Doctor's Best Vitamin D3 1000IU is a nutrient that is critical to many bodily functions, in particular immunity, mood and bone health. Vitamin D3 is beneficial for supporting bone health, immune wellness, cardiovascular function and cellular metabolism - among others. Mounting research is highlighting the ever-increasing benefits of optimal vitamin D3 status. Vitamin D3 is known to interact with over 200 different genes and thus plays a crucial regulatory role as a metabolic activator for a multitude of metabolic processes. Science-based nutrition Dietary supplement The vitamin D3 contained in this product is derived from lanolin, a component of sheep's wool