Our vitamin D level is intimately linked to our immunity and bone density.  Low levels of vitamin D increase our risk for various cancers. It is important to note that both extremely low (deficiency) and extremely high (toxicity) levels of vitamin D are harmful.  Make sure to ask your doctor to test your vitamin D level before taking this product. The general reference range for vitamin D is between 30 and 100. Your target lab value should be between 70 and 80 ng/ml.  If you are below 45, take 1 capsule per day, with food.
 
References:
Vitamin D and The Immune System
 
Vitamin D Deficiency Induces Early Signs of Aging in Human Bone, Increasing the Risk of Fracture
 
The Role of Vitamin D in Cancer Prevention
 
Vitamin D and Breast Cancer: Latest Evidence and Future Steps
 
Low Vitamin D Status is Associated with Inflammation in Patients with Prostate Cancer