Digestion breaks food down into proteins, carbohydrates, fats, and other nutrients. Food and liquids enter the mouth, then travel to the stomach through the esophagus. A few enzymes in saliva and a mix of substances in the stomach begin digesting the food. The digestive enzymes in the small intestines can't break down certain types of fiber. Therefore, bacteria in the intestinal tract absorb the indigestible fiber and convert it to gas. Most people produce one to three pints and pass gas 14 to 23 times per day.

Gas In the Stomach

Aerophagia is the medical term for swallowing air, which everyone does while talking, eating, and drinking. An excessive quantity enters the esophagus when we chew gum, drink carbonated beverages, and eat or drink too quickly. We release most of this excess air by belching, but some of it travels through the digestive system to emerge as flatulence.

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Gas Composition

Flatulence is made up of carbon dioxide, oxygen, hydrogen, nitrogen, and sometimes methane. Nitrogen accounts for approximately half the total volume of flatulence. The body makes every component except nitrogen, which comes from inhaled air. Methane production is less common. In fact, some people produce flatulence that is free of methane.

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Sulfur compounds make up only one percent of typical flatulence, but each has a distinct odor. Hydrogen sulfide is the most common compound and produces the familiar rotten egg odor, accounting for most of the bad smell we associate with the action. Methanethiol produces an odor similar to rotting vegetables or garlic. Dimethyl sulfide smells like cabbage, and some people describe it as sweet.

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The types of bacteria in each person's digestive tract determine which sulfur compounds are present. The pungency or strength of flatulence varies according to the time required for digestion. Bacteria produce gases and sulfur compounds as food matter moves through the intestines. The odor is stronger when food is in the intestines for a long time. Drinking lots of water and eating foods with high fiber content decreases the length of time food remains in the intestines.

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FODMAP is a hard-to-digest carbohydrate that increases the production of flatulence. Foods high in FODMAPs include legumes, sugar alcohols, wheat, barley, rye, garlic, onions, asparagus, some fruits and fruit juices, milk, and yogurt. FODMAP is not broken down in the small intestine, so it is digested entirely within the large intestine. Most people experience a very mild increase in gas production in response. Abdominal pain and bloating after eating these foods may indicate intolerance.

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It is normal to experience occasional abdominal discomfort, short-term pain, and bloating related to flatulence. Women are especially prone to bloating and increased flatulence during menstruation. Changes in diet, minor illnesses, lack of sleep, and numerous other factors may cause temporary changes in gas production. Severe symptoms include constipation or diarrhea for three days or more, blood in stools, vomiting, and severe pain or bloating in the abdomen. These symptoms, in conjunction with increased flatulence, should be reported to a physician.

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Symptoms of indigestion include bloating, nausea, vomiting, an acidic taste, belching, abdominal pain, and increased flatulence. Specific foods and beverages or emotional stress and anxiety can cause acute incidents of indigestion. Indigestion usually has mild symptoms, but it is sometimes the start of more serious disorders such as irritable bowel syndrome, ulcers, or stomach cancer.

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Food Intolerances

Lactose intolerance results from a lack of the enzymes necessary to digest milk sugars. The undigested sugars in the large intestine prompt increased bacterial activity and gas with a strong odor. Dairy products cause diarrhea, flatulence, abdominal pain, and nausea. Vomiting is possible but not common. People affected by carbohydrate malabsorption cannot digest certain dietary carbohydrates in foods. Carbohydrate intolerance may be congenital and diagnosed during childhood or acquired later in life. Lactose intolerance is an example of acquired carbohydrate intolerance that usually appears during adulthood. The most severe form of carbohydrate malabsorption is Celiac's disease, a secondary form of carbohydrate malabsorption that comes from damage to the small intestinal lining due to exposure to gluten. Just a trace of gluten-containing grains can trigger symptoms for people with this chronic condition.

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Related Conditions

Long-term or frequent increases in flatulence may be a sign of more serious disorders. Gastroenteritis or stomach flu is a viral infection characterized by inflammation of the stomach and intestines, causing abdominal pain, bloating, and diarrhea. Crohn's disease is an inflammatory disorder of the digestive tract with symptoms such as abdominal pain and bloating, chronic diarrhea, rectal bleeding, and poor digestion. Pancreatitis and diverticulitis also have similar symptoms.

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Hypoactive Bowel Sounds

Medical professionals often use a stethoscope to listen for bowel sounds in all four abdominal quadrants during exams. Reduced or absent bowel sounds are called "hypoactive" and indicate slow or stopped intestinal activity. These noises are expected for a short time after certain surgeries but indicate constipation or bowel obstruction in routine circumstances. Ileus is a condition characterized by a lack of intestinal activity and can result in an accumulation of gas, fluids, and other contents in the intestines. Severe ileus can cause bowel wall ruptures.

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