047
- Suarez FL, Springfield J, Levitt MD. Identification of gases responsible for the odour of human flatus and evaluation of a device purported to reduce this odour. Gut. 1998;43(1):100–104. doi:10.1136/gut.43.1.100
- Szczesny B, Módis K, Yanagi K, et al. AP39, a novel mitochondria-targeted hydrogen sulfide donor, stimulates cellular bioenergetics, exerts cytoprotective effects and protects against the loss of mitochondrial DNA integrity in oxidatively stressed endothelial cells in vitro. Nitric Oxide. 2014;41:120–130. doi:10.1016/j.niox.2014.04.008
- Tomlin J, Lowis C, Read NW. Investigation of normal flatus production in healthy volunteers. Gut. 1991;32(6):665–669. doi:10.1136/gut.32.6.665
- Winham DM, Hutchins AM. Perceptions of flatulence from bean consumption among adults in 3 feeding studies. Nutr J. 2011;10:128. doi:10.1186/1475-2891-10-128
- Zad M, Bredenoord AJ. Chronic burping and belching. Curr Treat Options Gastroenterol. 2020;18(1):33–42. doi:10.1007/s11938-020-00276-0