It depends on your sun exposure and kidney health. In the elderly with a compromised kidney, 4000 can push them over a sane limit. For most people though with m

It depends on your sun exposure and kidney health. In the elderly with a compromised kidney, 4000 can push them over a sane limit. For most people though with minimal sun exposure, 4000-5000 is pretty good, and certainly will make them less sick. For optimal effect, stack with calcium and magnesium as citrate or better.