there some research for u....
Causes of flatulence
Intestinal gas comes from exogenous (90%) and endogenous (10%)
sources. Exogenous gas is air that is ingested through the nose and
mouth. Endogenous gas is produced within the digestive tract.
The endogenous gases are produced as a by-product of digesting
certain types of food. Flatulence producing foods are typically
high in complex carbohydrates, and include beans, milk, onions,
yams, sweet potatoes, chickpeas, citrus rinds, chestnuts, broccoli,
cabbage, yeast in breads, etc.
In beans, endogenous gases seem to arise from oligosaccharides,
carbohydrates that are resistant to digestion: these pass through
the upper intestine largely unchanged, and when they reach the
lower intestine, bacteria feed on them, producing copious gas.
(McGee, 1984 pp.257-8 )
In the case of those with lactose intolerance (i.e., most
non-Caucasian humans), intestinal bacteria feeding on lactose can
give rise to excessive gas production.
Another source of excessive gas production in the stomach is
stress. Stressful situations can cause the stomach to produce gas.
Also, not only does tight clothing cause a gassy stomach to be
painful, it also can contribute to the production of gas.
The average person releases 1 to 3 pints (0.5 to 1.5 liters) of
flatus in 12 to 25 episodes throughout the day.
Interest in the causes of flatulence was spurred by high-altitude
flight and the space program; the low atmospheric pressure,
confined conditions, and stresses peculiar to those endeavours were
cause for concern. (McGee, 1984 pp.257-8 )
