According to the Mayo Clinic, excessive gas is caused by high-fiber foods, fiber supplements, carbonated drinks, chronic issues such as diabetes and an inflammatory bowel disease, swallowing more air than usual, constipation, and system intolerance of certain foods and artificial additives. WebMD also notes that tumors causing intestinal blockage can lead to excessive gas.
The Mayo Clinic says that foods such as whole grains, legumes, fruits and vegetables often lead to excessive gas. Fiber supplements should be introduced to the diet gradually to avoid causing too much gas. WebMD points to cauliflower, broccoli, onions and artichokes as some vegetables that cause excessive gas. It recommends keeping a food journal to identify foods that may be causing excessive gas. WebMD also notes that lactose-intolerant people may have excessive gas after consuming dairy products.
WebMD notes that some people are more prone than others to swallow air excessively, leading to higher levels of gas. Air is sometimes swallowed via a straw, eating or drinking too fast, gum chewing, loose dentures and sucking on candies. People who have sinus infections or allergies also swallow air more frequently. Also, people who have serious heartburn are more prone to swallowing air, which can force air down to wash acid back into their stomachs.