Evidence

Research on the use of oral niacin to treat specific conditions shows:

• High cholesterol. Prescription niacin is used to increase high-density lipoprotein (HDL) cholesterol — the "good" cholesterol that helps remove low-density lipoprotein (LDL), the "bad" cholesterol, from your bloodstream. Despite niacin's ability to raise HDL, research suggests that niacin therapy isn't linked to lower rates of death, heart attack or stroke.
• Niacin deficiency (pellagra). Niacin and a related nutrient called niacinamide are used to treat or prevent niacin deficiency. This condition isn't common in the United States.

Niacin deficiency has been linked to birth defects. A study in mice suggested that niacin supplementation during gestation prevented birth defects. Research is needed to prove a similar benefit in humans.