How Risky Is Double Dipping?

The practice of double-dipping strikes most people as gross and unsanitary. But does it really increase your risk of infection? Nutrition Diva investigates the science behind the Seinfeld episode.

Monica Reinagel, MS, LD/N, CNS
3-minute read
Episode #362

There are some serious diseases that can be spread through contact with saliva, including pneumonic plague, tuberculosis, and severe acute respiratory syndrome, or SARS—but the chances of running into someone with one of these illnesses at your typical holiday gathering is fairly low. 

Sharing a dip with someone that is double dipping is a little like kissing them.

Your chance of running into someone with a cold, on the other hand, is pretty high at this time of year. And while sharing a dip with a double dipper may be equivalent to kissing them, Professor Ron Eccles of Cardiff University points out that kissing a person who has a cold is not nearly as risky as shaking their hand.

How Do Colds Spread?

The common cold is not spread through saliva but in the mucus, usually via the hands. A sick person blows their nose or coughs into their hand and then shakes your hand, or touches a doorknob or subway pole that you then touch. Just having the virus on your hands won’t necessarily make you sick. It’s when you rub your eyes or nose and transfer that virus to YOUR mucus membranes that you generally get sick.

While Dawson’s study has a certain "ew” factor, it seems to me that the germs that might be transferred to communal food from hands are a bigger concern than bacteria that get transferred from mouths. It’s not just about colds, either. Touching food with unclean hands can contiminate it with bacteria that cause food poisoning as well.

Dr. Dawson had his double-dipping volunteers wear sterile gloves, so his study doesn’t shed any light on what might be transferred from hands to dip even when no double dipping is allowed.

If sharing a dip with a double-dipper is akin to kissing them, I asked Dr. Dawson, is sharing a dip with a single-dipper equivalent to shaking their hand?

“Possibly,” he replied, “if they stick part of the cracker in the dip they have touched with their hands. I hadn’t thought of that. Maybe a new study!”

You heard it here first, folks. In the meantime, maybe the safest thing to do—at least during cold and flu season—is to skip the shared dips altogether, unless fondue forks (or sterile gloves) are involved!

Does double-dipping gross you out? Let me know in the comments below or the Nutrition Diva Facebook page.


About the Author

Monica Reinagel, MS, LD/N, CNS

Monica Reinagel is a board-certified licensed nutritionist, author, and the creator of one of iTunes' most highly ranked health and fitness podcasts. Her advice is regularly featured on the TODAY show, Dr. Oz, NPR, and in the nation's leading newspapers, magazines, and websites. Do you have a nutrition question? Call the Nutrition Diva listener line at 443-961-6206. Your question could be featured on the show.