Recently, a couple in their 50s from Zhejiang, China, cooked some sponge gourds at home. After taking a few bites, they noticed the gourds tasted bitter, but they did not pay much attention because they believed that “bitter gourds can help cool the body.”

As a result, shortly after eating, both of them experienced nausea, vomiting, stomach pain, and diarrhea, and had to be taken to the emergency room. They received emergency IV fluids, stomach protection treatment, and electrolyte balance correction.

Doctors later determined that they had eaten bitter sponge gourd. In fact, cases of poisoning from bitter gourds, pumpkins, and squashes occur almost every summer. Through long-term breeding, these vegetables normally no longer produce bitter compounds and are not supposed to taste bitter (except for bitter melon).

However, a small number of gourds and squashes may become bitter due to factors such as genetics, temperature, sunlight, and soil conditions.

Dr. Han Zhi, Deputy Director of the Emergency Department at Zhejiang Provincial People’s Hospital No. 2, explained that the bitter substance found in bitter gourds and squashes is cucurbitacin, a toxic compound. This toxin is very stable and cannot be destroyed through cooking. Stir-frying, stewing, or boiling at 100°C will not eliminate it, and it can still cause poisoning even after being cooked.

Symptoms of poisoning usually appear around 30 minutes after consumption. Mild cases may include nausea, vomiting, abdominal pain, and diarrhea, while severe cases can lead to liver and kidney damage, seizures, breathing difficulties, and upper gastrointestinal bleeding.

Moreover, bitter gourds and squashes are very difficult to distinguish from normal ones by appearance alone. Therefore, before eating, it is recommended to taste a small piece with the tip of your tongue to check for bitterness. If it tastes bitter, throw it away immediately.

5 Foods That Are Still Dangerous If They Taste Bitter Even After Cooking

1. Sponge Gourd

Normal sponge gourds are harmless, but if they taste bitter, they may contain highly toxic cucurbitacin alkaloids. These compounds are difficult to destroy or dissolve even at high temperatures. Eating them can cause poisoning symptoms.

Symptoms may include dry mouth, dizziness, nausea, fatigue, and drowsiness. Severe cases may lead to vomiting, abdominal pain, diarrhea, dehydration, bloody stools, and even death.

2. Potatoes

Potatoes contain solanine, a toxic substance. Normal potatoes contain low levels of solanine and are safe to eat. However, sprouted or green potatoes have rapidly increased solanine levels. They often taste numb and bitter, and consuming large amounts may cause nausea, vomiting, diarrhea, and even breathing difficulties.

3. Bitter Ginkgo Nuts

Ginkgo nuts contain toxic substances such as ginkgolic acid and hydrogenated ginkgolic acid. Eating them may cause food poisoning, mainly affecting the digestive system. These toxins can be destroyed at high temperatures, so raw ginkgo nuts should never be eaten.

4. Bitter Nuts

Improper storage or storing nuts for too long can cause unsaturated fatty acids in the nuts to become rancid, leading to a bitter or stale taste. Moldy nuts in particular can easily produce aflatoxin.

Aflatoxin is a Group 1 carcinogen, 68 times more toxic than arsenic, and heat-resistant, making it difficult to destroy at temperatures below 280°C.

5. Bitter Almonds

Bitter almonds can cause poisoning more quickly. The hydroglycosides in bitter almonds break down in the body to produce hydrocyanic acid, and eating 20 to 60 almonds may cause poisoning.

Foods With These Abnormal Signs Should Also Not Be Eaten

1. Partially Rotten Fruits and Vegetables

Some people think cutting away the rotten part is enough. However, even after removing the spoiled section, bacteria and mold may already have spread into the healthy-looking parts and produced harmful toxins.

For example, rotten ginger produces safrole, an extremely toxic substance. Even small amounts may cause poisoning and liver cell degeneration, damaging liver function.

2. Red-Core Sugarcane

The red center inside sugarcane is not a sign of high sugar content, but rather mold growth. It may contain the neurotoxin 3-nitropropionic acid, which can cause nausea, vomiting, dizziness, blurred vision, and in severe cases, respiratory failure.

If you notice anything unusual, discard the sugarcane immediately and do not eat any part of it.

3. Dead Crabs

When crabs die, bacteria multiply rapidly inside their bodies, breaking down proteins and producing large amounts of histamine and other biogenic amines.

Histamine is highly toxic and cannot be completely removed even after cooking. It may cause allergic poisoning symptoms such as rashes, itching, and difficulty breathing. Severe cases may lead to anaphylactic shock and become life-threatening.

4. Wood Ear Mushrooms Soaked for Too Long

If wood ear mushrooms are soaked for too long, they may produce a substance called bongkrekic acid, which contains harmful toxins that can cause poisoning if consumed.

Bongkrekic acid is heat-resistant and cannot be eliminated even by high-temperature cooking. Mild poisoning symptoms may include dizziness, nausea, vomiting, and diarrhea, while severe cases may result in internal bleeding, organ failure, and even death.

5. Sweet Potatoes With Black Spots

These black spots are signs of black rot disease in sweet potatoes. The fungi responsible are difficult to destroy at high temperatures and produce toxins called ipomeamarone and ipomeamarol.

These toxins mainly damage the liver, causing symptoms such as vomiting, diarrhea, and fever. Severe cases may lead to hemorrhage and shock.