When it comes to food safety, most people know to steer clear of spoiled leftovers or suspiciously old ingredients. But what if some of the most dangerous foods are lurking in plain sight—on your dinner table or in your fridge—despite being cooked or stored with care? Recent reports from China, highlighted by Nhat Bao Quang Tay and other major outlets, have sounded the alarm about a handful of foods that can pose serious, sometimes fatal, risks even when prepared according to conventional wisdom.
On October 11, 2025, Nhat Bao Quang Tay published a chilling exposé: four types of foods, all seemingly innocuous, are inherently toxic and could cause death if handled or stored incorrectly—even if they’ve been thoroughly cooked. This revelation has caused a stir among health-conscious consumers and families across Asia, and it’s worth taking a closer look at the details. The foods in question? Black fungus (when soaked too long), frog soaked in alcohol, pufferfish, and the blue-ringed octopus. Meanwhile, a separate investigation into overnight foods has revealed additional hazards with common favorites like cooked seafood, soft-boiled eggs, salads with black fungus, and soy milk.
Let’s start with black fungus—often used in Asian cuisine for its crunchy texture and supposed health benefits. The danger comes not from the fungus itself, but from improper soaking. According to the report, soaking black fungus (also known as wood ear mushrooms) for too long can lead to the growth of fumonisin—a toxin more potent than arsenic. This chemical targets the liver, kidneys, and heart, with a death rate of over 60% if ingested. The warning isn’t just theoretical: last year, a family in Quang Tay, China, soaked black fungus for two days before frying and eating it. All members landed in the intensive care unit, and doctors were forced to admit, “There is no antidote for this toxin.” The advice is clear: never soak black fungus for more than 24 hours, and if it smells odd or feels slimy, throw it away without hesitation.
Folk remedies can sometimes do more harm than good, as evidenced by the tragic case of frog soaked in alcohol. Some believe that soaking frogs in liquor creates a potent cure-all, but this misconception has deadly consequences. The entire body of a frog contains toxins that remain lethal even after being cooked at 120°C for four hours. Alcohol only accelerates the release of these toxins, and a single sip can trigger cardiac arrest. In 2024, a man in Quang Dong, China, died after consuming frog-infused alcohol, despite receiving emergency medical care. The lesson, as Nhat Bao Quang Tay puts it, is sobering: “Don’t touch wild frogs and never soak them in alcohol. If you’re sick, see a doctor—don’t gamble with folk remedies.”
Pufferfish might look exotic and tempting on a restaurant menu, but its reputation for risk is well-earned. The fish contains tetrodotoxin, a heat-resistant poison 1,200 times more toxic than cyanide. Cooking, boiling, or frying does nothing to neutralize the danger. In 2023, a man in Phuc Kien, China, stole a wild pufferfish and suffered a fatal bite; he died four hours later. The warning is stark: never attempt to handle or prepare pufferfish at home. Only licensed and highly trained chefs should ever serve this delicacy.
Even the ocean’s more obscure creatures can be deadly. The blue-ringed octopus, with its striking azure spots, carries venom nearly identical to pufferfish toxin. The venom is unaffected by heat or salt, and a single bite can cause respiratory paralysis in as little as ten minutes. Last year, a tourist in Hai Nam, China, mistook a blue-ringed octopus for harmless seafood. Luckily, a sharp-eyed chef intervened just in time, reportedly saying, “One more step and the whole family would have died.” The best defense? If you see a small octopus with vibrant blue rings—especially when agitated—keep your distance and alert others.
But the list of risky foods doesn’t end with these exotic or unusual ingredients. According to a recent feature on overnight foods, many people worry that keeping food in the fridge overnight might lead to high nitrite levels or even cancer. While most foods are safe if stored properly, there are notable exceptions—foods that should never be left overnight, not even once.
First up: cooked seafood. Shrimp, crab, scallops, and oysters are all protein-rich, but their aquatic origins mean they harbor more microorganisms than land-based meats. Even after thorough cooking, bacteria like Vibrio parahaemolyticus can multiply rapidly in the fridge—by as much as 50% after 12 hours. These bacteria produce heat-resistant toxins, so reheating won’t protect you. Symptoms of poisoning include vomiting, diarrhea, fever, and severe dehydration. Plus, the taste and texture of seafood degrade quickly: crab roe freezes, shrimp meat turns rubbery, and the original flavor is lost. The best practice? Cook only what you’ll eat that day, and if you must store leftovers, freeze them immediately rather than relying on the refrigerator alone.
Eggs are another staple with hidden dangers. Soft-boiled or half-cooked eggs with runny yolks are especially risky. The culprit is Salmonella, a bacterium that can survive on the shell and penetrate the egg through microscopic pores. If eggs aren’t fully cooked, Salmonella may persist and even multiply in the fridge. Worse, the toxins produced are heat-resistant, so reheating won’t guarantee safety. Eating contaminated eggs can lead to acute gastroenteritis, vomiting, diarrhea, and fever. Vulnerable populations—elderly, children, pregnant women, and immunocompromised individuals—are at heightened risk for severe illness. The takeaway: eat soft-boiled eggs the day they’re cooked, and never store them overnight.
Salads and cold dishes with black fungus are also problematic. These dishes often skip thorough cooking, leaving bacteria or parasites on the ingredients. Even when refrigerated, harmful microbes can continue to grow. Black fungus, especially when soaked, is a particular concern for bacterial contamination and toxin production. The advice is simple: avoid storing and eating these salads overnight.
Soy milk, a breakfast favorite, is another food to handle with care. Its high protein and water content make it a perfect breeding ground for bacteria. If soy milk is not boiled thoroughly, it can retain digestive inhibitors and saponins, leading to nausea or vomiting. Even if refrigerated, uncovered or improperly stored soy milk can quickly sour and develop harmful bacteria—sometimes without any obvious change in taste or smell. Drinking spoiled soy milk can upset your digestive system and cause diarrhea.
Ultimately, these warnings all boil down to a simple truth: not every food is made safe by high heat or cold storage. As the reports emphasize, “Don’t trust high heat sterilization or folk remedies for these dangerous foods.” Whether it’s an exotic seafood, a home remedy, or a common breakfast item, understanding the risks—and following expert advice—can make the difference between a healthy meal and a life-threatening mistake. In the kitchen, a little caution goes a long way.
