Vitamin D is a steroid vitamin, a group of fat-soluble pro-hormones that are best known for the role they play in supporting bone health and aiding in the absorption of calcium and phosphate from the gastrointestinal tract. A growing body of research highlights its important role in supporting other body systems, including cardiovascular and blood sugar balance, musculoskeletal strength, and neurological and immune function, enabled by its ability to target over 200 different genes throughout the body. At the same time, deficiency and insufficiency of this important nutrient have reached epidemic proportions around the world, making the achievement of optimal levels extremely important than ever to overall health and well-being.