e has never been a toxic level
of vitamin D from prolonged sun exposure reported, and total-body summer
sun exposure will make about 10,000 IU of natural vitamin D3 in just 20-30
minutes, so the 2000 IU upper limit appears to be too low to achieve
optimal health. Optimal blood levels to prevent bone fractures in senior
Americans, provide adequate vitamin D during pregnancy and lactation, far
exceed the current upper safe limit.