As kids, we’re often told not to pick food up from the floor. Once it’s dropped, it’s dirty. Not good for eating. Yet we still do it — kissing it and holding it up to the sky. Then, a few years later we learn about the five-second rule. If it’s dropped, pick it up quick, and you’ll still be able to eat that last delectable cookie. If you do this, you’re not alone. Eighty-seven percent of people in a new study said they would eat food dropped on the floor, and it wouldn’t necessarily be bad for them, as the five-second rule could actually be real.
There’s a good reason for why people might be apprehensive about eating food off the floor. The floor is dirty, to put it simply. Its bacterial contaminants include Staphylococcus aureus (S. aureus), Salmonella, and Escherichia coli (E. coli), which are common causes of gastrointestinal infection due to the toxins they release inside the body. These infections are mostly characterized by nausea, stomach cramps, vomiting, and diarrhea.
Looking to see if the five-second rule is scientifically true, researchers from the Aston University School of Life and Health Sciences looked at how fast S. aureas and E. coli transferred from floor to food. For between three and 30 seconds, they tested toast, pasta, biscuits, and a sticky dessert on a variety of floor surfaces, including carpet, laminate, and tile. As expected, they found that the longer a piece of food was on the floor, the more likely it was to pick up bacteria. But they also found that the amount of bacteria transferred depended on the kind of floor it dropped on. Bacteria transferred slower on carpeting than on tiled and laminated surfaces.
“Consuming food dropped on the floor still carries an infection risk as it very much depends on which bacteria are present on the floor at the time; however the findings of this study will bring some light relief to those who have been employing the five-second rule for years, despite a general consensus that it is purely myth,” said Anthony Hilton, a professor of microbiology at the university, in a press release.
When it comes to E. coli, the findings are pretty reassuring. Most types of E. coli are harmless, according to the National Institutes of Health, and that’s partially because they already live in our intestines. However, people with weakened immune systems or older adults and young children could be at a higher risk.
While E. coli may be relatively harmless, S. aureus can be far more dangerous, because some of them are antibiotic-resistant. They’re part of a growing population of “superbugs” that have adapted to antibiotics, allowing them to persevere and continue to infect. In September, the Centers for Disease Control and Prevention released a report on antibiotic resistance, in which it labeled methicillin-resistant S. aureus (MRSA) a serious threat — one level beneath the most threatening. MRSA is most populous in hospital settings. However, reports have also found them throughout industrial farms, where antibiotic use is also high.
So, although it’s not necessarily harmful to eat food you dropped on the floor, there is a risk. Five seconds may buy you some time with bacteria — though not very much, if any — but do you really want to pick up food that might also have dirt, hair, and other filth on it?