Have you dropped a piece of food on the floor and picked it up proclaiming the “five second rule”? As a registered dietitian, I’ve heard everything from the “five second rule” to the “one minute rule.” But is food really safe to eat after it has been in the ground for some time? Here’s what you need to know about the five-second rule.
To most people, “clean” means that something is free of visible dirt. However, even though your floor may Appear to be clean, you can still have a lot of invisible microorganisms. Most household floor cleaners will kill most harmful germs for a while, but certain bacteria and viruses (such as norovirus ) can still survive on surfaces for months. If you’re thinking you can “cook it” by heating food before eating it, it’s important to know that some pathogens can survive in very hot and very cold temperatures.
There have been several studies examining the “five second rule” that reveal slightly different results. A 2014 study at the School of Life and Health Sciences at Aston University in Birmingham, England, says the 5-second rule is actually true. The study monitored the transfer of common bacteria Escherichia coli (E. coli) and Staphylococcus aureus from a variety of interior floor types (carpet, laminate, and tile surfaces). Observed toast, pasta, cookies, and sticky candy when contact was made with the floor for 3 to 30 seconds. The results showed that time and floor type were significant factors in the transfer of bacteria from the floor surface to a food. This study found that bacteria are less likely to transfer from a carpeted surface compared to a laminate or tiled surface when wet foods are in contact with them for more than five seconds.
So does this study show that it’s okay to drop food on the floor for 5 seconds? Not quite. The research concluded that you are still at risk when you eat food that falls on the ground due to bacteria that could be lurking.
A 2016 study in the journal of the American Society for Microbiology, Applied and Environmental Microbiology disproved the five-second rule. The researchers looked at what happens when you drop a variety of foods, including watermelon, bread, buttered bread and jelly beans, onto four different surfaces. Surfaces included carpet, stainless steel, ceramic tile, and wood. The foods were dropped and left on each surface for one second, five seconds, 30 seconds, and 300 seconds. Each possible scenario (a total of 128!) was repeated 20 times.
The results showed that the watermelon became the most germ-ridden, even for a short time on the floor, and the jelly beans picked up the fewest contaminants. The bread and bread and butter were in the middle for germ levels. What the data did reveal is that the longer the food sat in the soil, the more bacteria it picked up. However, even if the food remained on the ground for only a few seconds, it was not bacteria-free, disproving the alleged five-second rule.
Although you may not always get sick after eating off the ground, it’s not the wisest decision. The very young and the very old have weaker immune systems and are more susceptible to disease, so it is especially important not to teach this habit to children. Yes, the faster you pick up the food, the less bacteria are likely to build up. However, it only takes one time to spot the wrong bacteria or too many bacteria that can make you sick.
*This article was written and/or reviewed by an independent registered dietitian nutritionist.