Foods that cause excessive gas include beans and lentils, fructose and sorbitol present in fruits and sweeteners, and dairy products that contain lactose, as Mayo Clinic explains. Carbohydrates can also cause excessive gas. Foods that often cause gas include carbonated drinks, onions, whole grains, milk products and fruits, such as peaches, apples and pears.
Certain vegetables, such as lettuce, cauliflower, cabbage, brussels sprouts and broccoli, can increase the amount of gas in the body, according to Mayo Clinic. Hard candy, sugar alcohols and chewing gum also produce excess gas when the body is unable to digest these foods properly.
Patients can prevent excess gas by drinking and eating slowly to reduce the amount of air swallowed, as pointed out by Mayo Clinic. It is best to avoid beer and carbonated drinks because these beverages release carbon dioxide gas. Smoking also leads to an excess amount of swallowed air that can cause excess gas.
People with excess gas caused by swallowing additional air suffer from upper intestinal gas, whereas lower intestinal gas develops when food fails to digest or break down properly by the time it reaches the colon, explains Mayo Clinic. Intestinal gas consists of carbon dioxide, hydrogen or methane.