The cold winter weather has made clay pots increasingly popular. Ms. Li is a typical example; she now feels that other containers contain too many chemicals, whereas clay pots offer a return to simplicity, giving a sense of safety and health. The steaming hot food is very appetizing, so now a clay pot dish is indispensable for every meal at her home.
Wang Yi, Director of the Diet and Nutrition Department at Guang'anmen Hospital, China Academy of Chinese Medical Sciences, explains that clay pot dishes should not be eaten frequently. This is because the common clay pots we use are mainly made of clay, with added feldspar and quartz, fired at high temperatures. Although cooking food in them imparts a unique flavor, if heated for too long, the protein in animal-based ingredients degrades, the water's dissolving ability weakens, and a large amount of gelatinous liquid is excreted, increasing its toughness and resulting in a poor texture when eaten, which is not conducive to human digestion and absorption.
Furthermore, when stewing food in a clay pot, due to the tight seal, odor-causing substances from the ingredients are difficult to escape. Some valeric acid, valeraldehyde, and low fatty acids remain in the food and broth, generating harmful substances to the human body during thermal reactions. Most clay pots are glazed and sintered, and harmful substances like lead and arsenic can be released through repeated heating. Inorganic salts such as feldspar and quartz can also leach out. If consumed over a long period, they can cause chronic poisoning in the body.
When stewing food in a clay pot, the average nutrient loss rate is relatively high, especially for inorganic salts like calcium, phosphorus, iron, zinc, and iodine in animal and plant ingredients. The average loss rate for vitamins B1 and B2 is as high as about 89%, and the loss rate for vitamin C can even reach 100%. Therefore, when eating clay pot dishes, it is necessary to additionally consume raw vegetables and coarse grains to compensate for the loss and deficiency of nutrients.