I was pretty surprised when, at a recent dentist’s visit, I was told to start chewing gum to prevent cavities. 

That’s because, my dentist explained, it helps to increase your mouth’s supply of saliva, which is vital for plaque-free teeth.

In fact a 2015 study found that chewing some forms of gum is as good as flossing at removing bacteria from hard-to-reach spots.

The petrol station snack has also been linked to better poop and may even help to get that annoying song out of your head.

Why, then, do some dentists say it’s making your breath worse, or making you hungrier? And crucially, what’s the deal with swallowing gum?

Chewing gum can be good for us ― with caveats

Let’s start with teeth. The American Dental Association (ADA) says that my dentist was right ― it does boost saliva flow, which may reduce the risk of developing cavities. 

But if that gum contains sugar, the risks outweigh the benefits, they add.

Sugar-coated gum can end up giving you bad breath in the long run, UltraDEX’s leading periodontist Dr Rana Al-Falaki, previously told me.

That’s because the sugar on the gum, especially when left in your mouth for a long time, “feeds the bacteria in your mouth that leads to the production of acids, which in turn cause tooth decay and bad breath”.

Don’t worry though, strong minty flavours in sugar-free gum can help offset that.

Mulgrave Dental Group says xylitol is a great sweetener to look out for in gum because bacteria doesn’t feed off it; and the ADA says aspartame, sorbitol, or mannito are good options too.

If you’re looking for the poop-promoting benefits we mentioned earlier, sorbitol, which is a mild laxative, is your best bet, surgeon Dr Karan Rajan says. This is not ideal if you have digestive issues like irritable bowel syndrome (IBS), though.

As for whether chewing gum makes you hungrier, the results seem to suggest not.

A 2013 study found it made no difference to people’s appetites, and while a 2009 study said chewing gum actively stops your sweet cravings and leaves you feeling full, it’s worth noting that research was “supported by a grant from the Wrigley Science Institute”.

What happens if I swallow gum?

I’ll be honest ― I didn’t eat gum until about 14 because I’d been so horrified at the thought of it staying in my body. 

Well, good news: swallowing the odd piece of gum is fine. It should pass through your system within 40 hours and will almost certainly be out within a week.

Still, if you eat an awful lot of gum, especially over a short period of time, you do run the risk of developing a bezoar ― a blockage that leads to constipation, pain, and sometimes vomiting. 

So maybe don’t do that.