Walk down any well-travelled sidewalk, and you'll see the flattened remains of chewing gum as dark splotches on the pavement. Reach cautiously - beneath the desks in any school classroom and you'll find rubbery hunks of A.B.C. (already-been-chewed) gum.

Gum is everywhere and seems to be always within reach at convenience stores and in the checkout aisles of supermarkets. Canadians spent an estimated $507 million on chewing gum in 2014. If a stick of gum costs about 11 cents, that means Canadians chewed about 4.6 billion sticks of gum in one year. That's 131 sticks of gum per year for each Canadian!

What are we all chewing on anyway?

The thing about gum is that you can chew and chew and chew it, and it won't break down. That's because of an indigestible, rubbery substance called gum base. The origins of modern chewing gum's base can be found in the resin of trees. This was replaced by paraffin wax for awhile. Then came chicle, a type of sap from the sapodilla tree of Mexico and Central America. Chicle was eventually swapped out for cheaper synthetic materials.

In addition to the natural and artificial flavours that have long been added to the gum base, we're also chewing on a number of other ingredients. Vegetable oils make gum softer, while glycerin helps gum maintain its moisture. Colourings and preservatives find their way into gum, and sugar, mint, or other flavourings add taste to the rubbery texture. Sugarless gums use sweeteners like aspartame.

Xylitol, mannitol, and sorbitol are natural sugars often used in "sugarless" gums because they cannot be broken down by the bacteria in our mouths. If they can't be broken down, they can't create the acid that would damage the teeth.

If gum is indigestible, is it dangerous to swallow?

Most of us have swallowed a piece of gum at one time or another, right? Afraid you'd be caught by a teacher or by a boss during a meeting, you gulp down the little wad and hope it's all right. Or maybe it happens by accident when you laugh or cough. But what happens when you swallow gum? Does it stick to your intestines or muck up your insides?

Calling gum "indigestible" is a little misleading. The flavourings, preservatives, sugars, and calories are all digested normally. It is true that our bodies can't break down the gum base part of gum, but it still gets moved right along through - and out of - the body at the normal pace, like the way fibre does. It just won't be changed too much by the trip through intestines!

Unless you chew and swallow many, many pieces of gum at one time, you don't have much to worry about. The gum loses its "stickiness" once it's in your body, but swallowed gum can very rarely cause a digestive blockage and constipation. In rare cases when kids experience constipation, swallowed gum may be to blame. On the other hand, if you chew too much gum with xylitol, you may experience a laxative effect.

So, swallowing gum won't hurt you - but is gum bad for you otherwise?

The folks who make gum want you to chew and chew, so they strive to make their gum's flavours last longer and longer. All this champing could cause a sore jaw. Some ads even joke about this, but overly-stressed jaw muscles may trigger a painful condition called temporomandibular joint dysfunction, or TMJ. If you start to notice tension or pain in your jaw, take a break from gum.

Concern about one of the most common chewing gum dangers prompted the creation of a whole new kind of gum - sugarless gum. When you're chewing gum, sugars release onto your teeth and cause tooth decay and cavities.

Spending too much time chomping could also mean that you're gulping in extra air. Extra air creates gas, which can cause belching and bloating. The sorbitol added to some sugarless gums has been known to make gas worse, too.

Gum doesn't seem too bad for you. Could it actually be good for you?

Our ancient ancestors chomped on the rubbery sap to fend off thirst, clean the teeth, and freshen their breath. Birch bark tar found on an archaeological dig in Finland is actually suspected to have had antiseptic power against gum infections.

Not much has changed. People still chew gum to quench thirst or moisten a dry mouth. Gum also comes in handy to release ear pressure due to altitude changes during air travel. Gum additives like magnolia bark extract can act like antibacterial bad-breath fighters. Sugarless gum that was once only a more tooth-friendly alternative to regular gum may actually help to prevent cavities.

Another thing that damages the teeth - acid - may also be neutralized by chewing gum. When we chew our food, it gets broken down and the acid from this process can erode the enamel of teeth. By chewing sugarless gum for half an hour after a meal, acid gets cleared away, protecting the teeth and reducing the risk of heartburn from acid reflux.

People who frequently get heartburn may have tried antacid gums. That's an example of so-called "functional" gums, which release medicinal or therapeutic ingredients into the body. They're a natural way to administer nicotine to people trying to quit smoking, or tooth whitening agents to those seeking a superstar smile. Another type of gum, "fortified" gum, contains added ingredients such as vitamins, probiotics, or antioxidants that are meant to keep you healthy, like the way fortified milk contains added vitamin D.

So, the bottom line is that for most people, chewing gum is not bad for you. In fact, the Canadian Dental Association provides a seal of recognition for some products that contribute to dental health. Just make sure the gum you chomp on is sugarless.

Amy Toffelmire