In a world of misinformation, Fitness Pudding is here to separate fact from fallacy, and science from fiction.

Birthday Cake Bacteria


A recent study confirmed that eating a piece of birthday cake that someone has just blown their spit and gooey germs all over, is gross.

The scientists' specific objective was to “evaluate the level of bacterial transfer transferred to the top of a cake when blowing out the candles on a birthday cake.”1 

What they Did

A foil circle was placed on a styrofoam disk. Vanilla icing was spread on top, and adorned with seventeen candles - my guess, to commemorate Samantha Baker’s less dramatic 17th birthday.

Each participant smelled and ate a piece of hot pizza to simulate a meal-and-dessert experience. The candles were then lit, and each participant blew out the candles. The icing was analyzed by counting the number of bacteria colonies formed over 48 hours.

What they Found

“Blowing out candles over icing resulted in 15 times more and statistically higher number of bacteria recovered from icing compared to icing that did not have candles blown out.”1

The maximum transfer of bacteria onto the cake increased 12,000% when the candles were blown out. And that was just on the cake icing, as 90% large bacteria-carrying droplets can remain in the air for 30-minutes, and contain a number of bacteria, as well as viruses. For example:

  • Staphylococcus spp.
  • Streptococcus pneumonia
  • Staphylococcus aureus,
  • Streptococcus spp.
  • Corynebacterium spp.
  • Haemophilus spp.
  • Neisseria spp.
  • Influenza (Flu)
  • Mycobacterium tuberlosis 


Bacteria being spread a birthday cake when the candles are blown out is plausible, especially if the special birthday boy or girl has some special bacteria or viruses to share with the party goers. 

The gift that can keep on giving.


  1. Dawson, P., Han, I., Lynn, D., Lackey, J., Baker, J., & Martinez-Dawson, R. (2017). Bacterial transfer associated with blowing out candles on a birthday cake. Journal of Food Research, 6(4).


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