Symptoms
Intestinal gas
Causes
By Mayo Clinic Staff
Excess upper intestinal gas can result from swallowing more than a usual amount of air, overeating, smoking or chewing gum. Excess lower intestinal gas can be caused by eating too much of certain foods, by the inability to fully digest certain foods or by a disruption in the bacteria normally found in the colon.
http://www.mayoclinic.org/symptoms/intestinal-gas/basics/causes/SYM-20050922
