Vitamin B12 has the following effects: 1. Nourishing nerves, vitamin B12 has the function of nourishing nerves and promoting nerve fiber repair. It is widely used in various neurological diseases, including cerebral hemorrhage, cerebral infarction, transient ischemic attack, facial nerve palsy, spinal cord lesions, demyelinating lesions, peripheral neuropathy, Alzheimer’s disease, Parkinson’s disease, autonomic dysfunction, etc. 2, correction of anemia, vitamin B12 is often used in combination with folic acid to treat megaloblastic anemia, and is mostly used to treat patients with anemia after most of the gastric resection. 3, Promote sleep, vitamin B12 also has the effect of inducing sleep, improving sleep quality and reducing symptoms of excessive dreaming.4. Vitamin B12 also has the effect of relieving sore and dry eyes.