Whether the procedure is an orthopedic repair, an abdominal operation, or a cosmetic intervention, the body has to move through the same overlapping phases: hemostasis , inflammation , proliferation , and remodeling
Studies treating mild to moderate B12 deficiency in older people have failed to provide cognitive benefits: A clinical trial from the Netherlands measured the cognitive response to B12 supplements in people 70 years old with mild B12 deficiency and MMA levels 320 nmol/l (average: ~450 nmol/l)
You can also increase levels of NAD through lifestyle factors like getting regular exercise and restful sleep, as well as eating a healthy diet with foods containing niacin (vitamin B) found in meat, fish, dairy products, and certain vegetables, such as cabbage and cucumbers
For general safety background, refer to CDC Safe Injection Practices
For some men, they notice changes in weeks