The five-second rule has always had your back — in theory. You drop a cookie, a sandwich, or whatever other snack and race to pick it up. So long as you shout “Five-second rule!” the questionable hygiene of your decision is excused, and you’re free to chow down on your recovered snack. But is your food actually safe to eat once you pick it up?[related]
The rule itself certainly didn’t originate from any semblance of scientific inquiry. More likely, someone just really wanted to eat some morsel they dropped on the floor and spurted out “Five-second rule!” before gleefully popping it in their mouth. But the folk belief has spurred a number of research attempts to either validate or disprove the mantra — and the results are mixed.
According to a study from 2016, food does get dirtier the longer it’s on the floor. However, a good amount of bacteria globs onto the food as soon as it hits the ground. So your food isn’t necessarily safe at any point after you’ve dropped it — but it could get worse after that fabled five-second window.
The same study also revealed that certain foods cling to more bacteria than others. As you might expect, a piece of watermelon or a glob of jam are more likely to pick up bacteria than a dry food, such as a cracker or slice of bread. Wet food could be more risky to recover. Additionally, the study found that carpeted floors transferred fewer bacteria than tile or stainless steel, so the texture of the surface also plays a role.
Another study in 2017 showed that though bacteria can latch onto food instantaneously, food that’s quickly retrieved might not be as gross as you think.
“Obviously, food covered in visible dirt shouldn’t be eaten,” conceded lead researcher Anthony Hilton, “but as long as it’s not obviously contaminated, the science shows that food is unlikely to have picked up harmful bacteria from a few seconds spent on an indoor floor.” Eating something that’s suffered a quick drop probably won’t kill you.
So is the five-second rule true? Kind of.
Next time you fumble, use your best judgement. If you haven’t cleaned your floors in a week, you might want to pass. But if the surface was clean, or maybe even carpeted, there’s a good chance your food won’t make you sick. These foods, on the other hand, could kill you — no matter if you dropped them on the floor or not.