Potatoes: The skin of potatoes contains "solanine," which can cause poisoning if it accumulates in the body to a certain level. Because the poisoning caused by it is chronic and its symptoms are not obvious, it is often overlooked.
Persimmons: When persimmons are unripe, tannic acid is mainly found in the flesh, but after ripening, it concentrates in the skin.
Once tannic acid enters the human body, it reacts with proteins in food under the action of stomach acid to form a precipitate—bezoars—which can cause various diseases.
Sweet Potatoes: Sweet potato skins contain a high amount of alkali, and consuming too much can cause gastrointestinal discomfort. The skins of sweet potatoes with brown and black-brown spots are infected with "black spot bacteria," which can produce "ipomeamarone" and "ipomeamarol." These substances can damage the liver and cause poisoning when they enter the body. In mild cases of poisoning, symptoms include nausea, vomiting, and diarrhea. In severe cases, it can lead to high fever, headache, shortness of breath, convulsions, vomiting blood, coma, and even death.
Ginkgo: The skin of the ginkgo fruit contains toxic substances such as "ginkgolic acid," "ginkgolic acid," "ginkgolic acid," and "ginkgol." These substances can damage the central nervous system and cause poisoning after entering the human body. Additionally, the cooked flesh of the ginkgo should not be consumed in large quantities.
Water Chestnuts: Water chestnuts often grow in paddy fields, and their skins can accumulate harmful and toxic biological waste products and chemicals. Additionally, water chestnut skins may contain parasites. Eating unwashed water chestnut skins can lead to diseases.