Low salivary acid may mean that the body’s defenses are reduced and it is vulnerable to bacterial attack. It is generally a physiological phenomenon and can be caused by factors such as living conditions or medications. Salivary acid in the human body is often in the form of oligosaccharides, glycolipids or glycoproteins, a negatively charged ion that can produce a smooth feeling of saliva, which has the effect of preventing the invasion of germs. Salivary acid is not only a transmitter of gangliosides, but also a constituent of the brain. In medicine, changes in the concentration of serum salivary acid can be used as an auxiliary indicator of malignant tumors and efficacy diagnosis. The significantly higher concentration of salivary acid is mostly seen in diseases such as leukemia, head and neck tumors, liver cancer and other malignant tumors. Therefore, there is no need to pay special attention when salivary acid is low, but drink plenty of water and review regularly.