Following recently published research that suggests that repeatedly boiling hot-pot broth results in harmful levels of nitrite, specialists recommended that hot-pot lovers finish their hot-pot broth as soon as possible during the first 30-minute round of boiling.
In an article appeared in the Shanghai Journal of Preventive Medicine, four different flavors of hot-pot broth were tested for nitrite levels after 30, 60 and 90 minutes of boiling. After 90 minutes of boiling, the nitrite level of pickled cabbage hot-pot broth spiked almost 10-fold (9.83) to 15.73mg/L, that of seafood hot-pot increased 7.06 times to 12.70mg/L, double-sided hot-pot 3.05 times and bone-based hot-pot broth 2.88 times (with original nitrite levels of between 1.3 and 1.8mg/L), the research showed.
Linkou Chang Gung Memorial Hospital department of toxicology director Lin Chieh-liang (林杰樑) said that nitrite was a chemical element often found in fermented food, but there is little research on the increased levels of nitrite after continuous heating.
He said he believed the research was particularly valuable for the hot-pot and soup-obsessed Taiwanese.
Lin said that an excessive intake of nitrite can cause methemoglobinemia, a blood disorder with symptoms including headache and shortness of breath due to lack of oxygen.
A serious case of methemoglobinemia can be fatal.
The acceptable daily intake of nitrite per 10kg of body weight is 0.73mg/L, Lin said.
That means that a 60kg adult with an acceptable daily intake of 4.3mg/L can easily exceed the recommended amount of nitrite after only a few bowls of 90-minute-boiled, pickled cabbage hot-pot soup.