In the season when it's neither too cold nor too warm, many people choose to carry a thermos cup to enjoy warm drinks anytime. However, while thermos cups are convenient, they are not suitable for all beverages. The following four drinks should not be stored in them, as doing so offers no benefits.

1. Milk

Milk is rich in nutrients, and many people carry it for convenience. However, because of its nutritional richness, vitamins and other nutrients can be easily destroyed at high temperatures. Additionally, microorganisms in milk can rapidly multiply in warm conditions, leading to spoilage and potentially causing diarrhea or stomach pain.

2. Acidic Juices

Juices should not be kept at high temperatures to avoid the destruction of vitamins. Moreover, highly acidic juices can react chemically with the inner lining of the thermos cup, posing health risks.

3. Tea

Tea contains tannic acid, tea alkaloids, aromatic oils, and various vitamins, which are best extracted with water at around 80°C. If tea is brewed in a thermos cup, the leaves may ferment under prolonged high temperatures, destroying vitamins, evaporating aromatic oils, and leaching excessive tannic acid and tea alkaloids. This not only reduces the tea's nutritional value but also makes it tasteless, bitter, and potentially harmful.

4. Traditional Chinese Medicine

Acidic compounds in traditional Chinese medicine can react with the chemical materials in the thermos cup, producing harmful substances. It is recommended to store such medicine in ceramic or enamel containers instead.