How many of you get a bit queasy in a Chinese restaurant when you watch everyone dipping and re-dipping into the shared dishes with their own chopsticks? Well, you’re not being a hypochondriac or showing Western cultural insensitivity — there is indeed a major transfer of viruses and bacteria from all that back-and-forth in the dishes. And yes, someone actually studied this; in a 2009 study from Clemson University, some researchers measured the antibiotic levels in chicken broth and rice in multiple scenarios, using spoons, chopsticks and hands. Their results showed a huge load of bacteria in the shared chopsticks & spoons group. Here’s the abstract from their dissertation:
This study examined transfer of bacteria from mouth to different surfaces (spoon, chopstick, hand) and from surfaces to food (chicken broth, rice). Three different sets of experiments were conducted. In the first experiment, bacterial transfer from mouth to utensils (spoon or chopstick) was determined. The second experiment measured bacterial transfer from mouth to broth and included scooping and stirring with a spoon. In the third experiment, bacterial transfer from mouth to food rice was tested using either spoon or hand. Ten or seven subjects were used for each of the three experiments. Results indicated that there was a transfer of approximately 5 log10cfu of total bacteria to the spoon or chopstick when either was placed in the mouth with or without food. Between 4 and 5 log cycles of bacteria were transferred to broth when the spoon was placed in the mouth six times while eating. Approximately 1 million bacteria were transferred each time from mouth to rice by using hands. More than 5 log cycles were transferred to the rice when the spoon was used to consume the rice then placed back in the bowl for 5 cycles. There were high numbers of bacteria transferred to the common bowl of rice when a spoon was used however much lower number than when the hand was used. The overall conclusion was that significant bacterial transfer from mouth to utensils (spoon or chopstick) and from mouth to food occurred when utensils or hands were placed back into food after consumption.
Other research has also suggested that such sharing of utensils is a common cause of spreading infections such as H pylori, hepatitis, and simple colds and flu, as well as many gastroenteritis bacteria. For example, one study in Melbourne showed evidence of transmission of H pylori in Chinese immigrants via chopsticks, commenting in the abstract that “this study suggests person-to-person transmission of H. pylori via the oral-oral route with ethno-specific food practices an important risk factor.”
Another study, from Hong Kong, in 2005 found a high prevalence of H pylori in children and concluded that “H pylori has a high prevalence in Chinese children with increasing age. Eradication efforts seem to be unsuccessful in the reduction of prevalence. We hypothesize that this may be owing to cross-infection at meal times from sharing chopsticks.”
So What To Do?
Well, that’s a major, major question, isn’t it? I think it would be rude in most circumstances to make a fuss at a large dinner gathering, especially if you’re a guest. But no matter what, the risk is there, so perhaps with much public education, many more restaurants will automatically supply extra chopsticks or spoons with the common dishes. All the high-end restaurants already do this; a major public health breakthrough would require such practices spreading to the far more numerous medium and small restaurants.
In the meantime, certainly at home you should take control and provide each dish with separate utensils. Also, you could also start carrying around and using your own metal chopsticks. I got a pair at Muji and use it at work every day. No, I never got the courage to bring a second pair to restaurants, but it’s not a bad idea at all, especially as a way to cut down on disposable chopstick use.