This calcium with vitamin D supplement compares to the active ingredients in Caltrate 600 + D and is formulated to allow calcium to easily be absorbed into the body making it the perfect supplement for adults who want to ensure they are getting the recommended daily intake of these essential nutrients. Vitamin D supplements can be taken with or without food and the full amount can be taken at one time. As your body needs vitamin D to absorb calcium, this formulation is an ideal solution to allow the body to absorb the calcium dosage. The recommended serving size is one tablet, up to two times daily with meals.