I take 4000 IUs a day on the 45th parallel from late September to April, 2000 IUs during the summer. More than one doctor has OKed this dose. I was at 8-10 ng/

I take 4000 IUs a day on the 45th parallel from late September to April, 2000 IUs during the summer. More than one doctor has OKed this dose. I was at 8-10 ng/ml a few years ago and now I take Vitamin D very seriously.