According to research by medical experts in the United States and the United Kingdom, milk contains two substances that induce sleep. One is tryptophan, which is used by the body to synthesize serotonin and promotes sleep. The other is a natural morphine-like substance with anesthetic and sedative effects. Therefore, drinking milk in the morning will inevitably inhibit the cerebral cortex of the brain, affecting daytime work and study.
In addition, drinking milk in the morning is also not conducive to digestion and absorption. This is because the protein in milk must be broken down by the stomach and small intestine into amino acids before it can be absorbed by the body. In the morning, when the stomach is empty, the emptying of the stomach and intestines is very fast. Consequently, the milk is excreted into the large intestine before it can be digested. Furthermore, absorbed protein from food can only be used to build body tissues on the basis of sufficient caloric intake. If calorie intake is insufficient, the absorbed protein is quickly converted into energy and consumed, which is undoubtedly a waste.