Esperanza Vitamin D3 5,000 IU is a key nutrient manufactured in a highly absorbable capsule form. Vitamin D3 is synthesized in the body from sunlight and only a small amount can be obtained from food. The further North you live, the less D3 is naturally taken into the body due to reduced levels of available natural sunlight. Regardless of wher you may live, the winter season and most all sunblock products inhibit the body's ability to produce optimal levels of vitamin D. As a result, Vitamin D3 supplementation becomes even more necessary to ensure your body receives an adequate supply.