Lactose intolerance is a digestive problem with a high incidence worldwide. The disease occurs mainly due to a lack or deficiency of lactase in the body, which prevents effective digestion of lactose. Congenital lactose intolerance is caused by a genetic defect that prevents the body from producing enough lactase, and its incidence is relatively low. Secondary lactose intolerance is caused by other gastrointestinal disorders, such as celiac disease, and is relatively common. Functional lactose intolerance is the most common form of lactose intolerance, in which lactase activity is reduced or lactose absorption is impaired, but there is no apparent organic disease. This article lists several possible solutions for different types of lactose intolerance based on the latest research. In studies of lactose intolerance, scientists have found that the rate of lactose intolerance varies widely across populations, with significant differences in prevalence by race and region. In addition, several studies have shown a link between lactose intolerance and the composition of the gut microbiome. Therefore, the study of lactose intolerance has important implications for understanding how the human digestive system works and the relationship between the gut microbiome and health.