Aside from the threat of getting spit on the icing (ewwww), according to a recent study, blowing out candles on a cake can increase the number of bacteria on said cake by 1,400 per cent.
To conduct the experiment, subjects were asked to consume pizza and then blow out candles over a fake cake covered in icing.
One, the agar plate method isn't the most precise way to count bacteria as they don't all grow well on them.
The frosting on the cakes with candles had way more bacteria than the other cakes.
Upon testing the icing retrieved from the cake, researchers found that the frosting had the increased amount of bacteria as compared to icing that had not been blown on. "We also wanted to simulate a birthday party", said Dawson.
Maybe it's best to just not think about it and to keep on eating cake the way we have for decades.
And the variation of bacteria was 100 times greater on cakes that had candles that had been blown out - that's more than 100 different types of bacteria.
And in one terrible case, the number of bacteria increased more than 120 times - suggesting that some of us transfer more germs than others. He added that it would be common sense to avoid a slice from a cake on which a clearly sick person had blow on to.
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.
"It's not a big health concern in my perspective", Dawson told the Atlantic. This means you can have your cake and eat it too.