Know your blood levels - This brand is a good one for me!
It is great for myself with very low Vit. D , I am staying inside most of the time. They have a 5000IU too. It is excellent for me to drop to5000 during summer 3 months when I do get outside. 1 very important thing though I believe in getting blood tests in Jan/Feb at the coldest part of the year and again in august in the heat to make sure I don't over do it. Like anything too much or too little is not balance out of balance causes many health issues.. if one brand doesn't lift your levels find one that works for you like this does for me.