Is the 5-Second Rule a Myth?

Updated: 2/7/2020

We’ve all done it. You’re preparing a meal in the kitchen and you drop a little bit on the floor. It’s only been in contact with the floor for a few seconds, and you just mopped last week. So you pick up the dropped food and pop it right in your mouth. Surely no harm could come from that….right?

The 5-Second Rule

Many people have adopted a “5-Second Rule” which allows food that has been dropped on the floor to be eaten as long as it’s picked up before five seconds have passed. In fact, a 2003 study by Jillian Clarke, a student at Howard University in Washington, found that 50% of men and 70% of women use the five second rule for food that has been dropped on the floor. But is the five second rule really valid? Is it safe to eat food that has come into contact with the floor, even for only a few seconds?

Many studies have been done on this habit. An in-depth study by the Journal of Applied Microbiology found that bacteria actually adhere to food immediately. This is because of mechanical adhesion, a molecular process that causes dissimilar particles to cling to one another and then spread throughout the surface and lock in place (such as Velcro). This process happens instantly as soon as contact is made, and even if you could pick up your food in one femtosecond (one quadrillionth of a second), it would still be too late.

Time does still play a part, however. The longer the food sits, the more bacteria it will attract. For example, a piece of food that has been on the floor for five seconds attracts anywhere from 150 to 8000 bacteria. However, food that has been in contact with the floor for one minute attracts ten times that. It doesn’t take a lot of bacteria to cause an infection; for example, certain strains of salmonella only require ten bacteria for infection. Of course, your immune system will help to protect against that, but you should still be careful about eating food off the floor, no matter how soon you pick it up.

Even if your floor looks pretty clean, it still contains millions of bacteria. Think about the things that come into contact with your floor, such as shoes. The University of Arizona conducted a study that found that 93% of people’s shoes were contaminated with fecal bacteria – bacteria that will soon be on your food if you drop it on the floor.

Bacteria in Your Mouth

Bacteria are present in your mouth at all times. In fact, if you haven’t brushed your teeth recently, there are more bacteria in your mouth right now than there are people on Earth. That’s a pretty scary thought, especially when you think about how much more bacteria you add by eating food off the floor.

Though your immune system will do its best to fight off the harmful bacteria from infecting you, there are many oral health problems that can occur from bacteria.

• Loss of Tissue: If bacteria gets under your gums, bacteria is able to damage important structures like bone and tissue. It can also spread quickly once it makes its way under the surface, so it’s important to see a dentist quickly if this happens.
• Loss of Teeth: If you don’t get to a dentist quick enough, and the tissue infection spreads to surrounding structures, teeth will become loose and may fall out. If you notice this happening, you should see a dentist immediately.
• Pain: In addition to tissue loss and tooth loss, bacteria can also cause you extreme amounts of pain, specifically while chewing or clenching teeth. If you notice sharp pains in one particular spot while eating, you may have a bacterial infection and should seek dental assistance to prevent further problems.

Other common dental problems, such as oral thrush, gum disease and tooth decay, are also caused by harmful bacteria in the mouth. To prevent problems such as these, be sure to brush and floss regularly, and see a dentist for biannual cleanings. If any problems occur, seek out expert advice immediately. And don’t forget: if the food hits the floor, throw it away!