Comment by IAmNotBatman_

Yeah we wear too much sunscreen, a significant number of people are vitamin D deficient. From the UltraMind Solution book, you need the active form cholecalciferol in your supplements. You can safely take 5000-10000 IU a day for 3 months to get up to the optimal levels, then 2000 IU a day for maintenance. The Ideal range is 50 to 80 ng/ml in your blood tests. Also just minimal outdoor sun exposure is the best way to get it, no sunscreen. 15 minutes if you're light skinned, 35 if you're really dark.