Anything under 10,000 IU is safe. for most people BUT its complicated because without adequate vitamin A and K the limit can be different, whether higher or lower than that. Also vitamin D will deplete magnesium if intake is not meeting the bodys needs because vitamin D and magnesium need to be working together for each to work properly. Also without calcium intake vitamin d can be a little dangerous as some research shows that high Vitamin D without enough calcium causes the body to absorb more heavy metals in its place. Also absorbtion and utilization of vitamin D3 is genetic and some people can hit optimal blood levels on 2000 iu, other need 20,000! But for the average MAN 5000-7000 IU A day would be best with sufficient vitamin A and K Along with some calcium.
