Double-dipping may seem gross, but it’s not as risky as you think
The question: Is it true that double-dipping can spread germs?
The science:
Like George Costanza on “Seinfield,” many of us have done it — dip a chip into a communal bowl of salsa or stick a veggie into the hummus, bite it and then go for a double-dip.
Yes, double-dipping can transmit bacteria and viruses from your mouth to the shared bowl. And yes, in theory, those microorganisms can be spread to other eaters. But in most cases, that might not be as risky as it seems.
Researchers at Clemson University discovered that there were more bacteria in double-dipped situations compared with the single-dipped. In a series of experiments, the team analyzed how many bacteria were transferred from a bitten cracker into a cup of sterile water compared with an unbitten cracker. They found that if someone had taken a bite before dipping, the water contained significantly more bacteria.
Additionally, the researchers reported that the type of food mattered. After double-dipping, salsa, which has a high acidity, had lower levels of bacteria two hours later than dishes made with cheese and chocolate, which have a low acidity.
While people may be introducing bacteria or viruses into the communal bowl, it does not mean these organisms are the type that can make you sick, said Benjamin Chapman, department head of agricultural and human sciences at North Carolina State University.
Pathogens that cause the common cold, influenza and COVID, for instance, have not been shown to be transmitted through food, Chapman said. Respiratory illnesses such as these are much more commonly spread by coughing and sneezing around people at a party than by eating or drinking after them, he said.
One strong exception is norovirus. Research shows that the virus — which causes the notoriously unpleasant “stomach bug” linked to outbreaks on cruise ships and in other places with close quarters — can be spread through direct contact such as hand-shaking, through contaminated food and water, through aerosols, and, most important to this conversation about double-dipping, through saliva.
“If you are recovering from norovirus, double-dipping would be really risky” for other eaters, Chapman said.
But because “people infected with norovirus get sick very promptly, they're unlikely to spend a whole lot of time during the very brief incubation period sharing a dip with someone else,” said William Schaffner, a professor of infectious diseases and preventive medicine at Vanderbilt University.
There is no real evidence showing that double-dipping can cause foodborne illness outbreaks, though experts said double-dipping often happens in small groups that may not be tracked.
What else you should know:
The double-dipping controversy may be more about social etiquette. “The presumption is, ‘We don’t want to make people sick,’ but really it’s more the ‘ick’ factor than it is the risk of passing a foodborne illness,” said Keith Schneider, a professor in the food science and human nutrition department at the University of Florida.
But here are some best practices, experts said:
• If you are sick, skip the party and protect others from potential illness.
• In any case, wash your hands or, in a pinch, use alcohol-based hand sanitizers before handling food.
• Cover your nose and mouth with your elbow or a tissue when you cough and sneeze. Then wash your hands again.
• If you are the one planning the party, you could consider using individual dishes for dips rather than communal bowls since, theoretically, a person also could spread the norovirus if they accidentally dip a finger or two into a shared snack.
The bottom line:
While double-dipping can spread bacteria and viruses, in most cases, it is unlikely to make you sick, experts said.