While tempting, it's best to not eat food that fell on the floor. Image: MARTINS RUDZITIS / Getty Images

Since elementary school, we’ve all been taught the “5-Second Rule.” The idea is simple: Food dropped on the floor is still perfectly edible if retrieved in under five seconds. The logic behind the theory, such as it is, is that germs and dirt and pet dander are somehow caught by surprise by the sudden arrival of food and need a few seconds to get their bearings. If you snatch the food up quick enough, they won’t have time to get it “dirty.”

Even as kids, we were skeptical but admit it–you still roll the dice on it every now and again. It’s like shouting “shotgun” before getting into the passenger seat even if it’s only you and the driver. It’s instinctual. But is it true?

“Let’s go with ‘No,’ there is no truth to the ‘5-second rule’,” says Gillson Sciences Director of Operations Erin Thane.…