Most of the colonic gas is the consequence of bacterial action on food residues in the lower small intestine and colon. This is commonest factor involved. It may be due to faulty dietary habits such as eating fast, excessive consumption of carbonated drinks or tobacco or spicy foods. Anxiety, grief, nervous tension play an important role. Diseases such as gastritis, peptic ulcer, may lead to flatulence.
Mouth breathing is also a common factor.
This is the commonest pre-disposing factor and the most neglected too. Foods into which air is whipped e.g. dhokla, dosa etc. The signs and symptoms here probably need no introduction. But, persistent flatulence not responding to home remedies should make you cautious to seek professional advice, since it may be a symptom of an underlying disease such as gastritis, peptic ulcer, cholecystitis, hiatus hernia etc. Plain X-ray of abdomen will reveal an underlying disease if there is any.