Some fruit and vegetable peels are rich in nutrients, such as tomatoes, pears, and apples, so many people eat them without peeling. However, there are four types of peels that are best not to eat.
1. Potato skin
Potatoes contain glycoalkaloids, a toxic substance that is almost entirely concentrated in the potato skin, especially in the green and sprouted parts. Some people like to use potatoes with their skins on when stewing beef, but the cooked potato skins still contain glycoalkaloids. Consuming large amounts can cause symptoms such as vomiting, dizziness, and diarrhea.
2. Persimmon skin
The skin of ripe persimmons contains a large amount of tannic acid, which makes them taste astringent. In the presence of stomach acid, tannic acid reacts with proteins in food to form a precipitate known as a persimmon stone. This substance can easily cause symptoms such as upper abdominal discomfort, bloating, and loss of appetite. Therefore, do not eat unpeeled persimmons, and do not eat them on an empty stomach.
3. Sweet potato skin
Sweet potatoes grow underground for a long time, and their skin is in direct contact with the soil, where many harmful substances are absorbed. Moreover, sweet potato skins contain a high amount of alkali, and eating too much can cause gastrointestinal discomfort. Additionally, many vendors selling roasted sweet potatoes on the street save costs by using coke as fuel, and harmful substances like sulfur dioxide can easily accumulate on the sweet potato skin. Therefore, eating roasted sweet potatoes with the skin on carries a risk of cancer.
4. Water chestnut skin
Water chestnuts grow in paddy fields, and their skins absorb many harmful and toxic biological wastes, and also contain parasites. Eating raw water chestnut skins can cause symptoms such as diarrhea and vomiting. Furthermore, it should be noted that water chestnut skins contain a high amount of starch, so diabetic patients should consume them with caution.