Drinking utensils refer to tea cups, tea pots, tea bowls, etc. for drinking tea. Commonly used are porcelain cups, glass cups, enamel cups and thermos cups. Of course, the drinking utensils are good for porcelain, and the enamel cups and vacuum cups are not suitable. Because of the poor permeability of enamel materials, it affects the taste of tea. Some people love to use enamel cylinders to make tea, which is considered to be convenient and can be heated at any time to further torment the tea. In fact, after the tea is tormented, the citric acid in the tea is fried too much. After absorption in the digestive tract, it often combines with the protein in the food to form citrate protein and solidifies, affecting appetite and digestion, and prone to constipation, which is harmful to human health.