There is no research to confirm what type A blood is most afraid of, but type A blood in stomach cancer, cardiovascular and cerebrovascular diseases accounted for a large number of people. 1. Data show that patients with gastric cancer, type A blood accounted for a significant majority, and the lesions occur more in the stomach, therefore, people with type A blood if more dyspepsia, epigastric pain, loss of appetite, atrophic gastritis and other diseases, the need for early medical treatment, to reduce the risk of developing into gastric cancer. In addition, other cancers such as esophageal cancer also account for a larger proportion of people with type A blood. 2. People with blood type A have relatively high blood viscosity, thus increasing the likelihood of cardiovascular diseases and are prone to atherosclerosis and cerebral infarction. However, at present, there is no clear research showing a correlation between blood type and the occurrence of diseases.