Talk about a birthday buzzkill.

Blowing out birthday candles causes an astronomical increase in bacteria covering the cake, a new study says.

This is the latest discovery from the same food safety scientists who uncovered the truth about the five-second-rule and other fun germ-y facts guaranteed to validate your inner hypochondriac.

How much more bacteria is spewed across the cake from candle blowers?

We’re talking 1,400 percent more bacteria, on average, compared to icing not blown on, the study says.

Clemson University researchers chronicled these disturbing findings recently in a paper bearing this party-pooper title: “Bacterial Transfer Associated with Blowing Out Candles on a Birthday Cake.”

To measure the epic germ spread, the scientists spread frosting evenly over foil and then inserted candles. They fed their human guinea pigs pizza to recreate the conditions found at a real birthday party. They asked the testers to blow out the candles, and finished by measuring the icing samples’ bacterial counts.

Not surprisingly, the mouth and respiratory tract are full of bacteria, and that bacteria that lands on the cake is “likely” to be eaten by others, the researchers determined. (Unless you’re one of those people who scrapes off the frosting.)

But before you swear off birthday cake, consider that the study’s co-author told the Atlantic that eating a little cake bacteria is not a health concern, so long as the candle blower is not sick.

Still, on your next birthday, maybe think about wishing for this: the power to forget you read this story.

@allieshah