Let's get one thing out of the way: Our mouths are positively brimming with bacteria. But as gross as that may seem to some, the vast majority of those bacteria are benign. Still, it may be hard for some to swallow the latest news that blowing out candles on a cake increases the bacteria on that cake 14-fold—even though, "in reality, if you did this 100,000 times, then the chance of getting sick would be very minimal," lead researcher Paul Dawson tells the Atlantic. He and his team also report in the Journal of Food Research that, "for whatever reason," the results vary quite widely from person to person. For instance, some people who blow out candles transfer basically no germs, while others increase the amount of bacteria on the surface of a cake by 120 times.
And at this point, the researchers just can't explain why. One quirky side note: No cake was consumed—or even baked—in the course of the study. As the researchers write, "To test aerosol transfer to cake, icing was spread evenly over foil then birthday candles were placed through the foil into a Styrofoam™ base." But the researchers don't want people to react to their results the way the saliva-scared folks at Romper have; they say the research "just ruined birthday cake forever." The best advice, per the scientists? Relax, enjoy the party, and maybe skip the cake if the person blowing on it is obviously sick. But wouldn't you do that anyway? (Your smartphone has more germs than a toilet handle, by the way.)