Many people have heard that hot pot soup should not be consumed because it contains toxic substances. Some friends ask, when is it not drinkable? Is the freshly boiled soup undrinkable too? Can none of the soup boiled for a long time be consumed?
The key to this question lies in data. I found a domestic research paper that measured the changes in nitrite content in 24 pots of four types of hot pot soup. Data was collected at four points: at the beginning of the meal, and 30, 60, and 90 minutes after cooking various foods.
The test results found that as the cooking time extended, the nitrite content in the hot pot soup did indeed continuously rise. By the end of the 90-minute meal, the sour cabbage broth showed the highest increase, at 9.83 times, followed by the seafood broth at a relatively high 7.06 times. The increase in the bone broth and the yinyang broth was smaller, at 2.88 and 3.05 times, respectively.
In terms of nitrite content, the initial concentration of the broths was not significantly different, ranging from 1.3 to 1.8 mg/L. However, as the hot pot cooking time lengthened, the difference in nitrite content became more pronounced. The final nitrite content in the sour cabbage broth was as high as 15.73 mg/L, and the seafood broth reached 12.70 mg/L. Therefore, the statement that hot pot soup cooked for too long is unhealthy is well-founded.
However, if one drinks such soup, will it cause nitrite poisoning? Based on the highest concentration of 15 mg/L, drinking two small bowls (400ml) of soup would result in an intake of 6mg of nitrite. Adding the amount from the cooked foods, the total should not exceed 20mg. This amount is not enough to cause nitrite poisoning in most people, as the toxic dose for nitrite is usually above 200mg.
However, not causing acute poisoning does not mean it will not have adverse effects on the body. Hot pot soup contains relatively high levels of amino acids and amines, which can readily react with nitrites under heating conditions to form nitrosamine carcinogens. The carcinogenic dose of nitrosamines for rats is 0.75 mg per day of intake. In dried seafood products, the nationally permitted amount of nitrosamines is only a few micrograms, so what about in the soup? Obviously, the content should be even lower to be reassuring. Although there is no measured data for nitrosamine content in the soup, it is estimated that its value is not low. If one frequently eats hot pot, the risk of promoting cancer should not be underestimated.
In conclusion, here are a few pieces of advice for hot pot lovers:
1. Different types of broths show significant variations in nitrite content after cooking. Broths made with nitrite-rich ingredients like sour cabbage and seafood have particularly high nitrite levels. In comparison, clear soups, bone broths, and yinyang broths are relatively safer.
2. The risk also varies depending on the foods cooked. After cooking high-nitrite foods like sour cabbage and seafood, one should be more cautious when drinking the soup.
3. If you want to drink the soup, it is best not to drink it at the end of the hot pot session. The safest time to drink is within half an hour after starting to cook.
4. When eating hot pot, pair it with plenty of fresh vegetables to reduce the risk of nitrites forming nitrosamine carcinogens. Excessive protein can enhance the effect of carcinogens. Vegetables should not be boiled for too long; it is best to add them early into the soup, rather than waiting until the nitrite content is already very high.
5. After a meal of hot pot meat, the next meal should be lighter. Eat more whole grains, legumes, and vegetables to supplement your intake of dietary fiber, Vitamin C, and antioxidant health-promoting components that help prevent cancer.