T2T is absolutely right about D3. I will CHIME IN !
I take 10,000 IU daily for a blood test reading of 73.
Now I want to tell you about the chest colds I got EVERY YEAR prior to taking D3. I mean to tell you they were devastating, and they lasted for WEEKS even MONTHS! Sometimes even leaving me with a squeeky voice! Not only chest colds, but the FLU when it was going around as well. Just imagine a super nasty chest cold and the FLU, too!
Since taking D3 over the past 10 years, nothing. No colds, no flu no nothing. If I feel a sniffle coming on, I go up to 20,000 IU D3 for a week. End of sniffle !