What Really Happens to Swallowed Gum?

Posted by Eric Troy on 10 Feb 2014 15:35

When I was a child, in the 1970's, we were told that if we swallowed our chewing gum, it would remain in our stomach for seven years. In colloquial terms, this means that people thought that it takes seven years to digest a piece of chewing gum. This belief had probably been around from before I was born, and may have existed since chewing gum became widely available. It is, of course, a myth, but the source of it is unknown. There is a kernel of truth, as in most myths. Most of what makes up chewing gum is completely indigestible.

Early gums were made of chicle, the natural resin from the sapodilla tree, or even paraffin wax. Today's gums are made of latex, resins, and waxes. If these materials just hung around in your gastrointestinal tract, it is true that it would take a long time to digest them. In fact, it would take longer than seven years as they are completely indigestible. Whether some natural process of degradation might occur that would eventually break down the gum is not something we can know. Neither is this the point.

Because gum doesn't just hang around in your gut waiting for your body to fail to digest it, plugging up the works (well…maybe, I'll get to that), and generally making a mess of things. What happens to gum is what happens to anything that doesn't get stuck (don't swallow sharp objects). It passes through the gut, into the rectum, and out with the stool. This takes one or two days. Remember, the occasionally swallowed piece of gum is not the only indigestible thing we consume. The fiber in vegetable foods cannot be digested either. And sometimes food that is digestible passes through the gut too quickly to be fully digested. No matter, it all comes out the other end.

However, most of us only swallow a piece of gum occasionally, and usually by accident. We can pretty much rest assured that this is harmless. But I would advise you not to test fate. To understand why I would give that advice, you only need to read this collection of case studies from David E. Milov, et al., entitled Chewing Gum Bezoars of the Gastrointestinal Tract.1 A bezoar is a mass of foreign material that gets trapped in the gastrointestinal system. Usually, the material is hair (as in "Rapunzel Syndrome") or fiber and other materials, and these masses are usually in the stomach. The word bezoar comes from Persian, and it means "antidote." It was once thought that bezoars were powerful antidotes to poison.

The first case describes a 4 1/2 year old boy with a two year history of constipation. During toilet training, gum or candy was often given as a reward for a successful potty. Everything seemed normal on examination but a firm fecal mass was palpated in the rectum. Treatment was attempted with fiber supplements, saline enemas, and mineral oil, but after four days, there were no results. The doctors had to manually remove the impacted stool, called a fecoma.

On removal of the leading edge of the fecoma, a "taffy-like" trail of fecal material remained in the rectum. This mass was eventually manually withdrawn and was primarily made up of chewing gum. On further history, this boy always swallowed his gum after chewing five to seven pieces of gum each day…

The second case report is similar, and the third involved a 1 1/2 year old who had a mass of gum and coins (dimes and pennies) stuck in her esophagus. One and a half years is too young for gum, and toddlers occasionally swallow small objects. However, you should be able to see the writing on the wall. There is a such thing as swallowing too much gum! In the first case, it is true that the constipation episodes seem to have begun before gum started to be given to the child, however, it could be that this constipation was itself part of the reason the gum formed a bezoar. According to the report:

Our report adds to an already long list of adverse health effects from chewing gum. Two patients, each toddlers, received gum on a daily basis and their means of discarding the gum (swallowing) was well known to the families and was a source of levity. Each child presented with intractable, medically refractory constipation that required manual stool removal. Interestingly, the disimpaction procedure is characteristically a "taffy-pull." The rainbow of fused, multicolored gum fragments in the removed fecoma is easily recognized by physician and family as old gum. It is assumed that the third patient, an infant, put multiple coins in her mouth at a time when she was chewing gum…

The authors also note that other authors have previously reported similar gum removals to relieve symptoms. It seems clear that gum should not be given to children, at least frequently, that do not understand that it should not be swallowed or that are not yet able to chew gum without swallowing it. As a reward for potty training, fully digestible candy or other snacks might be better. Regardless of these cases, you don't need to worry if you, or your child, occasionally swallows a piece of gum. These kids were swallowing up to seven pieces of gum a day.

1. Milov, D. E., J. M. Andres, N. A. Erhart, and D. J. Bailey. "Chewing Gum Bezoars of the Gastrointestinal Tract." Pediatrics 102.2 (1998): E22.
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