An Urban Legend?
An old wives' tale, one repeated even on "Oprah" by Dr. Oz, warned kids not to swallow their chewing gum, because the human digestive takes seven years to digest it. Another version of the myth held that the body cannot digest it at all.
Neither version is true.
The human digestive system usually takes between 6 and 12 hours to completely process whatever we eat. However, chewing gum does resist your digestive system's attempts to dissolve it and break it down. Unlike other foods, chomping gum up between the teeth does not alter its form or mass. If someone swallowed some by accident, he or she would not have to worry about gum hanging out in the stomach for the next seven years or even seven days.
The human body cannot break gum down because gum isn't food. Instead, it's composed of about 15 percent to 30 percent gum base, whether natural or synthetic, which has a rubbery quality that makes it impervious to digestion. To help keep gum soft, some manufacturers add vegetable-oil derivatives; to keep it moist, they use glycerin. Artificial sweeteners such as sorbitol and mannitol, artificial colorings, preservatives, sugar, saccharin or corn syrup round out the rest of gum's content.
Of these components, your body's stomach and intestines can easily break down everything but the gum base. Both natural and synthetic forms of this chemical resist the effects of saliva, stomach acid, and the digestive enzymes secreted by the liver and pancreas. As a result, it gets passed right along to the colon, which turns it into waste for your body to eventually expel.
Length of Digestion
This is where the myth has a bit of truth. The body cannot digest chewing gum, and has to pass it through the digestive system before eliminating it as waste in the same fashion that the body passes through every other food (or non-food) substance swallowed. However, unlike most foods, the gum passes through to the other end largely intact.
In the journal Pediatrics, David Milov wrote of one 4-year-old boy who swallowed five to seven pieces of gum daily and consequently experienced chronic constipation for two years. Doctors had to use suction to remove a "'taffy-like' trail of fecal material" to restore his body to normal digestive health.
However, keep in mind that the child swallowed a large quantity of gum every day for a long period of time and had literally "gummed up" his system at the back end. In reality, chewing gum leads to very few reported cases of gastrointestinal illness. Swallowing a piece of gum accidentally will usually take the digestive system 48 hours to process completely.