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What’s causing your gas and flatulence?

29 Sep 2020

Trapped wind can be embarrassing and painful. It can also have many causes — from food to underlying conditions. Here’s a guide to dealing with flatulence

Quick facts

  • The average adult breaks wind 12-25 times a day
  • Sweeteners ending with ‘-tol’ are hard-to-digest sugar alcohols which can cause flatulence
  • Excessive flatulence might be down to an underlying condition

It’s normal to pass wind now and then, but when it happens frequently it can undermine your confidence. And while it varies between individuals, on average we emit gas from our mouth or bottom between 12 and 25 times a day.

Why wind happens

Gas builds up in the digestive tract in two ways: by swallowing air or as a by-product of gut bacteria breaking down foods. Having some gas is inevitable and perfectly normal, but having a lot could be a sign of an underlying problem.

During digestion, chemicals called enzymes break down foods so they can be absorbed in the small intestine. During this process, some undigested sugars, starches and fibres reach the large intestine. There, they ferment as bacteria in the gut try to break them down. This produces gases, including carbon dioxide and hydrogen sulphide, which are released as flatulence.

Causes of excess wind and flatulence

Everyone passes wind and many factors, from your genes to an underlying condition, can lead to increased gas and flatulence. But you can reduce unwanted emissions — the first step is to identify the source of the problem. Here are some of the likely reasons:

Eating or drinking too quickly makes us swallow air, which is then released as burps and belches. Swallowing air, or aerophagia as doctors call it, can also be caused by chewing gum, smoking, having a blocked nose and wearing dentures that don’t fit properly.

Foods that trigger flatulence include cabbage, cauliflower, Brussels sprouts, broccoli, dried fruit and beans because they tend to contain a lot of hard-to-digest fibres and sugars. But these are incredibly important in the diet, particularly for detoxification of the liver. So, if you suspect these foods, before you cut them out, keep a diary and list your symptoms after eating different foods. It could be that only particular vegetables or bean types cause problems. Raw vegetables such as cabbage might be problematic for you, but lightly steamed may not — so note down how you react in relation to the cooking method of the food you’re consuming too.

Sweeteners such as xylitol and sorbitol — which are commonly used in reduced-calorie drinks, chewing gums, sweets, cakes and biscuits — cause flatulence because we lack the enzymes needed to digest them. Any sweetener ending with ‘-tol’ can cause problems.

Fructose is a fruit sugar found in table sugar, sweeteners and syrups, dried fruits, juices and other processed foods and drinks. Our bodies can’t digest too much fructose at one time, and it can add up quickly in our bodies. An apple, or a 200ml glass of orange juice, both have around 6g of fructose and some carbonated drinks have up to 50g for a single can or bottle. For many of us, undigested fructose reaches the large intestine — where it ferments and produces gas.

Gut bacteria play a key role in digestion. Around 500 different bacteria species are found in the large intestine and everyone’s microbiome — as this mix of bacteria is known — is unique.

As bacteria interact with undigested carbohydrates in the gut, they produce a range of different gases and these can lead to flatulence.

Our microbiome is influenced by our diet, lifestyle and use of antibiotics can lead to significant changes in the gases we produce. That’s why antibiotics can sometimes cause flatulence, and why probiotics — which contain so-called friendly bacteria — can improve the balance of beneficial bacteria and reduce flatulence and other gastric symptoms. Probiotic drinks and yogurts are readily available, and fermented foods such as sauerkraut and kimchi also provide probiotics.

Medicines including ibuprofen, statins and antifungals can sometimes cause flatulence. Speak to your doctor if you suspect a medicine you take regularly is causing problems.

Irritable Bowel Syndrome (IBS) affects as many as 1 in 5 people and can arise from food passing through the gut too quickly or slowly, overly sensitive nerves in the gut, food intolerances and stress. It can also cause stomach cramps, bloating, diarrhoea and constipation. These tend to come and go over time, and episodes can last for days, weeks or months. Talk to your doctor, who can suggest a management plan. This may include adherence to an eating plan known as the FODMAPs diet, which has been clinically shown to help with IBS symptoms, however it must be followed with the supervision of a dietitian.

Lactose intolerance occurs when we don’t make enough lactase, the enzyme needed to break down and digest milk sugars. Warning signs include excessive flatulence as well as diarrhoea, bloating, stomach pain or feeling sick after consuming lactose-containing dairy foods such as milk and cheese. Talk to your doctor if you suspect you might have it.

Coeliac disease occurs when your immune system reacts to gluten found in many foods. It can cause symptoms such as flatulence, bloating, constipation, diarrhoea, weight loss and skin problems. It affects around 1 in 100 people and often runs in the family. A doctor can diagnose coeliac disease with a simple blood test.

6 simple steps to help reduce flatulence

  1. Keep a food diary to identify foods that cause wind — and avoid them.
  2. Eat smaller meals, more often — and chew food slowly. This gives the amylase in saliva more time to start breaking down carbohydrates which can help prevent excess wind.
  3. Drink plenty of water — this reduces the risk of constipation and keeps things moving.
  4. Drink peppermint tea — it contains essential oils which have been shown to reduce flatulence and bloating.
  5. Exercise to improve digestion — studies confirm light exercise, such as walking or a gentle bike ride, will reduce symptoms. It’s believed exercise helps matter move through the intestine so it may aid constipation too.
  6. Check your fibre intake — most of us don’t eat enough fibre. Around 30g a day is recommended. Fruits, vegetables and wholegrains such as wholemeal bread, oats and quinoa are good sources.

Speak to your doctor if you have other symptoms such as bloating, pain, diarrhoea, constipation,chronic belching or there’s blood in your poo – these could be a sign of something more serious.

Reviewed by Dr Rhianna McClymont, Lead GP

Last updated:
29 Sep 2020

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