A recent study discovered how blowing candles could spread bacteria and increase it by 1,400 percent.
The frosting on the cakes with candles had way more bacteria than the other cakes.
How hygienic is blowing candles on a birthday cake?
Researchers from Clemson University in SC conducted the study, testing the cake's frosting for bacteria growth, according to the Independent.
The study concluded that, due to the transfer of oral bacteria to icing by blowing out birthday candles, the action of a person blowing onto the cake likely also transfers bacteria and other microorganisms from the person's respiratory tract.
The quirky research included pizza and cake because the scientists wanted to simulate the feeling of a real birthday party. "We thought it might help the salivary glands get going". This is good news, particularly because birthday cake candles are unlikely to stop being lit.
Then they took a deep breath and blew out the candles - they collected frosting and spread it out on agar plates to watch the bacteria grow.
However, the amount of bacteria depended on the force of the blow: The average blow increased bacteria to 14 times that of the other cakes; while other blows increased the bacteria by a staggering 120 times. You avoid the bacteria and the extra sugar. "Some people blow on the cake and they don't transfer any bacteria".
Dr Paul Dawson who led the study explained how he hoped the results wouldn't deter people from blowing out their candles, noting that unless the candle-blower was unwell, it should be harmless.
So it looks like you can have your cake and eat it too. "In reality if you did this 100,000 times, then the chance of getting sick would probably be minimal", Dawson told the Atlantic.