The Five-Second Rule

Is it OK to eat food that has been dropped on the floor, so long as it is picked up within five seconds? Here at MSN Health & Fitness we’re interested in, well, your health and fitness—so the short answer is no, the food should be tossed. But you knew that already.

Informal studies discredit the rule.

In 2003, high-school student Jillian Clarke garnered media attention for work she conducted during an internship. In her study, Clarke spread E. coli bacteria on ceramic tiles, then placed pieces of fudge-striped cookies and Gummy Bears on the tiles. In all cases, the E. coli microorganisms were transferred from the tile to the food in five seconds or less. Even more of the bacteria were transferred to the Gummy Bears from smooth tiles than from rough tiles, probably due to more surface-to-surface contact. Clarke’s studies earned her an “Ig Nobel” prize, but all her friends stopped asking her to butter their toast.

In an episode aired in October 2005, the crew of television’s MythBusters (Discovery Channel) found just as much bacteria after two seconds as on food left for six seconds.

As you may have guessed, there’s not a great deal of credible scientific study dedicated to the issue.

Germs don’t just blow away.

If you do opt to consume that fumbled Tastykake, don’t fool yourself into thinking you can sanitize the thing by brushing it off or blowing away the germs. (We’ll leave it up to the faithful to judge the value of “kissing it up to the sky,” the Hail Mary of food rescue.) Germs are tenacious and hard to kill, which is why it takes at least 15 seconds to wash our hands well and 155-degree heat in a dishwasher to sanitize a drinking glass.

Your immune response has got your back.

For some, the issue is, How much bacteria might now be on that cookie, and does it have the potential to make me sick? For others, the question is, Was that really the last Oreo? Our bodies are designed to protect us when common sense does not, within reason; saliva and stomach acid fight infection, and the natural responses of a healthy immune system will protect most people against a minor germ incursion. No doubt more people get sick from undercooked meat—or ingest more germs biting their fingernails—than from a dash of floor spice. The risk to bottom-feeders increases, though, when the immune system is compromised and/or the microorganisms transferred are more pathogenic (that is, likely to cause disease).

The chance of getting sick depends on variables of food and floor.

Dr. Philip Tierno, known as the King of Germs at New York University, estimates that 50 percent to 80 percent of all food-borne illnesses are contracted in the home. He says the kitchen is the dirtiest room even in the cleanest house. There’s no telling what pathogens may have been brought in with the last batch of groceries or what may have been tracked in on the soles of a family’s shoes. (Do you have pets? What have they been walking in?)

If a hard pretzel hits a dry, clean floor at home and you eat it anyway, we do expect you to survive. As you might guess, the transfer of microorganisms increases when something sticky like a syrup-soaked piece of pancake makes contact with a more absorbent surface like a shag rug. It’s the risk inherent in unknown factors that should signal a warning sign. Eat a stray jalapeño from under the table at Taco Bell and you’re on your own.

The five-second rule wasn’t invented for the person eating; it was made up for witnesses.

The rule is an excuse, probably improvised by a hungry kid who dropped the last doughnut when his friends were watching. When you invoke the five-second rule, do you really figure the food was magically sealed for five seconds, or are you asking one-time permission to eat off the floor?

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