Those most affected are Orientals, Blacks, and Eastern Europeans. The undigested lactose is converted into hydrogen by the bacteria in the large bowel. The amount of gas produced depends upon the amount of milk ingested. Symptoms of bloating, abdominal cramps, and increased passage of gas usually don't occur until a person drinks more than 1 quart a day. Gas can be temporarily increased with bouts of infectious diarrhea.
Gas can also build up behind constipation and can be released in large amounts.
In general, passage of gas causes no symptoms. By age 5 or 6 most children can be taught to release gas in a socially acceptable manner. Gas does not need to be released by inserting anything in the rectum. Air swallowing can be reduced by eliminating some of the habits previously mentioned. Reduced intake of beans and carbonated beverages will decrease gas production in all children.