A healthy living blog from Marshfield Clinic Health System

Drop the five-second rule for fallen food

Illustration - Germs picking up a sandwich - 5 second rule

The five-second rule isn’t a magic number for fallen food. Bacteria can immediately attach to food you drop on the ground.

What do you do when you drop your favorite snack on the floor?

People fall into two groups when it comes to eating dropped food. Those who throw it out, and those who follow the five-second rule, which says it’s okay to eat food off the floor within five seconds because it hasn’t been contaminated yet.

Who’s right?

“Floors can be dirty even though they look clean, and bacteria can attach to food instantly,” said Dr. Alissa Murch, a Marshfield Clinic pediatrician. “It’s best not to eat food that has fallen on the floor.”

Timing, food type and surface matter a little bit

Science fair projects, television shows and researchers have tested the five-second rule and reached the following conclusions:

  • More bacteria attaches to food the longer it’s been on the ground. Although bacteria that can make you sick can attach immediately, food that has been on the ground for a second is safer than food that has been on the ground all day.
  • Moist foods pick up more bacteria. Apple slices and watermelon pick up bacteria more quickly than crackers because moisture makes it easier for bacteria to transfer.
  • Moist surfaces harbor more bacteria. “Most bacteria that cause foodborne illnesses need moisture to live,” Murch said. However, some bacteria and viruses can survive on dry floors.

You should definitely avoid that apple slice that has been on the wet floor for a few minutes, but it’s also a good idea to play it safe and throw away the cracker that just fell.

Don’t panic over an occasional dropped snack

Kids are bound to eat snacks that have fallen on the ground once in a while. It’s usually not a big deal.

“The risk of getting sick from eating food off the floor is fairly low for a child with a healthy immune system,” Murch said.

Monitor your child for signs of illness if he or she has a suppressed immune system. Vomiting, diarrhea, fever and general discomfort are signs of foodborne illness that can start a few hours to a few days after eating contaminated food.

“There is no medicine to prevent illness if your child eats food off the floor, but recognizing symptoms early and contacting your doctor can help if your child has a suppressed immune system,” Murch said.

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