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Blowing Out Candles on a Birthday Cake Is Just as Gross as You Think It Is

Dr. Elizabeth Yuko is the Health Editor at SheKnows. She is a bioethicist and writer specializing in sexual and reproductive health and the intersection of bioethics and popular culture. She is an adjunct professor of ethics at Fordham ...

Why you might want to pass on the cake at a children's birthday party

As a small child, I remember attending other children’s birthday parties at our local roller rink or McDonald’s and thinking, “Eww, I don’t want to eat that cake that some other kid essentially just spit on.” Turns out, I was onto something: Blowing out candles on a birthday cake can increase levels of bacteria by 1,400 percent.

Researchers from Clemson University in South Carolina just published a study looking at exactly what happens when someone takes a deep breath and huffs and puffs all over a cake. What I love about their methodology, though, is that before blowing all over a fake cake — a frosting-covered, cake-shaped piece of Styrofoam — the team ate some pizza to truly replicate the conditions of a birthday party. After that, they tested the frosting and compared bacteria levels with another frosted Styrofoam “cake” that did not have candles blown out on it. They found that the post-candle-blow cakes had 15 times more bacteria than the others.

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Of course, not all bacteria are harmful, but if the birthday person does happen to be sick, you might want to opt out of the cake.

More: Don't Ignore These 8 Signs That Your Baby Might Be Sick

Also, it wasn’t part of the study, but based on my own experience attending many, many children’s birthday parties, a lot of younger kids haven’t mastered the technique of blowing air through their lips without picking up some spit along the way. In fact, the cuter (read: younger) the birthday person is, the more chance there is for there to be saliva all over that cake.

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But there are clearly ways around this. There’s no need for the birthday person to spit on the whole cake: Why not just cut it first, plop a candle on one piece, and have them blow that out? Or, take a lesson from parents who may have forgotten to buy birthday-specific candles, and have your child blow out one of the regular candles you keep around your house for when the electricity goes out? What can I say? A candle’s a candle, and your kid will either get over it or write about it publicly 25 years later.

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