Vitamin D3 Benefits: Supports healthy teeth and bones by enhancing the absorption of calcium; supports immune function and cardiovascular health* | Optimal Absorption: Vitamin D3 (as cholecalciferol) is more potent and better absorbed than vitamin D2 (or ergocalciferol); research shows vitamin D3 is more effective at raising overall vitamin D levels* | Advanced Vitamin D: Nutrient support for those low in vitamin D, such as those who live in northern latitudes, are elderly, have a darker skin tone, or lack adequate sun exposure to support the body's natural vitamin D production* | Third-Party Certified: This product has been third-party tested and certified to verify what's in the package matches what's on the label and to confirm it contains no unsafe levels of contaminants | Trusted: Thorne is chosen by champions and trusted by 100+ professional sports teams, a proud partner of U.S. National Teams, and the #1 recommended clinical brand by health-care practitioners (2023 Health-Care Practitioner Seller Survey)