My Vitiamin D was so low that my doc put me 50,000 units of Vitamin Dba day for 6 weeks until my vitamin D levels were up, then doc put me on 1,000 units a day.

Please get advice from your doctor before you take a large dose of Vitamin D because too much of Vitamin D which could be harmful. Please consult your doctor.😉

I take 4000 a day. I think I feel ok. Not sure if theres a super big difference though.

I take 10k - 15k a day - calibrated against my blood numbers (which keeps me in the desirable range according to the neuro). I think you need to figure out what your blood numbers are and then take an amount that gets your blood numbers in a good range. Hard to say it is helping. I certainly haven't had a relapse or anything, so that's good.

4 vitamin D3 1000iu

I take 5000IU through the summer and 10000IU in the winter
Does it work who knows