Bloating & Gas: What Causes It?

What is bloating?

Bloating is the feeling of discomfort in the abdomen due to gas building up in the intestines. This buildup of gas can cause frequent burping (belching), flatulence, and feelings of cramping in the abdomen.

Gas in the intestines occurs when sugars, such as fructose, lactose, glucose, and sucrose, from the food we eat are not properly absorbed in the small intestine. Bacteria which make up the normal flora of the colon (large intestine) break down these sugars and release gases such as hydrogen, carbon dioxide, nitrogen, and methane. These gases are then expelled as flatulence.

Up to 30% of people in the West and about 15% in Asia have symptoms of bloating at some point in their lives ^[1]. This is more prevalent amongst people living with irritable bowel syndrome (IBS) and functional dyspepsia.

IBS is a condition of the large intestine that is characterized by chronic stomach cramps, bloating, and alternating diarrhea and constipation. Certain foods and stress can trigger symptoms, which can vary in severity. Functional dyspepsia is characterized by recurring symptoms of indigestion and burning abdominal pain without an obvious cause.

What causes bloating ^[2-7]?

1. Bacterial overgrowth

Normal gas-producing bacteria are present mostly in the colon and in small amounts in the small intestine. SIBO (small intestinal bacterial overgrowth) occurs when there is an abnormal increase in the number of bacteria in the small intestine. This can lead to a buildup of sugars, causing more gas to be produced.

2. Swallowing air

This occurs when a person ingests air while chewing gum, smoking, or drinking through a straw. This air builds up in the upper gastrointestinal tract and is expelled by burping.

3. Slow intestinal movement

Conditions such as gastroparesis (delayed stomach emptying) and chronic intestinal pseudo-obstruction (an intestinal disorder that mimics an intestinal obstruction or blockage) cause food to take longer to be broken down by the digestive system. This prolonged travel time causes a further breakdown of sugars, leading to an increased buildup of gas in the intestines.

4. Low carbohydrate absorption

Simple carbohydrates include lactose found in dairy products and fructose found in fruits. Some individuals have lower amounts of enzymes in the small intestine which help break down simple carbohydrates. For instance, individuals who have low amounts of the enzyme lactase develop an intolerance to lactose-containing foods.

5. Hard stool/ constipation

Infrequent bowel movements can also lead to bloating, as feces will be trapped in the colon for longer.

6. Medication use

Some antibiotics cleanse the body of both good and bad bacteria, and therefore can lead to a disruption of the normal gut flora. Though SIBO is treated with antibiotics, any long-term use of antibiotics can destroy the normal gut biome. Antacids, aspirin, and some pain medications can also cause bloating.

7. Diseases/ preexisting conditions

People with conditions such as IBS and functional dyspepsia frequently complain of bloating and abdominal pain. Bloating is also a significant symptom in women with endometriosis, a condition in which the uterine lining deposits on the intestine and elsewhere in the abdomen. This bloating is more apparent during menstruation.

Now that you know what some of the causes are for bloating and gas, take a look at part 2 to learn about tips to reduce/ prevent bloating altogether!

References:

1. Clinical Dimensions of Bloating in Functional Gastrointestinal Disorders. Journal of Neurogastroenterology and Motility. 2016. Cited 19 July 2021. Available from: https://www.jnmjournal.org/journal/view.html?doi=10.5056/jnm15167
2. Abdominal Bloating: Pathophysiology and Treatment. Journal of Neurogastroenterology and Motility. 2013. Cited 19 July 2021. Available from: https://www.jnmjournal.org/journal/view.html?doi=10.5056/jnm.2013.19.4.433
3. What is a gastrointestinal (GI) motility disorder? Wexner Medical Center. The Ohio State Medical University. Cited 19 July 2021. Available from: https://wexnermedical.osu.edu/digestive-diseases/gastrointestinal-motility-disorders
4. Pathophysiology, Evaluation, and Treatment of Bloating .Gastroenterology and Hepatology. 2011. Cited 19 July 2021. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3264926/
5. Polysaccharides – Fiber. Kansas State University.2020. Cited 28 July 2021. Available from: https://med.libretexts.org/Under_Construction/Purgatory/Book%3A_Intermediate_Nutrition_(Lindshield)/02%3A_Macronutrient_Structures/2.01%3A_Carbohydrates/2.1E%3A_Polysaccharides/1.03%3A_Polysaccharides_-_Fiber
6. Lactose malabsorption and intolerance: pathogenesis, diagnosis and treatment. United European Gastroenterology Journal. 2013. Cited 19 July 2021. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4040760/
7. Abdominal Bloating: An Under-recognized Endometriosis Symptom. Journal of Obstetrics and Gynaecology Canada. 2009. Cited 19 July 2021. Available from: https://www.jogc.com/article/S1701-2163(16)34377-8/fulltext