The fiber, starches and sugar found in foods high in carbohydrates are not digested in the small intestine when the right digestive enzymes are not available. These undigested substances move on to the large intestine, where they are broken down by friendly bacteria. The friendly bacteria produce methane when breaking down these foods during digestion. Over-the-counter digestive aids contain the enzymes necessary to prevent the gas.
Cruciferous (also known as brassicaceae or cruciferae) vegetables are part of a flowering plant family that causes gas in the digestive tract. Broccoli, cabbage, radishes, brussels sprouts and cauliflower are cruciferous vegetables. Other vegetables that produce gas when moving through the digestive process are onions, carrots, cucumbers and celery.
Gas-Producing High Fiber
Foods high in fiber are known a gas-producing agents in the digestive tract. Bran cereals, brown rice and whole wheat can cause intestinal gas while white rice does not. Legumes, which include beans (dried beans, green beans), peas and lentils are also high in fiber and produce gas as a by-product of digestion. Starches like potatoes, pasta and corn are also gas-producing foods.
The sugar (fructose) found in many fruits is known to cause gas. Raisins, apricots, dried fruits of all kinds, bananas and prunes produce gas. Fructose can be found as an ingredient in soft drinks and other processed foods.
Lactose intolerance (the inability to digest milk and dairy products) causes gas during digestion. Milk sugars found in dairy products like milk, ice cream and cheese cause the gas. Yogurts with active bacteria cultures may not cause gas because the bacteria aids the digestion process.