What's a birthday party without the traditional blowing out of the candles on the cake? It's a ritual that has marked birthday celebrations since time began and in the course of a lifetime, most of us would have partaken in the eating of many slices of birthday cake that have been blown on in this fashion.
However, you might want to think twice before saying yes to your next piece, with research showing that a cake becomes ridden with bacteria following a good candle-blowing.
The study was conducted by researchers at Clemson University in South Carolina, who found that the saliva spread from blowing out birthday candles increases bacteria in the icing by 1400 per cent.
According to the Daily Mail, Dr Paul Dawson, a professor at the university, conducted the study with a group of his undergraduate students to get them thinking about food safety.
He is known for looking into food and hygiene issues like the five-second rule and the risks of sharing food, and made headlines in 2015 for warning people against double dipping (it can spread infectious diseases).
The team had turns blowing out candles on a piece of icing that they laid over foil, atop a Styrofoam wheel, and then counted the bacteria by diluting the icing with sterilised water and spreading it on to agar plates for the bacteria to grow.
On average, blowing out the candles caused the icing to grow 14 times as much bacteria. In one case, the amount of bacteria increased by more than 120 times, suggesting certain people transfer more bacteria than others. Interestingly, each blow also resulted in different types of bacteria. Human mouths are actually full of bacteria, but most of them are not harmful.
While the thought of all this may make you feel a little bit sick, Dr Dawson told the Daily Mail he doesn't think this should put people off eating birthday cake.
"In my opinion, you're fine to eat a birthday cake if someone blew out the candles," he explained. "I don't think you'd get sick."
Well, unless the candle blower was under the weather- maybe err on the side of caution if they look a little peaky.