Non GMO Bioavailable D3 Active Form Dietary Supplement Purity Guaranteed - Meets Strict Government Safety Standards for Heavy Metals & Toxins Research suggests that Vitamin D may be your single most important supplemental nutrient. Required for calcium absorption, vitamin D helps maintain healthy bones and teeth. It also supports a healthy immune system, as well as the health of the heart, pancreas, breast, colon and prostate tissues. Vitamin D is typically obtained from the diet or produced by the skin from sun exposure. However, vitamin D is not abundant in food and people increasingly avoid the sun. Therefore, supplementation is necessary to ensure healthy levels of this key nutrient.