New science on the “five second rule”

Everybody does it. Well, at least 87 percent of people admit to doing it: eating food that has been dropped onto the floor. That is one of the findings in a new study on the transmission of bacteria to food conducted by students at Aston University in Birmingham, U.K. The study offers a bit of support to the longstanding “five second rule” that many people invoke when it comes to dropped food. The study found that the longer food rests on the floor, the more bacteria will hop on to it. This contradicts a finding by the hosts of the television show Mythbusters.

However, both this study and the Mythbusters agree that the type of food and floor surface play significant roles in determining how much bacteria is transmitted. Wet or sticky foods (the students tested toast, pasta, biscuit, and a sticky sweet) picked up more bacteria, but surprisingly, carpet transferred far fewer bacteria to food than hard surfaces like tile or linoleum. Professor Anthony Hilton, who oversaw the study, noted that “We have found evidence that transfer from indoor flooring surfaces is incredibly poor with carpet actually posing the lowest risk of bacterial transfer onto dropped food.”

While eating food off the floor still carries a risk that you will pick up infectious bacteria, people can take some solace that following the five second rule enjoys a bit of supporting science. Will these findings change your mind about eating dropped food?