Breaking wind, letting rip and plain old farts; for a bodily process we like to pretend never happens we have an awful lot of words to describe it.
This rich, and frequently juvenile, vocabulary is indicative of the sheer variety of flatulence that we humans are capable of.
And yet, apart from suspecting that the more beans we eat, the more we fart, do we know what is a normal level of flatulence – and when should we worry?
What causes flatulence?
There are two main causes. The first is that when the bacteria in the colon goes to work on the food we’ve eaten, the process of digesting and breaking it down releases gas.
“Gas produced in the colon then finds its way down towards the anus where it can be passed,” explains Dr Marion Sloan, a GP and chairman of the Primary Care Society for Gastroenterology.
The second cause of flatulence is swallowing when we’re eating. “We don’t take mealtimes very seriously,” says Dr Sloan. Sitting at our computers or playing on our phones means we swallow air. That air accumulates in the stomach and is released as either a burp, or it passes down through the bowel and out of the other end.
What’s ‘normal’?
The average person passes gas roughly 13 to 21 times a day as a natural part of the process of digesting the food they’ve eaten.
Perhaps surprisingly, flatulence is not actually a sign of anything wrong, says registered dietitian Jo Travers of gut-health initiative Love Your Gut. “It actually shows that you have been eating foods that contain fermentable carbohydrates, which feed the bacteria in your gut.”
Gut bacteria feed on these carbohydrates, producing gas as a by-product. Fruits, vegetables, wholegrains and plant proteins like beans and lentils are full of these fermentable carbohydrates and they are really good for us.
Most gas passed during flatulence goes unnoticed because there isn’t a smell. Nitrogen, oxygen, hydrogen, carbon dioxide and methane are all odourless. However some foods result in hydrogen sulphide and ammonia, which is formed by gut bacteria, and gives farts their smell.
“Everyone has a unique microbiome that produces different smells,” says Travers.
Sudden dietary changes can lead to increased bouts of flatulence though. “Different foods get fermented to different gases which smell different, but there’s no evidence to say a particular smell means there’s a problem with your gut health,” says Travers.
“If you are eating cabbage for example there’s a lot of sulphur in cabbage and the gas that’s created from that is hydrogen sulphide, which really smells offensive,” says Dr Sloan.
It’s not a reason to stop eating leafy greens, though. Other examples of high-sulphur foods are eggs, poultry and fish, and allium plants such as garlic, onions, and leeks, as well as cruciferous vegetables like kale, cabbage and broccoli.
“If you’re doing some smelly farts it doesn’t mean you’re eating a bad diet. To the contrary, it means you’re eating a good diet,” says Dr Sloan.
People often think of baked beans and cabbage when they think of gas-producing foods, but, says Travers: “Fruit is also a cause which many people find surprising. And fizzy drinks may cause excess gas production too.”
A bit of bloating after eating is also normal, if a little uncomfortable at times.
What’s not normal?
While flatulence isn’t a cause for concern, there are some signs that you should pay attention to.
Excessive flatulence that presents with persistent pain or changes in bowel habits may require medical attention. “If you’re experiencing other gut symptoms like consistent stomach ache or bloating, constipation, diarrhoea, unexplained weight loss or blood in your poo for three weeks or more, you should consult your GP,” says Dr Johannes Uys, a doctor at Broadgate GP in London.
If you’ve taken antibiotics that have destroyed the good bacteria in your microbiome then you might end up with rogue bacteria that causes diarrhoea and flatulence.
“This is called dysbiosis. The lovely function that was there, digesting and creating all these good things along with a bit of flatulence is completely upended to a point where your bowel is running all over the place,” explains Dr Sloan.
Thankfully it’s quite unusual.
What to do if it’s not normal
There are some easy things you can try to stop excessive wind, says Dr Uys.
“Make sure you eat slowly and chew your food thoroughly. You should also avoid consuming fizzy drinks or taking deep breaths while eating, as carbonated beverages and swallowed air have both been found to exacerbate symptoms of flatulence.”
He advises patients suffering from digestive issues to keep a food diary tracking their diet’s impact on their flatulence levels. Certain foods, like beans, onions and dairy products, are common triggers for excessive gas production.
Many people who suffer from excessive bloating end up following a Fodmap diet. This in itself isn’t desirable, says Dr Sloan.
“Fodmap stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols. If you Google it a lot of foods come up, and we don’t necessarily want to be cutting all these foods out unnecessarily, and they contain valuable nutrients,” she says. In which case it’s worth taking one food item out at a time and then reintroducing it until you know what is causing the problem,
Dr Sloan calls irritable bowel syndrome, a common condition that affects the digestive system, “the joker in the pack”: “It’s not a serious disorder but it causes a lot of emotive and intrusive symptoms.”
Her advice is to seek support and self help through the IBS network. However, she adds: “If you’re losing weight or are short of breath, then I think that in itself would warrant visiting a healthcare professional. Just make sure you’re not missing any red flags.”
If you really need to, then she advises taking a product such as Bloateze, which is available over the counter and contains simethicone and carbon, a surfactant that breaks the bond that holds the surface of a bubble together: “So once the surface isn’t holding together all the bubbles burst and go to nothing,” she says. “That might help your trousers to fit, but really it’s nothing to worry about, it is just wind.”
Dr Sloan is not a fan of Pepto-Bismol – which contains bismuth subsalicylate and is used to treat heartburn, acid reflux, indigestion and diarrhoea – due to concerns about its heavy-metal content.
The serious things it can indicate
There are various bowel disorders where the fermentation process goes a bit rancid for different reasons.
“Take coeliac disease,” says Dr Sloan. “This presents as diarrhoea and often the reason for that is that the gluten damages the lining of the bowel, so things that should be digested and be absorbed in the upper part, end up in the colon that can’t cope with it and it rattles straight through you.”
The presence of blood in stool should not be ignored, as it could be a sign of heavy internal bleeding or irritable bowel disease, or cancer.
“IBD would normally present with diarrhoea and blood. Any blood would be a red flag and guarantee a primary-care opinion.”
A blood test would diagnose coeliac disease or cancer of the bowel. Women in their middle years should also be cautious around excessive bloating. “Cancer of the ovaries presents late and one of the main things that women describe is extreme bloating.”
Another serious condition is pancreatic insufficiency. “If the pancreas isn’t working for any reason the food doesn’t get digested and then great big lumps of undigested stuff arrive in the colon and the colon can’t cope with it. Thankfully it’s rare.”
