GNC Niacin 500 240 Tablets by GNC. $37.50. Each tablet supplies 500 mg of Niacin. Niacin offers many benefits: Functions as a coenzyme in glucose oxidation.Provides dietary support for a healthy blood lipid profile.*Plays an important function in energy metabolism.* Kosher and Vegetarian. Small, convenient tablets. * These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.