Does this look familiar? You’re enjoying a snack, and suddenly a piece breaks and lands right on the floor: the 5-second rule countdown starts.
Do you pick it up and dust it off, trusting the rule?
Or does it go straight in the trash?
This week I’m going to get through it. Ready to be amazed?
Many of us rely on the 5-second rule (or its stricter 3-second cousin) to decide the fate of food that touches the floor (or any other surface).
But where does this rule come from, and is it actually safe?
The Curious Origin of the 5-Second Rule
The origin of the 5-second rule is shrouded in mystery, with some theories suggesting it dates back to Genghis Khan’s era.
Apparently, during his conquests, a “Khan rule” existed for banquets. Food that fell on the floor could stay there as long as he permitted it, the idea was that “food prepared for Khan was so special that it would be good for anyone to eat no matter what.” [Source]
Most likely it was simply due to the fact that bacteria are invisible so as long as the visible dirt was removed, food was considered good to go.
While this historical anecdote is quite entertaining, science is our best guide for food safety. Studies on the 5-second rule have yielded mixed results, with some methodologies raising quite some questions about their accuracy.
However, a peer-reviewed study published in the Journal of Applied Microbiology sheds some light on the debate [Source].
Exposure time significantly impacts the number of microorganisms transferred to food upon contact with the floor.
This research was expanded in 2016, testing various food types and floor surfaces. The results?
- Watermelon picked up the most bacteria regardless of the floor.
- Gummy worms were the least hospitable to microbes.
- Longer contact with the floor meant more bacterial contamination, with moisture playing a key role.
Here’s a surprising twist: carpet flooring emerged as one of the safer surfaces for fallen food! The tight fibers and reduced surface contact might explain this unexpected outcome.
One big point to have very clear from the study
Although they found that longer contact times result in more transfer, they also found that other factors, including the nature of the food and the surface, are of equal or greater importance. Some transfer takes place “instantaneously,” at times of <1 s, disproving the 5-second rule.
To Eat or Not to Eat: that is the question
So, what does this all mean for the 5-second rule and your health?
Here’s the truth:
there’s no guarantee that a quick floor pickup won’t introduce harmful bacteria.
Over a lifetime, occasional ingestion of floor-kissed food might not have bad consequences. However, it’s a gamble for you to decide to bet on.
Consider these factors when making your decision:
- Food Type: Wet, moist foods like watermelon are best thrown away. Drier options like crackers might be ok (or not, you choose).
- Location: Food dropped in your clean kitchen is a different story compared to a public restroom floor (duh). In the latter case – and I don’t think I need to write it here – throw it away!
- Material of the surface it falls on: varying surface topography (how rough or smooth a surface is on a microscopic level) can influence the amount of bacteria that accumulates inside.
- Pets: If pets roam freely indoors, their tracked-in microbes add another layer of risk. Most likely trash is the best option. After all pets that go outside bring bacteria back home and even if they don’t go out, they still lick their butthole and then their paws and they walk all over your house.
Last time I checked, no good bacteria comes from an anus, don’t know about you but I’d throw everything away.
A Bite of Reality: the 5-Second and friends
The 5-second rule isn’t the only scenario where food encounters questionable surfaces. Here are some interesting bonus situations for you to be…well, re-thinking things:
- Birthday Cake Wishes: Blowing out candles showers the cake with bacteria from the celebrant’s mouth. It’s up to you to decide to eat the cake…or not.
- Double Dipping: Sharing guacamole with friends involves some bacterial exchange. Again, it boils down to your personal comfort. As a personal rule, double dipping while with a group of friends is a d*ck move but who am I to say.
- Wait, what about flies? Well, where do you most likely find those black flies hanging out on? Yep, poop. Do you think flies wash their hands before landing on your food to bother you? Again, up to you on what to do about it!
There I ruined it.
Ultimately, the choice is yours. Now that you know you can’t un-know so congratulations!
You’re now fully able to make informed decisions about whether to share guacamole on a date, a slice of an extra seasoned cake or to eat anything that falls out of your plate on any surface.
You’re welcome!
