Raleigh, N.C. ? Maybe this explains why only four out of five dentists recommend sugarless gum to their patients who chew gum:

Turns out the first ingredient in most sugarless gums is a known laxative – sweet-tasting sorbitol. And there’s growing interest among medical providers in harnessing gum’s unintended powers to help patients whose insides are, well, gummed up.

A recent study by University of North Carolina-Chapel Hill researchers found patients who chewed sugarless gum after bladder surgery were able to do their business slightly sooner than those who did not. The digestive tract goes on strike after most abdominal surgeries and it can take up to four days for things to get moving again. In the meantime, many patients suffer uncomfortable swelling, nausea and even vomiting.

The UNC-CH study is just the latest to show off sugarless gum’s potential benefit to blocked-up surgery patients. But prescribing it as preemptive strike against constipation remains a sticky subject.

Dr. Brandon Roy, a general surgeon who practices with WakeMed Faculty Physicians in Raleigh, said some studies have found that gum makes no difference.

Still other studies have linked regular, excessive consumption of sorbitol to chronic diarrhea and dangerous weight loss.

Like that fifth dentist, Roy doesn’t recommend chewing gum to his patients, but would not object if an adventurous soul wanted to give it a whirl.

“I’m an avid gum chewer myself – I love chewing gum,” said Roy, who claims no firsthand knowledge of sugarless gum’s laxative properties. “I couldn’t deny any of my patients that pleasure.”

Casual chompers can relax. The UNC-CH study found patients had to chew about a pack a day for sugarless gum to work its magic.