my son has been taking 2000iu of D3 for several months and we recently increased him, first to 10,000, then to 50,000, hoping to improve his osteoporosis. we went to an amusement park yesterday with our youth group and he was one of the only people who didn't get burnt. my son is extremely pale and i was sure he'd end up burning. i was going to have him use sunscreen after some time in the sun but it ended up never being necessary. we were in the florida sunshine from 9am til 6pm. of course he wasn't in the sun that whole time but most of it!