The 5 Second Rule is a Myth

The 5 Second Rule is a Myth

Everyone knows the 5 second rule: if you drop food on the ground it is safe to eat as long as you pick it up in less than 5 seconds.

Is it true?

There have been invstigations in the past, the most recent being Is the five-second rule real?

The researchers looked at the transfer of Enterobacter aerogenes from covered stainless steel, ceramic tile, wood or carpet to watermelon, bread, bread and butter, or gummy candy after 1 second, 5, 30 and 300 or seconds of contact.

They did 128 combinations that were replicated 20 times each, resulting in 2,560 measurements.

Wow.  That's devotion.

And the results? Transfer of bacteria varied by surface, contact time, and food type, but bacteria were always transferred instantaneously. The wetter the food and the longer the contact time the more the transfer.

A fun experiment, but really, is it relevant to disease acquisition?  

It depends, of course, on just what the food falls on. The environment is not the source for most infections. Most of the infections we acquire are from each other rather than the environment and most (outside of gastroenteritis) are not acquired from eating. Everything you eat is in contact with some surface from the environment that are not sterile. Unless someone in your house has norovirus or Shigella, there is nothing to worry about.

If you want be entertained and/or disgusted, spend some time watching where people put their hands. They always end up in the mouth, especially around meal time, transferring whatever is in the environment into the mouth.

Years ago I was eating M&M's in the ICU and a couple fell on the floor. I picked them up and ate them, freaking everyone out. But there is nothing in the ICU environment I need to worry about. Later, when we removed the carpet, we cultured a chunk out of curiosity. No pathogens were found.

Sure, I would worry if my watermelon was in contact with, say, a Cipotle bowel for 300 seconds. But otherwise? As long as ants are not hauling off the food on the floor, I don't worry how long the food had been in the floor and even then it adds a nice crunch.

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