Irritable Bowel Syndrome (IBS): This is the most common cause of excess intestinal flatulence due to its high prevalence and the fact that it often presents with bloating and gas as primary symptoms.

Lactose Intolerance: A common condition where individuals are unable to digest lactose, leading to bloating, gas, and flatulence after consuming dairy products.
Fructose Malabsorption: Similar to lactose intolerance, some people cannot properly absorb fructose, leading to gas and bloating.
Small Intestine Bacterial Overgrowth (SIBO): An overgrowth of bacteria in the small intestine can lead to excessive gas production, causing bloating and flatulence.
Food Intolerances: Intolerances to foods such as gluten (in non-celiac individuals), high FODMAP foods, or other specific dietary components can cause gas and bloating.

Celiac Disease: An autoimmune disorder where the ingestion of gluten leads to damage in the small intestine. It can present with malabsorption, including bloating and gas, and if missed, can lead to severe complications.
Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause significant gastrointestinal symptoms, including gas and bloating, and require prompt diagnosis and treatment to prevent serious complications.
Gastrointestinal Obstruction: Although less common, a mechanical obstruction in the intestine can cause severe bloating and gas and is a medical emergency.

Carbohydrate Deficiency: Rare enzyme deficiencies (e.g., sucrase-isomaltase deficiency) can lead to the inability to digest certain carbohydrates, resulting in gas and bloating.
Short Bowel Syndrome: A condition where a significant portion of the small intestine is missing or not functioning, leading to malabsorption and potential gas and bloating.
Gastroparesis: A condition where the stomach takes too long to empty its contents, which can lead to bloating and gas, although it is less commonly associated with flatulence as a primary symptom.