I am a 30 y/o male weighing app. 72 kg. I had a concentration of 20 ng/mol on the 20190403 and started taking two pills of VitaShine D3 2500 IU a day (i.e. a daily dose of 5000 IU) on the 20190403. 164 pills later (i.e. 410000 IU later), on the 20190703, the concentration was 51.2 ng/mol. In other words, 3 bottles of VitaShine D3 25000 IU proved enough to reach optimal levels. Thank you Vegetology!