Finish soaked wood ear and white fungus the same meal and don't keep them overnight, eat wet rice noodles such as flat rice noodles and rice noodle rolls the day you buy them, and don't ferment corn or rice flour at home

Cost

Free. Soak only as much wood ear and white fungus as you will eat, and throw out the rest. Buy only as much wet rice noodle as you can finish that day. The hard part is throwing out what you soaked too much of, and that some families are used to making suantangzi (酸汤子, fermented corn noodles) themselves.

What you get

In China's national surveillance of foodborne disease outbreaks, 19 bongkrekic acid poisonings were reported from 2010 to 2020. 146 people fell ill and 43 died, a case fatality rate of 29.5% (meaning 29.5% of the people who fell ill died). By the food eaten: home-fermented corn products caused 9 incidents and 33 deaths. Wet rice noodles caused 5 incidents and 7 deaths. Wood ear caused 3 incidents, with 5 people ill and 3 dead. In 2020 China reported 143 deaths from food poisoning, of which bongkrekic acid accounted for 12. Ahead of it were poisonous mushrooms (80 deaths) and methanol (14). A notice from the Beijing Municipal Administration for Market Regulation (北京市市场监管局) states that bongkrekic acid is not destroyed by boiling at 100℃ or by pressure cooking, and there is currently no specific antidote. From 2018, Guangdong required wet rice noodles to be sealed in small packages with the shelf life clearly marked. Before and after, the province's yearly cases fell from an average of 6.25 to 0.5

Notes

In October 2020, several families in Jidong County, Jixi City, Heilongjiang ate home-made suantangzi (酸汤子) for breakfast. All 9 people who ate it died. Soaking wood ear in cold water for an hour or two is enough; the advised soaking times differ from place to place, and Hunan says no more than 8 hours at most. If the pieces are slimy, have lost their springiness, smell sour or rotten, or the soaking water is cloudy, throw out the whole bowl. If you vomit, feel dizzy or weak all over after eating, induce vomiting right away and go to the hospital with the leftover food. Anyone who ate with you should be checked even without symptoms. For wild mushrooms, see §1.5 (don't eat wild mushrooms).

Evidence grade

B : Supported by research but without a precise number, or based on small or single studies.

Sources

1. Zhang H et al. (2023). Epidemiology of foodborne bongkrekic acid poisoning outbreaks in China, 2010 to 2020. PLoS One 18(1):e0279957: "From 2010–2020, a total of 19 BA poisoning outbreaks were reported to the China National Foodborne Disease Outbreak Surveillance System. These outbreaks involved 146 illnesses, 139 hospitalizations, and 43 deaths, with a case-fatality rate of 29.5%." https://doi.org/10.1371/journal.pone.0279957
2. Li H et al. (2021). Characteristics of Settings and Etiologic Agents of Foodborne Disease Outbreaks — China, 2020. China CDC Weekly 3(42):889-893. https://doi.org/10.46234/ccdcw2021.219
3. Yuan Y et al. (2020). A Foodborne Bongkrekic Acid Poisoning Incident — Heilongjiang Province, 2020. China CDC Weekly 2(51):975-978: "In October 2020, 9 persons in Jidong County, Heilongjiang Province died after consuming a homemade fermented corn flour product — sour soup — with a case fatality rate of 100%." https://doi.org/10.46234/ccdcw2020.264
4. Liu Z et al. (2026). Controlling the Storage Time Is an Effective Measure to Reduce the Risk of Bongkrekic Acid Poisoning Caused by Wet Rice Noodles. Foodborne Pathog Dis 23(7):468-472 (published online 2025-05-12): "The annual average number of BKA poisoning cases in Guangdong Province dropped from 6.25 before implementing the code to 0.5 after implementing the code." https://doi.org/10.1089/fpd.2024.0131
5. Beijing Municipal Administration for Market Regulation (2023). Risk Alert on Food Poisoning Caused by Bongkrekic Acid [in Chinese]: "Bongkrekic acid is heat-stable and is not destroyed by boiling at 100℃ or pressure cooking" "At present, there is no specific antidote for bongkrekic acid" "White fungus, wood ear and their processed products that were soaked the day before must not be eaten" "Pieces that have lost their shape, are sticky, have no elasticity or smell off must not be eaten" "Induce vomiting as soon as possible to empty the stomach contents and reduce the amount of toxin absorbed; get to a hospital for treatment promptly". https://scjgj.beijing.gov.cn/hdjl/xfts/202309/t20230904_3248296.html
6. Hunan Provincial Administration for Market Regulation (2025). [Food Safety Science] Fatal Warning on Bongkrekic Acid [in Chinese]: "Soak white fungus in cold (room-temperature) water for 3~4 hours and wood ear in cold water for 1~2 hours, changing the water 1~2 times along the way to remove microorganisms; the soaking time must not exceed 8 hours in any case" "If the soaked white fungus or wood ear feels sticky, has poor elasticity or a sour, rotten smell, or the soaking water is cloudy, it has spoiled and should be thrown away immediately" "When poisoning occurs, induce vomiting right away to reduce absorption of the toxin; keep the suspect food if possible and seek medical care promptly" "Everyone who ate the same food, whether or not they have symptoms, should be taken to a hospital for examination". https://amr.hunan.gov.cn/amr/xxx/xtdtx/202506/t20250630_33725786.html
7. Guizhou Provincial Administration for Market Regulation (2023). Food Safety Warning on Guarding Against Bongkrekic Acid Poisoning [in Chinese]: "When buying white fungus, wood ear and similar foods, choose reputable channels, do not soak them overnight, and process and eat them promptly". https://amr.guizhou.gov.cn/zfxxgk/fdzdgknr/tzgg_5626971/tzgg_5626972/202307/t20230728_81318622.html

Translated from the Chinese original. Original book, section 1, tip 48. This section is about health and medicines. It is general information, not a substitute for a doctor’s diagnosis or prescription. Content may be out of date and rules differ by place. When you actually deal with an agency, a doctor or a court, follow what local officials, doctors and lawyers tell you. Disclaimer