We recommend that people maintain a “healthy” level of 50ng/ml. For an average weight person of 150lbs it usually takes 5000iu a day to do this. Now your starting level is not extremely low, so you can probably take 4000iu a day to get to the 50ng/ml. The 2000iu a day will most likely not get you to the healthy level. There are many studies that show at levels below 40ng/ml, your chances for cancer and autoimmune disease rises dramatically!