Ever been in a situation where passing wind is going to be hugely embarrassing and you’ve had to hold in a fart? Let’s face it – we all have. But is it safe?
Trying to hold it in leads to a build up of pressure and major discomfort. A build up of intestinal gas can trigger abdominal distension, with some gas reabsorbed into the circulation and exhaled in your breath. Holding on too long means the build up of intestinal gas will eventually escape via an uncontrollable fart.
The research is not clear on whether the rise in pressure in your rectum increases your chance of developing a condition called diverticulitis, where small pouches develop in the gut lining and become inflamed – or whether it doesn’t matter at all.
What is flatus?
As your body digests food in the small intestine, components that can’t be broken down move further along the gastrointestinal track and eventually into the large intestine called the colon.
Intestinal bacteria break down some of the contents by fermentation. This process produces gases and by products called fatty acids that are reabsorbed and used in metabolic pathways related to immunity and preventing disease development.
Gases can either be reabsorbed through the gut wall into the circulation and eventually exhaled through the lungs or excreted via the rectum, as a fart.
How much flatus is normal?
It can be challenging for researchers to get people to sign up for experiments that measure farts. But thankfully, ten healthy adults volunteered to have the amount of gas they passed over a day quantified.
In a 24-hour period all the flatus they expelled was collected via a rectal catheter (ouch). They ate normally but to ensure a boost in gas production they also had to eat 200 grams (half a large can) of baked beans.
The participants produced a median total volume of 705ml of gas in 24 hours, but it ranged from 476ml to 1,490ml per person. Hydrogen gas was produced in the greatest volume (361ml over 24 hours), followed by carbon dioxide (68ml/24 hr). Only three adults produced methane, which ranged from 3ml/24 to 120ml/24 hr. The remaining gases, thought to mostly be nitrogen, contributed about 213ml/24 hr.
Men and women produced about the same amount of gas and averaged eight flatus episodes (individual or a series of farts) over 24 hours. The volume varied between 33 and 125 ml per fart, with bigger amounts of intestinal gas released in the hour after meals.
Gas was also produced while they were asleep, but at half the rate compared to during the day (median 16ml/hr vs 34ml/hr).
Fibre and flatus
In a study on dietary fibre and flatus, researches investigated what happens to intestinal gas production when you put people on a high-fibre diet.
The researchers got ten healthy adult volunteers to eat their usual diet for seven days while consuming 30 grams of psyllium a day as a source of soluble fibre, or not. In the psyllium week, they were asked to add 10 grams – about one heaped tablespoon – to each meal.