As a kid, you had probably heard the phrase that too much candy would cause your teeth to rot, and nothing was worse then that one guy who always passed out toothbrushes on Halloween.

But perhaps that guy wasn’t too far off.  The Science of Cooking website called attention to this:

“Today we know that the real problem isn’t so much sugar, but the streptococcus bacteria in our mouths that like to feed on it,” the site said. When they feed on the sweet treats lodged in your teeth, they excrete acids that eat away at your tooth enamel.”

While the bacterium is found naturally in your mouth, other bacteria present in the mouth and your immune system keep everything balanced.  Overgrowths of any naturally-occurring bacteria can cause some major problems.

“Streptococcus pyogenes, often referred to as group A streptococcus bacteria, can cause rheumatic fever, impetigo, scarlet fever, puerperal fever, streptococcal toxic shock syndrome, strep throat, tonsillitis and other respiratory infections,” said the Encyclopedia Britannica’s website. It goes on to explain that group B Streptococcus bacteria can cause meningitis, sepsis, and pneumonia.

While you’re not going to get a severe infection from eating candy, you should know what it is that decays your teeth. Not the sugar, but the bacteria.