Healthy Origins Vitamin D3 1,000 IU is a key nutrient manufactured in a highly absorbable liquid softgel form. Vitamin D3 is synthesized in the body from sunlight and only a small amount can be obtained from food. The winter season and many 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.