Within minutes of eating and even sometimes during a meal, I get very painful cramps and a sudden need to have a bowel movement. It's usually diarrhea. My sister also has this problem. Her doctor mentioned the possibility of "dumping syndrome." Could you explain this syndrome and tell us what can we do about it?

P.

Dumping syndrome is a relatively rare disorder in which the stomach's contents are delivered too quickly to the small intestine. Symptoms include abdominal pain, bloating and dizziness. In addition, people with this syndrome often suffer from low blood sugar, or hypoglycemia, because the rapid "dumping" of food triggers the pancreas to release excessive amounts of insulin into the bloodstream.

Dumping syndrome appears most often following stomach operations, such as ulcer surgery or surgery for severe reflux. Less frequently, it's seen in people born with unusually small stomachs and, even more rarely, in those with no stomach abnormalities at all. In people with no obvious causes, doctors diagnose dumping syndrome by having a patient eat food labeled with radioactive markers and then taking X-ray pictures of his or her stomach to see how quickly it empties. Treatment includes eating smaller, more frequent meals and limiting fluid intake.

That said, I'm not convinced that either you or your sister has dumping syndrome. (I assume that neither of you has undergone stomach surgery since you didn't mention it.)

A more common explanation for your symptoms is something called "gastrocolic reflex." This is a normal response in which the colon contracts after a meal, when the food passes from the stomach into the upper part of the small intestine. In some people, the whole colon is involved in this reflex, triggering diarrhea. In others, only the lower portion of the colon is affected, and a solid bowel movement occurs. There is no specific therapy for gastrocolic reflex . However, some people notice fewer and less severe symptoms if they eat smaller, more frequent meals.

Because gastrocolic reflex may be accentuated in people with irritable bowel syndrome and because diarrhea can be caused by many other conditions, you and your sister should see your doctors for full evaluations.