Vitamin D also supports healthy bones, muscles & teeth. Microcrystalline Cellulose, Vitamin D3 (Cholecalciferol), Magnesium Stearate. There is no need to go anywhere else for your nutrition needs! Although smaller, Nutrition Geeks' Vitamin D3 provides 4000iu (2000% NRV) per tablet, providing maximum support when Vitamin D 1000iu tablets aren't enough.