The Five-Second Rule: Fact or Fiction?

Five Second Rule

We’ve all done it: Yelled “5-second rule!” after dropping food on the floor, then quickly picked it up and popped it into our mouths. The as­sumption is that 5 seconds is not a long enough time for the food to pick up harmful bacteria.

Or, is it?

A high school student doing an apprenticeship in a University of Illinois laboratory decided to test the validity of the 5-second rule. She took swab samples from floors around campus to determine bacteria counts. The floors were surprisingly clean.

Next, she inoculated rough and smooth floor tiles with E. coli bacteria. She placed gummy bears and fudge-stripe cookies on the inoculated tiles for 5 seconds, then examined the foods under a high-power microscope.


Her findings showed that in all cases, E. coli was transferred from the tile to the food, demon­strating that microorganisms can move from ceramic tile to food in 5 seconds or less. Clarke found that more E. coli was transferred from smooth tiles than from rough tiles and that both the dry cookies and the gummy bears be­came contaminated from only 5 seconds of con­tact with the inoculated tiles.


So, the next time some yummy morsel falls to the floor, resist the temptation to pick it up quickly and eat it. We know it’s hard, but just trash it.



The 2011 Old Farmer's Almanac

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5-Second Rule

I have indeed applied the 5-second rule on many occasions in my own residence and, in my 68 years, never gotten ill from it. However, I don't do it in public places, nor do I go around the house inoculating my floors with e-coli, so that could have something to do with it. I've also seen studies that conclude foods with high salt or sugar content are more immune to contamination. In my opinion, a certain amount of contamination keeps our immune systems strong and, therefore, us healthy. I think that hand sanitizers were invented by people with OCD.