Flatulence, also known as ‘breaking wind’, ‘passing wind;’ or farting, is an excess of gas in the intestines. Flatulence can be an embarrassing problem for some people.
How much gas is normal?
It is normal for gas in the digestive tract to be passed out through the rectum (as flatus) on average between 14 and 25 times a day, depending on your diet. A high fibre diet will produce more gas than a diet containing less fibre. The normal amount of gas produced per day ranges from 250 mL to 2500 mL.
Symptoms of flatulence
Some symptoms that can accompany excessive flatulence include:
- bloating and discomfort;
- belching; and
- pain in the abdomen.
What causes flatulence?
Possible causes of flatulence include:
- High-fibre diet: A diet containing foods high in soluble fibre.
- Increase in fibre: A sudden increase in the amount of fibre in the diet.
- Swallowing excessive air: It’s normal to swallow some air, but excessive swallowing of air can be due to chewing gum, sucking pens or pencils, smoking and not taking the time to chew food slowly.;
- Medical conditions. Some medical conditions, such as coeliac disease, lactose intolerance, Crohn’s disease or ulcerative colitis.
- Lack of digestive enzymes. If a person is lacking in the enzymes needed for digestion, undigested food passes into the intestine and then bacteria break it down releasing gases.
- Long transit time through the intestine. This gives bacteria more chance to ferment the waste products, producing unpleasant gas.
- Medicines. Some medicines may cause flatulence as a side-effect, e.g. statins, varenicline (Champix) – the anti-smoking medicine, and some laxatives.
- FODMAP (Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyphenols) intolerance. Some people are sensitive to foods containing FODMAPs and will produce a lot of gas when the FODMAPs are fermented by bacteria in the large bowel.
Foods causing wind
Reactions to different foods may vary from person to person. Some foods that may cause flatulence include:
- vegetables such as cabbage, cauliflower, broccoli, onions, asparagus and brussels sprouts;
- fruits such as peaches, apples and pears;
- fizzy drinks;
- foods containing the sugar lactose, such as dairy products like milk;
- sugar-free confectionery and chewing gum, which contain sorbitol;
- whole grains such as bran and wheat; and
- beans and pulses.
Swallowing excess air
Swallowing excess air is a cause of flatulence and may be caused by:
- chewing gum;
- ill-fitting false teeth;
- eating too quickly or talking while eating; and
- anxiety and stress.
Medical conditions in which digestion of foods is impaired, such as Crohn’s disease, ulcerative colitis and coeliac disease, often result in excess wind being produced in the gut.
Also, people who lack, or have deficiencies in, the enzyme that breaks down lactose in the gut will find that they produce excess gas when they consume foodstuffs containing lactose. These foods include milk and dairy products. This condition is known as lactose intolerance.
What makes it smell?
As bacteria in the large intestine ferment your food, they produce gases. Nitrogen, oxygen, carbon dioxide, hydrogen and methane make up 90 per cent of the gases and are odourless (have no smell). The remaining 10 per cent consists of other gases.
Any odour in the gases, which are subsequently released as flatus, is caused by sulphur-containing gases, such as hydrogen sulphide (rotten egg gas), released by the bacteria.
People differ in the composition of the bacterial populations in their intestines, and this affects how a person breaks down foods in their intestine, and the gases produced. So not everyone reacts in the same way to the same food.
Self-help to reduce flatulence
There are a number of measures you can try if you are suffering from embarrassing or excessive flatulence.
Charcoal tablets or activated charcoal tablets. These tablets are available over the counter from pharmacies. Charcoal has the ability to bind and trap other substances and then remove them from the body. Charcoal can absorb gas in the bowel, thus helping with the symptoms of excessive flatulence. People who are on other medications should not take charcoal tablets, because of the risk of the charcoal binding the medication and removing it from the body, making it less effective or not effective at all.
Avoid dairy if you are lactose intolerant. If you are lactose intolerant, avoid foods containing lactose, such as dairy foods.
Antacids can help to reduce flatulence. Some antacids contain simethicone (e.g. De-Gas, Dulcogas) which breaks down the surface tension of gas bubbles, allowing them to break down. You can get antacids over the counter or from your local pharmacist.
Dietary modification. You may get some relief from excessive flatulence by modifying your diet to include fewer foods that contain compounds which result in excessive flatus for you. Common culprits are onions, lentils and beans.
Avoid sugar-free chewing gum and sweets. These often contain sorbitol – which is a sweetener that can cause flatulence.
When to see a doctor about your flatulence
If you are experiencing excessive flatulence, talk to your doctor or dietitian. They can advise you on medications and lifestyle changes — such as eliminating certain foods from your diet — that may help alleviate the problem, and can help rule out other serious intestinal problems.
Signs that you should seek medical advice are persistent or severe flatulence, especially if it’s associated with vomiting, constipation or diarrhoea, heartburn, persistent bloating, weight loss or blood in your stool.
Are there any diagnostic tests for excessive flatulence?
There are no specific investigations for excessive flatulence. Your doctor will probably take a history of your symptoms, and may even ask you to record your symptoms in a diary, along with any other relevant information. Your doctor may want to do tests to try to eliminate any health conditions as the cause of your excessive flatulence.
Last Reviewed: 18/02/2016
1. NHS Choices. Flatulence. http://www.nhs.uk/Conditions/Flatulence/Pages/Introduction.aspx (accessed Feb 2016).
2. Mayo Clinic. Intestinal gas. http://www.mayoclinic.org/symptoms/intestinal-gas/basics/definition/sym-20050922 (accessed Feb 2016).
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