Vitamin D3 plays a vital role in your immunity, heart health, calcium absorption, and bone strength. Vitamin D3 is the same bioavailable form of D made in our skin through sun exposure and it's nearly impossible to get enough vitamin D from sun and food. Few foods contain vitamin D3. You'd have to eat multiple servings of fatty fish to reach 2,000 IU. The NEW Vita-D3 just became twice as nice with double the potency—2,000 IU of vitamin D3 per tablet.