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. This toxin can't be seen: in several wet rice noodle poisonings in Guangdong, none of the people who ate it noticed anything wrong with the taste or color of the noodles. 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. Don't buy fresh white fungus. 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 等 (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 等 (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 等 (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 等 (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（2025-05-12 网络首发）：「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. 北京市市场监督管理局 (2023). 关于米酵菌酸引发食物中毒的风险提示：「米酵菌酸对热稳定，经100℃煮沸和高压烹饪也不能被破坏」「目前，尚无米酵菌酸特效解毒药物」「隔天泡制的银耳、木耳及其加工制品不能食用」. https://scjgj.beijing.gov.cn/hdjl/xfts/202309/t20230904_3248296.html
6. 湖南省市场监督管理局 (2025). 【食安科普】米酵菌酸致命警告：「银耳冷水（室温）浸泡34小时，木耳冷水浸泡12小时，中途换水1~2次，去除微生物，泡发时长最长均不能超过8小时」「吃了同样食物的人，不管有没有症状，都应送医院检查」. https://amr.hunan.gov.cn/amr/xxx/xtdtx/202506/t20250630_33725786.html
7. 贵州省市场监督管理局 (2023). 关于谨防米酵菌酸中毒的食品安全警示：「选购银耳、木耳等相关食品时，要选择正规渠道，泡发不可过夜，应及时加工食用」. 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