Bowel Gas And Bloated Stomach
Abdominal bloating is a condition in which the tummy feels full, tight and distended. It is also called meteorism and tympanites. Belching, flatulence and bowel movements relieve the symptom of bloating in most of the cases. The majority of conditions causing bloating are not serious and include conditions like aerophagia, in which abdominal bloating is caused by subconscious swallowing of air. 
The bowel of a normal person contains about 200ml of gas. About 600 ml of gas is evacuated as flatus (farts) everyday. The five main gases found in the bowel are nitrogen, oxygen, carbon dioxide, hydrogen and methane. Of these, nitrogen and oxygen are derived from swallowed air and the remaining gases are formed due to a fermentation process by bacteria in the large bowel. 
The excess gas in the upper gastrointestinal tract is released by belching. Flatulence is the volitional or involuntary release of gas from the lower gastrointestinal tract. On an average, a health individual passes flatus 14 times per day. Some even report 25 expulsions. 
Bloating is the perception of retained excess gas within the lumen of the gut. Women report bloating more often than men. Although some conditions lead to increased gas production, many individuals with bloating exhibit normal gut gas volumes.
What Causes A Bloated Stomach?
Abdominal bloating usually results from a disorder of the function of the gastrointestinal tract. Abdominal bloating could be due to any of the following causes :
- Subconscious swallowing of air – This is called aerophagia. This usually occurs during rapid eating and drinking, chewing gum, smoking and wearing loose dentures. This is more pronounced in nervous individuals. Most of the upper intestinal air is accumulated because of aerophagia.
- Irritable bowel syndrome – This is characterized by abdominal pain or discomfort associated with altered bowel habits. In this condition, the amount and distribution of gas in the gut will be normal. But due to increased sensitivity, there is increased awareness of gas and bloating. Sometimes certain fiber supplements used to treat irritable bowel syndrome and constipation can cause bloating.
- Constipation – Chronic constipation can cause a bloated stomach.
- Small intestinal bacterial overgrowth – This is a condition in which abnormally large amounts of bacteria are present in the small intestine. This interferes with digestion and absorption of nutrients and causes symptoms like bloating, abdominal and diarrhea.
- Excess gas in the bowel – It could be due to malabsorption of nutrients. This is seen in conditions like lactose intolerance. Malabsorption, in addition to abdominal bloating, also causes other symptoms like abdominal pain, weight loss and diarrhea. Sometimes overeating or eating excess of fatty food can cause similar symptoms. Fatty food delays emptying of the stomach and allows the gas to accumulate, causing bloating.
- Abnormal motility of the bowel – Conditions that affect the motility of the bowel can result in prominent gas and bloating. Gastroparesis is one of the common conditions that affect the motility of the gut, causing symptoms including bloating. Certain medications like opiates, calcium channel blockers, anticholinergics and antidepressants can affect the motility of gut, again causing abdominal bloating.
- Intestinal obstruction – If there is intestinal obstruction, it causes abdominal distention, vomiting and constipation. It is a more serious condition and immediate medical attention is necessary.
- Gas-bloat syndrome- It is a consequence of the fundoplication surgery for gastroesophageal reflux disease. Following this surgery, there will be an inability to belch or vomit. In the initial months after fundoplication, up to 20% experience bloating.
Abdominal bloating sensations need not be always due to gas in the bowel. Sometimes the tummy may feel full, tight and distended in other conditions as well which include:
- Ascites – In this condition, there is an accumulation of excess fluid which may be due to liver disease, kidney disease, cancer, or infection.
- Tumor – A tumor in the abdomen can cause distention and a tense feeling.
Ascites and tumors are usually reported as abdominal swelling and not as abdominal bloating. If the abdomen is more seen as distended it is more likely to be abdominal swelling rather than abdominal bloating. On the contrary, abdominal bloating is more felt than seen. About 25% of those who complain of abdominal bloating do not complain of abdominal distension. Up to 1400 ml of gas, which is about 7 times the normal gas level (200 ml), is required to cause an increase in the abdominal girth by 2 cm. 
Treatment Of A Bloated Stomach
Treatment depends on the underlying cause. The following is the treatment of each of the common causes of a bloated stomach.
- Aerophagia (Subconscious swallowing of air) - Behavioral modification is necessary to treat this condition .
- Avoid chewing gum
- Wear correctly fitting dentures
- Eat slowly
- Chew well
- Avoid hard candy
- Avoid carbonated drinks
- Irritable bowel syndrome - Low dose antidepressants and antispasmodics are used to treat irritable bowel syndrome. Recent meta-meta-analyses have indicated the benefit of antibiotics, probiotics, and anti-tumor necrosis factor agents in IBD .
- Constipation – Osmotic laxatives and plenty of fluids will be helpful. Certain fiber supplements like psyllium should be avoided as they can worsen bloating. 
- Small intestinal bacterial overgrowth – It is treated with a course of antibiotics. For example, an analysis of small bowel biopsies in elderly patients with small intestinal bacterial overgrowth revealed blunting of the intestinal villi, thinning of the mucosa and crypts, and increased intraepithelial lymphocytes. All of these symtoms reversed with antibiotic treatment. 
- Malabsorption syndrome – Nutrients that are not absorbed well are eliminated from the diet. For example, lactose is to be avoided in lactose intolerance and gluten in case of celiac disease. Alternatively, digestive enzymes (like lactase enzyme for lactose intolerance) can be taken for relief. 
- Abnormal motility of gut – Diabetes mellitus is a risk factor for the development of gastroparesis, which is a chronic disorder that affects a significant part of the population. Gastroparesis is treated with prokinetics like metaclopramide. If abnormal motility is due to medications, one should investigate alternative options. 
- Intestinal obstruction – Surgery is done to treat this condition. 
In addition to the treatment mentioned above which is directed towards the specific underlying cause, there are a few other treatment options which treat the symptom of bloating. This includes:
- Gas-forming items should be avoided which include whole wheat, milk and milk products, sugar-free candies, beans, cabbage, and broccoli. Alternatively, Beano or Fiberease can be taken to prevent gas formation. Five drops or one tablet of Beano per serving helps prevent gas formation. Fatty foods should also be avoided.
- Simethicone and activated charcoal help in reducing bowel gas .
- Drinking Fennel tea may relieve the symptom of bloated stomach.