Doctors often prescribe vitamin B3, also known as niacin, to treat high cholesterol, according to WebMD. It is also approved for treatment of pellagra, and it shows promise in reducing hardening of the arteries and lowering the risk for a second heart attack.
Evidence also points to vitamin B3 as potentially helpful in reducing the risk of type 1 diabetes in children. It may also be useful in treating osteoarthritis, rosacea and skin cancer, as the University of Maryland Medical Center notes. In addition, people with high levels of vitamin B3 in their diets show a reduced risk of Alzheimer's disease and cataracts.