We often say: the nutritional value of fruits and vegetables is all in their skin. Fruit and vegetable peels are rich in nutrients and active ingredients, so to absorb them all, you should eat them with the skin. While this method seems to provide the "full nutrition" of the food, some "unwelcome elements" might also be mixed in and consumed along with it.
Potato stew with beef, Di San Xian (a classic dish of stir-fried potatoes, green peppers, and eggplant) are common dishes on the dining table of many families. Many people boil potatoes with the skin on, thinking that high temperatures solve all the problems. This is not the case. Potatoes contain a substance called "solanine" to resist pests and diseases. The content of solanine is higher in the potato peel. It can cause poisoning when it accumulates to a certain level in the body. Potatoes with green skin or sprouts contain even higher levels of solanine, and excessive consumption can cause a series of gastrointestinal reactions such as nausea and vomiting. Therefore, potatoes must be peeled before cooking.
Sweet potatoes are nutritious but are alkaline foods, and eating too many can cause "heartburn." The skin of sweet potatoes contains even more alkaline substances. If you often eat sweet potatoes with the skin, it can cause gastrointestinal discomfort. Moreover, brown to blackish-brown spots on the sweet potato peel may be an infection with "black spot disease," which can cause poisoning after consumption.
Water chestnuts are sweet, crispy, and refreshing, a favorite of many people. However, the skin of water chestnuts may contain parasites such as fasciolopsiasis. Eating the unwashed skin of water chestnuts can also lead to illness.
Although ginkgo has many benefits, it is slightly toxic and should not be eaten in excess. The skin, in particular, contains toxic substances such as "ginkgolic acid," and excessive consumption can damage the central nervous system and cause poisoning. When eating them, you must not only remove the inner skin but also avoid excessive consumption of the cooked ginkgo nut.
In addition, due to the large use of chemical fertilizers nowadays, nitrate contamination of fruits and vegetables is severe. Therefore, it is recommended to peel fruits and vegetables whenever possible. Especially for fruits like apples, pears, and grapes, which are cultivated for longer periods and have better taste, their skins often harbor many microorganisms, pesticides, and other residues. Therefore, it is not worth risking your health for a little bit of nutrition.